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No. 128 – June 2007 Czech Republic joins ESO Progress on ALMA CRIRES Science Verification Gender balance among ESO staff The Organisation

The Czech Republic Joins ESO

Catherine Cesarsky The XXVIth IAU General Assembly, held This Agreement was formally confirmed (ESO Director General) in Prague in 2006, clearly provided a by the ESO Council at its meeting on boost for the Czech efforts to join ESO, 6 December and a few days thereafter by not the least in securing the necessary the Czech government, enabling a sign- I am delighted to welcome the Czech public and political support. Thus our ing ceremony in Prague on 22 December Republic as our 13th member state. From Czech colleagues used the opportunity (see photograph below). This was impor- its size, the Czech Republic may not be- to publish a fine and very interesting pop- tant because the Agreement foresaw long to the ‘big’ member states, but the ular book about Czech astronomy and accession by 1 January 2007. With the accession nonetheless marks an impor- ESO, which, together with the General signatures in place, the agreement could tant point in ESO’s history and, I believe, Assembly, created considerable media be submitted to the Czech Parliament in the history of Czech astronomy as well. interest. for ratification within an agreed ‘grace pe- The Czech Republic is the first of the riod’. This formal procedure was con- Central and East European countries to On 20 September 2006, at a meeting at cluded on 30 April 2007, when I was noti- join ESO. The membership underlines ESO Headquarters, the negotiating teams fied of the deposition of the instrument of ESO’s continuing evolution as the prime from ESO and the Czech Republic arrived ratification at the French Ministry of European organisation for astronomy, at an agreement in principle, which was Foreign Affairs. whilst at the same time it enables Czech subsequently presented to the Commit- astronomers to become fully integrated tee of Council. We look forward to an active Czech parti- in the European astronomical community. cipation in ESO’s programmes in time to come. As always in such cases, joining an international organisation requires a process with a political underpinning and a set of formal steps. Not surprisingly, this process can take years. In the case of the Czech Republic the first informal Ms. Miroslava Kopicová, Minister of contacts occurred at the time of the Education, Youth and Sports of the Czech Republic, and Tom Wilson, XXVth General Assembly of the IAU in Associate Director of ESO, shake Sydney, Australia. hands following the signing of the agreement for the entry of the Czech Discussions continued in the Czech Re- Republic into ESO which took place on 22 December 2006 in Prague. public leading to an invitation for me to The formal accession took place, with- visit Prague on 10 November 2005. out ceremony, on 30 April 2007. During the visit, in which I was accompa- nied by Claus Madsen, we had very successful interactions with high-ranking Czech officials, including Prof. Václav Photo: Academy of Sciences of the Czech Republic Pacˇes, President of the Czech Academy of Sciences, and representatives of several ministries. We were also received by Dr. Martin Jahn, the then Deputy Prime Minister of the Czech Republic, who expressed strong support for the Czech bid to join ESO. The visit also included a major press conference and a live TV interview with Dr. Jan Palouš, of the Dr. Jan Palouš of the Astronomical Institute of the Academy of Astronomical Institute of the Czech Academy Sciences, and myself. of Sciences addressing delegates at the ESO It was clear that the process was gaining Industry Day held in considerable momentum, and thus the Prague on 8 June 2007. Photo: L. Calçada, ESO formal request for membership arrived in the spring of 2006, leading to the establishment by the ESO Council of a negotiating team, chaired by Council Vice-Presi- dent Dr. Monnik Desmeth.

The Messenger 128 – June 2007 The Organisation

Astronomy in the Czech Republic

Jan Palouš, Petr Hadrava (Astronomical Institute, Academy of Sciences of the Czech Republic)

A brief historical outline of the development of astronomy in the Czech lands is presented, followed by an overview of the current observational, research and educational facilities.

Historical development

In the Czech lands, astronomy has rather deep roots, covering at least all the last millenium. A significant milestone for pursuing astronomy in Bohemia and surrounding countries was represented Photo: Hadrava, P. Astronomical Institute, Academy of Sciences of the Czech Republic by the establishment of the University in Prague by the Emperor Charles IV in 1348. Astronomy, as one of the seven liberal arts, was greatly emphasised right from the beginning of the lectures, and Prague Figure 1: The Astronomical Clock in the Figure 2: New star of 1572 in the constellation of University soon began to support the Old Town of Prague. Cassiopeia from “Dialexis” by Thaddaeus Hagecius (Frankfurt am Main 1574). creative development of astronomical knowledge brought especially from Paris, planetary motions, while evaluating the physiology of the human eye. Of abso- Oxford and other places in Europe. It positions of Mars observed by Tycho lutely cructial importance for the future reached a remarkable level, e.g. in wide- Brahe. He published numerous treatises, development of astronomy and other ly spread treatises “On the construc- among them “Astronomia nova” includ- sciences was the idea of the influence of tion and on theuse of the astrolabe” by ing the laws of planetary motions, texts a binary star’s motion on the colour of Cristannus de Prachaticz (1407) or in the on the “New Star” of 1604 in the constel- their light, which Christian Doppler, the design of the Prague Astronomical Clock lation Ophiuchus, and he wrote his first professor of the Prague Polytechnic, pre- (1410) by Johannes Schindel. version of “The Dream, or Posthumous sented in his lecture held in the Caroli- Work on Lunar astronomy” on the astron- num in 1842. He published his result in a The most famous era of astronomy in omy viewed from the surface of the Prague was probably the period of rule of Moon. the Emperor Rudolph II at the turn of the 16th and 17th century, when Tycho After the Thirty Years War, education was Brahe and Johannes Kepler dwelt and predominantly provided and controlled worked at the Emperor’s court. The fact by the Jesuit order. Astronomy, as well as that Brahe, and later also Kepler, came other sciences, was pursued mainly in to Prague, as well as Kepler’s success the Clementinum College in Prague. achieved in this city, were not a result of In 1722 the Astronomical Tower was built some lucky coincidence or the Emperor’s there. Thanks to the care of the first direc- Photo: I. Král, National Library, Prague generosity and eccentric nature. To a tor of the Clementinum observatory, great degree, these were logical conse- Josef Stepling, the Astronomical Tower quences of the gradual development was equipped with new instruments of Prague’s cultural and scientific environ- around 1750, becoming the first state- ment. It was mainly Tycho’s friend supported astronomical observatory in Thaddaeus Hagecius, who prepared the Czech lands. grounds for Tycho’s arrival. Hagecius was the Emperor’s physician, and at the The advance of astronomy went hand in same time one of a few European as- hand with the development of other Figure 3: The allegory of sciences on the ceiling tronomers of that time, who, like Tycho sciences. Among the important scientific fresco in the New Mathematical Hall in Prague Brahe, studied the skies with a critical personalities in the 19th century were Clementinum. It shows the Clementinum Astronomi- scientific approach. It was in Prague the mathematician Bernard Bolzano and cal Tower along with the extrasolar planetary systems according to Giordano Bruno’s idea of the where Kepler found, during his stay in the the biologist Jan Evangelista Purkyneˇ, “multiplicity of worlds” (National Library of the Czech years 1600–1612, his first two laws of who studied, besides other things, the Republic).

The Messenger 128 – June 2007 The Organisation Palouš J. and Hadrava P., Astronomy in the Czech Republic

local Bohemian journal, consequently his servatory at Ondrˇejov near Prague. In Current Facilities principle was later rediscovered by H. A. 1928, Josef Jan Fricˇ donated his observ- Fizeau. In the second half of the 19th cen- atory to the state. The Astronomical Institute of the Acad- tury, Ernst Mach contributed enormous- emy of Sciences of the Czech Republic ly to the education of a whole generation After the establishment of the Czechos- has a prominent position as the largest of both German and Czech physicists lovak Academy of Sciences in 1953, the professional place in the Czech Republic. and astronomers. He also helped in the former State Observatory in Clementi- The names of the Institute’s four scien- general recognition of Christian Doppler’s num, together with the Ondrˇejov Observ- tific departments suggest a lot about its achievement. atory, became the basis of the Astro- scientific profile: Solar Physics; Interplan- nomical Institute of the Czechoslovak etary Matter; Stellar Physics; and Galax- In 1886, the Astronomical Institute of the Academy of Sciences. One historical root ies and Planetary Systems. Charles University in Prague was estab- of this institution thus reaches to 1722, lished by August Seydler, who served as when Clementinum observatory was The Solar Physics department focuses its first director. He elaborated sophisti- established by the Jesuits, and another on active solar phenomena such as cated methods for determination of orbits to the Fricˇ’s foundation of the Ondrˇejov sunspots, solar flares and coronal mass of minor planets and wrote textbooks Observatory in 1898, which was inspired ejections. The data coming from the on theoretical physics and many popular by the interest of his poetic godfather instruments of the Ondrˇejov observatory, articles on astrophysics. In the last de- Jan Neruda. including optical and radio wavebands, cade of the 19th century, Seydler’s suc- are combined with X-ray and UV obser- cessor, Gustav Gruss, observed variable vations from satellites and space probes stars and carried out visual observations of stellar spectra.

Albert Einstein spent one and a half years (1911–1912) in Prague, being appointed professor at the German Prague Univer- sity. During his Prague time he published eleven papers, including the first one on the deflection of light by the gravitational field of the Sun, containing the formula- tion of the first fundamentals of the theory of General Relativity.

There is an interesting connection between astronomy and literature: Jan Neruda (1834–1891), Czech poet, writer and journalist, was born in Prague, and grew up in a colourful part of the town called Malá Strana (Lesser Quarter). His first laurels came from the success of his collection of poetry called “Cosmic Songs” that documented his good astronomical knowledge. The song No. XXII “… are there frogs there, too?” was, on the occasion of the 26th General Assembly of the IAU in Prague, translated by Robert Russel into English. Jan Neruda was godfather of Josef and Jan Fricˇ, the sons of the revolutionary Josef Václav Fricˇ, who were born in Parisian exile. Both brothers shared an interest in astronomy with their godfather. When they came back to Bohemia, they started their astronomical observations, at first with the support of professor Vojteˇch Šafarˇík. Later, they established a factory in Prague, which Figure 4: The observation of fireballs has a long produced optical devices, and developed tradition at the Ondrˇejov Observatory. The photograph taken on 12 September 1923 by Josef astronomical instruments. After the death Klepešta shows the M31 galaxy in Andromeda with of younger brother Jan, Josef built an ob- a fireball in front.

The Messenger 128 – June 2007 Figure 5: Ha filtergram (left panel) and corresponding Ha spectrum (right) of a solar active region as obtained by the Ondrˇejov large horizontal solar telescope HSFA2 on 4 July 2006. Note the Doppler shifted features in the spectrum (wavelength increasing to the right).

to have a complex multi-wavelength information on these fast non-equilibrium phenomena. The observations are compared to numerical simulations trying to discover the basic mechanisms ruling the Sun. The main goal is the study of mag- netohydrodynamic and radiative processes in the solar plasma, which offers conditions unachievable in laboratories on Earth. The Sun-Earth relation and cosmic weather are also studied with a lot of geophysical and other practical applications.

The department of Interplanetary Matter operates the European network of all-sky cameras, which records meteors, particularly the brightest of them, which are called fireballs. This network holds the Photo: J. Havelka, Astronomical Institute, Academy of Sciences of the Czech Republic world’s primacy in finding meteorites upon observation of their passage through the Earth’s atmosphere. In 1959, parts of the meteorite Prˇíbram were found upon calculation of its path through the Earth’s atmosphere based on photographs taken by all-sky cameras. The network of all-sky fireball cameras and spectral cam- Figure 6: The 2-m eras has been in continuous operation telescope in Ondrˇejov. since 1963 and is currently the only one in the world. The atmospheric fragmen- rotation and the detection of near-Earth cially binary stars. The photometric and tation and structural properties of me- asteroids. In recent years, new discover- spectral observations are combined to teoroids, chemical composition of me- ies have been made of several binary and disentangle the orbital parameters of bi- teoroids from spectroscopy, physics of very rapidly rotating asteroids. naries. The use of spectroscopy requires meteor radiation and ionisation, and long- the development of the theory of stellar term activity of meteor showers from The Stellar Physics department operates atmospheres, as well as other methods radar observations, are studied. In 1993 a the largest telescope on the territory of of processing and evaluation of observa- new programme of CCD observations the Czech Republic, which has a primary tional data. Interacting binaries are usu- of asteroids using a dedicated 0.65-m mirror of 202 cm diameter. The main ally strong sources of X-ray radiation as telescope started with the focus on their focus is on the study of variable, espe- observed from space probes.

The Messenger 128 – June 2007 The Organisation Palouš J. and Hadrava P., Astronomy in the Czech Republic 20 20 20 20 20 10 10 10 10 10 0 0 0 0 0 X (kpc) X (kpc) X (kpc) X (kpc) X (kpc) –10 –10 –10 –10 –10 1590 1610 1630 1650 1670

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Figure 7: Gas stripping in galaxy clusters: formation grees with respect to the disc normal and observations mainly deal with orbits of a bow shock in front of a galaxy as seen in sim- sees the system from the left side. Su- and light curves of asteroids, including ulations using N-body SPH with a gravity tree code. From Jáhym, P., 2006, Ph.D. Thesis, Charles Uni- perposition of several tens of such spots new discoveries of such bodies. Studies versity Prague, and Université Pierre et Marie Curie, then contributes to the source variability in cosmology, with special emphasis Paris. as the spots arise, trace some part of the on the properties of gamma-ray bursts, orbit, and gradually fade away (c.f. Eckart are performed. Studies in history of as- The department of Galaxies and Plane- et al. 2006). tronomy focus particularly on the Bohe- tary Systems resides in the Prague part mian region. of the Astronomical Institute, but it has its In the Institute of Physics of the Academy own zenith telescope in Ondrˇejov. It deals of Sciences of the Czech Republic, a The Institute of Theoretical Physics of the with the study of the rotation of the Earth, research group participates in the project Charles University is also a part of the and with the theoretical problems of So- of the Pierre Auger Observatory which Faculty of Mathematics and Physics. Stu- lar System dynamics and exoplanets. The is building an array of telescopes in Ar- dents are educated in mathematics and trans-Neptunian bodies are studied in- gentina to detect showers of high-energy computing, and in theoretical physics, cluding the resonance in the Kuiper Belt. cosmic rays. The contribution of the including classical and quantum mechan- Triggered star formation in the turbulent Czech Republic includes mainly the fabri- ics, elementary particle physics, thermo- interstellar medium is studied both in cation of hexagonal mirrors for two the dynamics, relativistic physics and cosmol- observations and simulations. The influ- Schmidt cameras observing Cherenkov ogy. Research areas include gravitational ence of gas recycling on galaxy evolution radiation in the Earth‘s atmosphere. collapse with small non-spherical per- across a Hubble time, including gravi- turbations, black-hole electrodynamics, tational and hydrodynamic processes, is The Astronomical Institute of the Charles theory of gravitational radiation, exact considered (see Figure 7 for example). University, which is an integral part of the solutions of Einstein’s field equations and Study of relativistic astrophysics includes Faculty of Mathematics and Physics, has cosmological perturbation theory. accretion processes and resonances mainly educational duties in teaching in discs surrounding black holes. An ex- undergraduate and graduate courses of The Institute of Theoretical Physics and ample is shown in Figure 8 where the astronomy and astrophysics. The re- Astrophysics at the Faculty of Sciences, predicted variations of the X-ray spectrum search areas include the spectroscopic Masaryk University in Brno, provides ba- of an accretion disc at eight successive properties of hot stars, particularly in sic courses in astronomy and astrophys- phases are plotted during the entire orbit binaries and multiple systems, and explo- ics at the undergraduate and graduate of a single spot located at a distance of ration of the nature of Be stars. Stud- level. Research includes the physics of seven gravitational radii from the black ies of physical properties, dynamics and hot stars, non-LTE models of stellar at- hole and rotating clockwise. A distant ob- evolution of small bodies of the Solar mospheres, variable stars, carbon stars, server is placed at an inclination of 30 de- System include the Yarkovsky effect and K-type giants and properties of atmos-

The Messenger 128 – June 2007 15 15 15

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Figure 8: The predicted variations of the X-ray spectrum of an accretion disc around a galactic nucleus black hole are plotted. (From Goosmann R. W. et al., in “The X-ray Universe 2005”, edited by A. Wilson, El Escorial, Madrid, Spain, in press. pheric extinction. The Institute manages entific method by special astronomical This brief review presents the past and the Masaryk University Observatory at research. The Klet’ Observatory, which current status of astronomy in the Czech Kraví hora equipped with a 0.6-m reflec- is equipped with a 1-m telescope with a Republic, which is the starting point for tor with a CCD camera. CCD detector, has its research pro- the entrance of the Czech Republic into gramme dedicated to the astrometry of ESO. The Relativistic Astrophysics Group of the asteroids with unusual orbits and com- Institute of Physics of the Silesian Univer- ets, providing precise determination of sity in Opava is active in the fields of neu- their orbits. The main part of the work is References tron stars, black holes and cosmology. devoted to the near-Earth orbits. The Eckart A. et al. 2006, The Messenger 125, 2 The anisotropies of the CBR are explored data are provided to the Central Bureau Hadrava P. 2006, “The European Southern as well as L-CDM cosmological models. for Astronomy Telegrams of the IAU. Observatory and Czech Astronomy”, Academia, Other observatories include the Nicolaus Praha The Czech Republic can be proud of its Copernicus Observatory and Planetarium Palouš J., Vondrák J. and Šolc M. 2002, “Astronomy and Astrophysics in the Czech Republic”, in unique net of planetaria and public ob- in Brno, Štefánik Observatory and Plane- “Organizations and Strategies in Astronomy III”, servatories. Their primary goal is to pro- tarium in Prague, Rokycany Observatory, ed. A. Heck, Kluwer, 163 vide natural science knowledge to a Úpice Observatory, Valašské Mezirˇícˇí Ob- broad public and to demonstrate the sci- servatory, and others.

The Messenger 128 – June 2007 Telescopes and Instrumentation laboratory. instrumentation ching Gar- ESO the in tested being and sembled as- camera, near-IR VLT new the HAWK-I,

Photo: H. H. Heyer, ESO Telescopes and Instrumentation

FORS1 is getting Blue: New Blue Optimised Detectors and High Throughput Filters

Thomas Szeifert, Roland Reiss, Pedro 100 Figure 1: Comparison Baksai, Sebastian Deiries, Carlo Izzo, of the CCD efficiencies 90 of FORS1 and FORS2 Emmanuel Jehin, Mario Kiekebusch, before and after the re- Sabine Moehler, Kieran O’Brien, 80 spective upgrades. Black: Tektronix CCDs; Emanuela Pompei, Miguel Riquelme, 70 Gero Rupprecht, Tzu-Chiang Shen Red: FORS2 MIT CCDs; Blue: FORS1 E2V CCDs. 60 (all ESO) The dotted part indi- 50 cates the range affected by fringing (see text). QE (%) Ground-based observations in the ul- 40 traviolet part of the electromagnetic 30 spectrum are notoriously difficult owing to absorption of the atmosphere, of 20 optical elements and the poorer effi- 10 ciency of detectors. Now that CCD detectors with excellent UV response and 0 300 400 500 600 700 800 900 1000 cosmetic quality have become avail- Wavelength (nm) able, it was time to optimise FORS1 for imaging, low-resolution spectroscop- intended to follow this highly successful these two chips in the blue-UV compared ic and polarimetric observations in the example by adding similar capabilities to that of the existing Tektronix CCD, as blue-UV. As a bonus, a new set of to FORS1. The first stage in this process can be seen in Figure 1. broadband filters with very high trans- was the addition of the 1200 B VPHG mission and carefully defined filter that opened new opportunities for stellar The significant boost in the quantum bands were installed. and extragalactic observations by dou- efficiency of these CCDs has been bling the spectral resolution at very high achieved by subjecting them to a treat- grism throughput. ment of soaking in synthetic air, com- FORS – A brief history bined with UV light flashing. The precise physics of this effect is not known, how- FORS1 and FORS2 are two of the first- The upgrade ever, the effect is reproducible and suf- generation VLT instruments that were ficiently long-lived so that it can be ap- built by an external consortium (Landes- Following the purchase of the VPH grisms plied to an instrument in regular science sternwarte Heidelberg, Universitätsstern- and the success of the new red detector operations. For a description of the proc- warte München and Universitätsstern- mosaic of FORS2, it was clear that an ess see Baade et al. (2005). Additional warte Göttingen, all in Germany). FORS1 upgrade of FORS1 with a blue-sensitive reasons for choosing these new detec- was the first of the scientific facility instru- new mosaic would be a good comple- tors are that they can be read out much ments and saw first light at the Casse- ment to FORS2. The prospect of having faster and have a lower read-out noise grain focus of VLT-ANTU, on 15 Septem- the same detector format for both in- level, which is crucially important for dark- ber 1998 (Appenzeller et al. 1998). FORS2 struments was another strong driver: it al- time spectroscopy and narrow-band im- followed in 2000 on VLT-Kueyen. The lows essentially the same control and aging in the blue and UV. Finally the cos- FORSes also served on Melipal and data-reduction software to be used with metic quality of these detectors is far Yepun; currently they are installed again FORS1 and FORS2. When the hardware superior to that of the generation of the on Antu (FORS2) and Kueyen (FORS1). and the resources to carry out the up- Tektronix detector used up to now with They are amongst the most scientifically grade became available, we seized the FORS1. productive instruments of the VLT: more opportunity. than 750 refereed papers have been The properties of the new CCD mosaic published to date with both FORSes. The Garching Optical Detector Team are: 4096 by 4096 pixels, 15 µm square, Many of these papers have achieved high (ODT) prepared the hardware part of the binned 2 × 2 by default. The pixel scale is scientific impact factors as indicated by upgrade, a pair of E2V blue-sensitive 0.25? per (binned) pixel and the inter-chip nearly 20 000 citations. chips. ODT was in particular responsible gap width is 12.2?. The read-out noise for the selection and characterisation as measured during the commissioning is Soon after it entered regular science op- of the CCDs, the mounting and adjust- about three electrons. erations, FORS2 received a major up- ment of the mosaic and the preparation grade when its original 2k × 2k Tektronix of the detector control system (FIERA). Strong support came from the Garching detector was replaced (effective April The CCDs are named “Marlene”, former- Integration and Cryo-Vacuum Depart- 2002) by a mosaic of two red-optimised ly the detector in the UVES blue arm, ment that prepared the cryostat and the MIT/LL CCDs. Further upgrades included and “Norma III”, one of the CCDs from various mechanical pieces required several prototype volume-phased the batch procured for OmegaCAM. for the upgrade. An important part of the holographic grisms (VPHG) that greatly The choice was motivated by a dramatic upgrade was the adaptation of the var- boosted its scientific productivity. We increase in the quantum efficiency of ious pieces of software affected by

The Messenger 128 – June 2007 Telescopes and Instrumentation Szeifert T. et al., FORS1 is getting Blue

the upgrade: Observation Software (OS), Figure 2: Old (left) templates and the Observer Support meets new (right) – the two detector systems Software (OSS) tool FIMS. These up- side by side on their grades were done by members of the dedicated carriages Paranal software department who greatly next to FORS1 in the benefited from the fact that FORS2 al- enclosure of Kueyen. ready uses a similar mosaic and similar control software. Finally, the Exposure Time Calculator (ETC) and data-reduction pipeline had to be adapted and tested.

Installation and Commissioning was a joint enterprise of theParanal Science Operation Team and the Garching Instru- mentation Division (see Figure 2). After two commissioning runs the upgraded system was certified in early April 2007 ready for science operations. This is the reason why the upgrade was only an- 100 Figure 3: Transmission curves of the old (continuous lines) and new (dotted nounced in the Call for Proposals (CfP) 90 lines) FORS filters as measured in the for Period 80. It would however have 80 ESO Optics Lab for Bessel UBVRI and been hard to justify mothballing an excel- z. The thin and thick red lines indicate 70 lent CCD system for six months and con- the FORS1 R_BESS and the FORS2 tinuing operations with an old, inferior 60 R_SPECIAL filter, respectively. one. So it was decided to go already into 50 P79 with the upgraded system and ad- 40

just the schedule where necessary at Filter response (%) 30 short notice in coordination with the PI’s. 20 We also ordered a set of dichroic high 10 throughput filters for the U, B, V and 0 300 400 500 600 700 800 900 1000 g bands to take further advantage of the Wavelength (nm) new blue sensitivity of the mosaic. We specified a very high transmission, very 100 Figure 4: Transmission curves of the old (continuous lines) and new (dotted carefully chosen central wavelengths and 90 lines) FORS filters as measured in the full width half maximum values so that 80 ESO Optics Lab for SDSS ugriz filters. the photometric flux can be nicely trans- The thin and thick red lines indicate 70 ferred to Vega magnitudes with standard the FORS1 R_BESS and the FORS2 stars selected from Landolt (1992). Col- 60 R_SPECIAL filters, respectively. The [O i] line at 557.7 nm falls exactly in the our corrections are typically smaller than 50 gap between g and R. 0.1 magnitudes. The resulting filter set (to- 40

gether with the already existing R_SPE- Filter response (%) 30 CIAL, I_BESS and z_GUNN filters) either matches the Bessel (1990) definition 20 of the UBVRI or the Sloan Digital Sky Sur- 10 vey (SDSS; Fukugita et al. 1996) ugriz 0 300 400 500 600 700 800 900 1000 systems. The latter system has achieved Wavelength (nm) great acceptance in the scientific community due to the large impact of the SDSS. Figures 3 and 4 compare the old only, because they were not yet ready we performed a thorough characterisa- FORS1/2 filters with the new ones, the and characterised when the CfP for Pe- tion of the quantum efficiency, not only of latter manufactured by Asahi (Japan). riod 79 went out in September 2006. the detectors but also of the new filters. Note that u_HIGH, b_HIGH, v_HIGH and Observations of numerous photometric R_BESS filters are only offered with and spectrophotometric standard stars FORS1 and the R_SPECIAL filter only Let the game begin … proved that our expectations, based with FORS2. on the laboratory data, were correct. The The new detector system saw its first sky new detector alone gave an improve- The new “HIGH” filters are available with light on 30 January 2007. During a first ment of 0.8 and 0.4 magnitudes in U and FORS1 since April 2007 in Visitor Mode commissioning run lasting three nights B, respectively, and the performance

10 The Messenger 128 – June 2007 dropped (as expected) only slightly in the Filter FORS1 FORS1 FORS2 VIMOS Table 1: Zero points and instrument response for I-band. Using, in addition, the new high TEK e2v MIT e2v FORS1, FORS2 and VIMOS. Note that the VIMOS U-filter red cut-off is at 395 nm while it is at 385 nm throughput filters resulted in a spectacu- U 25.20 26.53 n/a 26.5 (0.13) (0.28) (0.27) for FORS1. Similar differences exist also for the lar gain of 1.3 mag. in U and 0.8 and other filters; therefore zero points do not allow a di- B 27.70 28.48 27.70 28.20 rect comparison of the absolute instrument res- 0.3 mag. in B and V. (0.27) (0.40) (0.27) (0.34) ponse. The instrument response in detected elec- g n/a 28.89 n/a n/a trons per incoming photon after eliminating the The response given here has been calcu- (0.39) effect of the different filter sets is given in parenthe- lated from the photometric zero points V 28.05 28.33 28.10 27.90 ses. measured during the first commissioning (0.34) (0.39) (0.39) (0.38) run, according to the following strategy. R 28.00 27.96 28.40 27.90 First we calculated the Vega flux, integrat- (0.34) (0.33) (0.42) (0.35) ed over the filter curves. From the Vega I 27.15 26.99 27.70 27.0 (0.22) (0.19) (0.37) (0.17) flux we calculated the zero points for 100 % instrument and telescope throughput in magnitudes (27.41, 29.12, 29.21, tely 700 nm, increases significantly as pixel has the same wavelength for targets, 29.18, 28.78 in UBVRI and 27.93, 29.47, compared to the old (somewhat thicker) sky and flat field lamps. The correction 29.33 and 29.90 in the ubvg filters, re- Tektronix detector and the spatial fre- should therefore be possible. In practice, spectively) for incoming photons/sec at quency of the fringes also increases however, the slightly different light path the 8-m aperture of the VLT (see Table 1). strongly. The fringing has a heavy impact of the calibration light as compared to the The overall instrument response can then on high signal-to-noise observations. telescope optical path, together with be easily derived from the measured the small flexure of the FORS instrument, photometric zero points at zero airmass. For imaging observations the fringes will prevents perfect fringe correction using Similarly the Vega zero points at 100 % remain at high amplitude in the sky back- flat field spectra. In first tests, we ob- response were calculated for the VIMOS ground, on account of its OH emission- tained signal-to-noise ratios of up to 15 at UBVRI filters (27.93, 29.37, 28.96, 29.05 line spectrum, after flat fielding with the wavelengths greater than 700 nm (see and 28.91 mag.) and for the FORS2 solar spectrum twilight flat fields. The sky Figure 5). R_SPECIAL filter (29.33 mag.). The res- background with fringes is best sub- ponse is then given in units of detected tracted by obtaining an averaged sky im- Many scientific projects with FORS1 are electrons per incoming photon including age cleaned from astronomical sources, focused on detecting extremely faint the telescope, the FORS longitudinal scaled to the sky level of the individu- objects at very low signal-to-noise ratios Atmospheric Dispersion Corrector (ADC), al exposures. More commonly observers or will concentrate on the shorter wave- the instrument optics and detector res- obtain “super flats” from the night sky length range after the blue optimisation. ponse, but not the filter transmission. airglow images observed in a jitter se- To demonstrate the performance of This response is given in parentheses in quence. While this method leads to a FORS1, Figure 6 shows a spectrum of a Table 1 and demonstrates the high per- more pleasing image with a flat sky back- z = 2.42 quasar of g = 20.4 magnitudes formance of FORS1, FORS2 and VIMOS ground, it strongly compromises the pho- which was obtained in only 15 minutes of in all filters. tometric accuracy, which better matches integration time. a continuous or solar-type spectrum than In addition the new g-band filter opens a the OH airglow spectrum. In both imaging and spectroscopy it is new observation window. It collects the mandatory to apply jitter and nodding flux from the astronomical targets over In spectroscopy, flat fields obtained with techniques to obtain good sky subtrac- a wide wavelength range were the night continuous light calibration lamps can, tion. The fringes however will not be cor- sky is very dark and the atmospheric at least partly, correct the fringes. In the- rected in the extracted spectra of science transmission is high (390 nm to 550 nm). ory the light that is detected by every targets and standard stars by the nod-

A second commissioning run (five nights in March/April 2007) finally verified the functioning of the system in all supported observing modes (imaging, long-slit Figure 5: A demonstration of fringe correction with and multi-object spectroscopy, imaging the new FORS1 detector. The top panel shows part and spectropolarimetry). of a spectroscopic (master) screen flat. The next two panels show parts of two bias-subtracted sections from 1200 s spectra taken with an offset along the slit (positions A (left), and B (right)). The two … even with some adverse effects panels below show the same parts of the spectra, now divided by the master flat (top). Fringes are There is however a significant price to only partly corrected by the continuous light screen pay for high quantum efficiency in the flat fields. The difference image of these two exposures (bottom) still contains significant sky back- blue-UV: the fringe pattern at near-infra- ground flux. A better result could be achieved using red wavelengths, beyond approxima- a sequence of four exposures (A-B-B-A).

The Messenger 128 – June 2007 11 Telescopes and Instrumentation Szeifert T. et al., FORS1 is getting Blue

ding technique. More details on this topic 6 will be available on the FORS web pages. SDSS J090847.08+010114.1 It should be noted that FORS2 has extraordinarily low fringe amplitude with its red-optimised MIT detector combined 4 with the very low flexure it shares with its twin, FORS1. Users with strong require- /sec) ments on fringe correction are therefore – encouraged to choose FORS2. Flux (e

2 In summary, the successful blue upgrade of FORS1 leads to a very promising complement to FORS2 that will further enhance the scientific productivity of 0 this efficient and reliable pair of instru- 400 500 600 700 800 ments. Wavelength (nm)

Acknowledgements References Figure 6: Extracted, airmass-corrected spectrum of the quasar SDSS J090847.08+010114.1 (20.4 mag in We are grateful to: the FORS Instrument Opera- Appenzeller I. et al. 1998, The Messenger 94, 1 g-band, z = 2.42). Note that the spectrum (exposed tions Team (ESO) for continuous support through all Baade D. and the Optical Detector Team 2005, in for 15 minutes during dark time without order sepa- stages of the upgrade project: Magda Arnaboldi, “Scientific Detectors for Astronomy”, eds. J. E. ration filter) is also shown in the red and near-infrared Paul Lynam, Palle Møller, Ferdinando Patat, Marina Beletic, J. W. Beletic and P. Amico, Astrophysics spectral range where the fringes are strongest. The Rejkuba; the PAO Engineering Department for effi- and Space Science Library, Springer, 73 strongest three emission lines (from left to right) are cient support during the commissioning, in particu- Bessel M. S. 1990, PASP 102, 1181 the hydrogen Lyman alpha line, C iv and C iii] lines. lar Roberto Castillo and Pascal Robert; and finally Fukugita M. et al. 1996, AJ 111, 1748 Walter Seifert (Landessternwarte Heidelberg) for his Landolt A. U. 1992, AJ 104, 372 support in the definition of the new filter set.

VLT FORS1 image of the bubble nebula N76 around the hot binary star AB7 in the Small Magellanic Cloud, based on three exposures through narrowband filters isolating doubly ionised helium (He ii, in blue), doubly ionised oxygen ([O iii], in green) and singly ionised hydrogen (H-alpha, in red). The image measures 400 by 400 arcseconds and north is up and east to the left. The binary system AB7 (the bright stellar image in the centre of the nebula) consists of one evolved massive Wolf-Rayet star and a companion O-type star. The very high temperature of the stars is responsible for the centred He ii nebula (blue region enclosed within the yellower ring). To the north-east, just outside the nebula, a small network of green filaments is visible, a remnant of an earlier supernova explosion. See ESO PR 08/03 for more details.

12 The Messenger 128 – June 2007 Telescopes and Instrumentation

Towards Precision Photometry with FORS: A Status Report

Wolfram Freudling, Palle Møller, to characterise the photometric perform- tion revealed that the structure in the Ferdinando Patat, Sabine Moehler, ance of the FORS instruments and inves- flatfields consists of a temporally constant Martino Romaniello, Emmanuël Jehin, tigate if and how the routine calibration of pattern, superimposed on large-scale Kieran O’Brien, Carlo Izzo, the instruments can be modified to offer fluctuations which rapidly change in time. Eric Depagne, Emanuela Pompei, improved photometric zero points (ZPs). The contrast of the constant pattern Dominique Naef, Gero Rupprecht, An additional goal of this programme is to is higher in bluer bands. Interestingly, we Arto Järvinen (all ESO) develop procedures to allow users to get found a correlation of some of the pat- more accurate photometric calibration. terns with the adaptor rotator angle. The FORS instruments are mounted on The two FOcal Reducer and low-dis- The results are available as two internal adapter rotators which compensate for persion Spectrographs (FORS) are ESO reports, Møller et al. (2005) and the sky-field rotation inherent to the VLT the primary imaging instruments for the Freudling et al. (2006). In this article, we alt-azimuth mounting. Part of the struc- VLT. Because they are not direct present a brief overview of the issues re- ture in the flat field rotates rigidly with imaging instruments, the accuracy of lated to photometry with the FORS in- the angle of the rotator. This is illustrated photometry which can routinely be struments, and the current status of FAP. in Figure 1. This pattern in the flatfield obtained is limited by significant sky Our work has so far concentrated on must be external to FORS1 and might be concentration and other effects. This the FORS1 camera, but the most of the due to reflections and/or asymmetric article reports on the progress of findings will equally apply for FORS2. vignetting within the telescope or the a long-term project to improve the adapter itself. photometric calibration of the FORS instruments. Relative photometry with FORS1 A high signal-to-noise version of the rotating structure is shown in Figure 2. This Accurate photometry starts with reliable image was created by counter-rotating The calibration plan for the FORS instru- and stable flatfielding. We used the B flatfields by an amount equal to the ro- ments calls for observations of photo- huge collection of twilight flats in the VLT tator angle and then computing the me- meric standards in each clear night. The archive to investigate the quality of the dian of the rotated flatfields. If there was primary purpose of these observations flatfields commonly used for the reduc- no correlation between the structure is to monitor instrument performance. tion of FORS images. In order to investi- The same data are also used to calibrate gate the stability of the flatfields, we science observations for programmes computed the mean of bias-subtracted Figure 1: A sequence of B FORS1 sky-flats divided where 5 to 10 % photometric accuracy is flatfields, and divided each individual by the median of all flatfields. The intensity scale range is 3 %. The rotator adapter angles (−105, −73, sufficient. Two years ago we started the frame by this mean. This removed the −35, 0, +30, and +70) are indicated by a blue arrow FORS Absolute Photometry (FAP) project stable part of the flatfields. Visual inspec- in the upper right corner.

The Messenger 128 – June 2007 13 Telescopes and Instrumentation Freudling W. et al., Towards Precision Photometry with FORS: A Status Report

in the flatfields and the rotator angle, then tions from our dithered observations. The the structure of the individual flatfields details of the formalism are described should average out and the median would in Freudling et al. (2007). This image can be smooth and flat. Instead the opposite then be used to correct the flatfield, or can be seen in Figure 2. A finger-like pat- be applied as a second-order flatfielding tern, which is already visible in the indi- step to the science data. The flatfield cor- vidual flats shown in Figure 1, stands out rection frame for the R filter is shown with increased signal-to-noise. This dem- in Figure 3. The peak-to-peak flatfielding onstrates that this is a rotating feature. error at the position of the observed stars The peak-to-peak amplitude of the pat- is about 30 mmag. It should be empha- tern in the median frame is about 1%. In- sised that the amplitude of the correction spection of individual images in the stack frame depends on the flatfield used to shows that the amplitude varies substan- process the imaging data, and that the tially among the individual flatfields. correction frame therefore only applies to that particular flatfield. Twilight flats, as routinely obtained each night, differ from each other by as much We tried several methods to remove as 5 %. If such flatfields are applied to Figure 2: A stack of all B sky flats after applying a the fluctuating and rotating features, science data, the relative photometric ac- rotation around the geometrical centre with an described above, from the master flats amplitude equal to the adapter rotator angle. The curacy is limited to about 5 %. Even when intensity scale range is 1%. before computing the correction frame. controlled for rotator angle, flatfields dif- The most successful approach was to fer from each other by an amount which sitions across the CCD. This approach remove the large-scale pattern by divid- questions the feasibility of per-cent-level is often nicknamed the “1000 points of ing each flat-field by a smoothed version photometric accuracy with FORS1. A key light” approach. In addition, we took im- of itself. This procedure lowers the am- question is whether these fluctuations ages of the same fields rotating the whole plitude of the necessary correction to the reflect true differences in the end-to-end frame. flat-fields derived from observations of throughput of FORS1. In that case, rel- standard stars, and therefore improves ative and therefore absolute accuracy at Ideal data sets for calibrating images with the overall flat-fielding. the per cent level simply cannot be ob- suspected ZP variations across the de- tained with FORS1. A more likely explana- tectors are fields which contain suitable So far we have derived flatfield correction is that the flatfields are flawed and do photometric standards over the whole tions for three data sets taken more than not represent the throughput of FORS1. dithered region. We therefore selected re- two years apart. The overall shape and In that case, the task is to find the true gions within Stetson fields (Stetson, 2000, amplitude of the correction frames were flatfield which should be applied to data 2006) as our targets, which contain a stable over that period. We therefore so that the photometric ZPs are constant large number of photometric standards conclude that the best flatfielding with over the whole detector. suitable for 8-m-class telescopes. These FORS1 can be obtained by: (1) remov- fields proved to be useful for our pur- ing large-scale features from the master We experimented with different proce- pose, and we will investigate whether all flats; (2) applying a correction frame de- dures to remove the large-scale pattern current FORS calibration fields can be rived from observations of standard from the raw observed flatfields. For the replaced with appropriately selected point- fields. investigations described in the follow- ings within the Stetson calibration fields. ing sections, we used new observations to test the quality of the flatfields con- The simplest and most direct way to in- Absolute photometry with FORS1 structed in this manner, and compared vestigate relative ZP changes with them to the regular “master flats” pro- dithered data is to compare the relative Nightly ZPs for FORS instruments have duced by combining the routine twilight instrumental magnitudes of individu- so far been computed assuming a con- flats for that night. al standard stars which are observed stant extinction for each night. The ex- at positions all across the detectors. tinction, however, varies substantially The large variation in the flatfields was A much more sensitive method is to use from night to night, even when the nights the motivation to take a closer look at the measured magnitudes of any star are photometric. Therefore, ZPs derived possible variations of the ZP magnitudes which has been observed at two or more using a mean extinction depend on the across the detector when using the mas- different dither positions. Each individ- airmass of the measured standard field ter flat. The goal was to derive a correc- ual star might only provide relative ZP and are not useful for accurate photom- tion for the master flats and to find a shifts for a few positions on the detector. etry. The true instrumental photometric quantitative estimate of the accuracy of By combining the information from many ZP above the atmosphere, as derived the finally adopted flatfield. For that pur- stars, the ZP variations over the whole from extrapolation of the extinction curves, pose, we observed standard fields with a detector can be reconstructed. We used probably varies much more slowly than 25-point dither pattern which placed singular value decomposition (SVD) to the night-to-night variations of the extinc- one relatively bright star on a grid of po- construct such an image of the ZP variation. Therefore, better photometric ac-

14 The Messenger 128 – June 2007 curacy can be obtained by fitting the ex- Figure 3: R-band flatfield tinction coefficients for several nights correction frame. simultaneously, assuming that the instrumental ZP does not change. Such a scheme can be included in the computa- tion of the flatfielding correction, so that a photometric solution is simultaneously obtained with the relative flatfield correction.

The measured magnitudes of repeatedly observed stars can also be used to estimate short-term fluctuations in the extinction during the night. Each of the more than 1000 individual stars observed with our dither pattern can be used for this purpose. When the weighted average of all stars is used, changes in the extinction can be measured with an accuracy of about 1 mmag. An estimate of fluctuations in the extinction is an automatic by- product of the fitting procedure described Figure 4: Upper panel: Residuals from 40 above. the extinction solution as a function of the estimated magnitude error. The 20 magnitude error includes the mea- One of the tools to independently assess surement error from the current obser- the quality of the night is the “VLT As- 0 vations as well as estimated uncer- tronomical Site Monitor” (ASM) which can tainties for the magnitudes of standard stars. Lower panel: The variance of

Residuals (mmag) –20 be accessed at http://archive.eso.org/ the residuals as a function of magni- asm/ambient-server. We found that, tude error. The superimposed line is at least in the one photometric night used –40 an error model, which includes statisti- for FAP, the measured scatter of about cal errors as well as extinction fluctuations. 6.8 mmag is very similar to the flux rms 30 measured by the ASM monitor. It is tempting to conclude that the rms from 20 the ASM can be used as a proxy for expected rms fluctuations of the ZP. We plan to further investigate the useful- Variance (mmag) 10 ness of the ASM to judge the photometric quality of the night. 0 0 5 10 15 20 σ (mmag) Understanding the achievable accuracy m of photometry requires understanding the total error budget. In particular, it is different nights. Above, we estimated that accuracy. The uncertainty in the photo- important to understand the accuracy of extinction fluctuations during the photometric ZP is obviously an important factor our procedures for flatfielding. We used metric night for this programme were which determines the final accuracy of the residuals of the extinction solution for ≈ 6.8 mmag. In Figure 4 we demonstrate the magnitudes. The FAP observations a detailed investigation of the error esti- that extinction variations, statistical errors contain a large number of standard stars mates. and errors in the standard magnitudes on each individual image, and the num- account for most of the residuals of our ber of calibration images is much larger Measurement errors were computed for photometric solution. A detailed analysis than the number realistically taken for each measured magnitude from the suggests an upper limit on residual flat- the calibration of normal science obser- read-out and Poisson noise, both for the fielding and other sources of errors of vations. An important part of the photo- pixels used to compute the stellar flux about 3 mmag. This demonstrates that metric guidelines will therefore be to and for those used to estimate the local precision photometry with per-cent-level find the necessary minimum number of background. The error estimates range accuracy is indeed possible with FORS1. standard fields needed to achieve a cer- from 2 to 30 mmag. Errors in the listed tain photometric accuracy. standard magnitudes were taken from One of the important goals of this project Stetson (2000) and Stetson (2006), which is to define a set of guidelines on how FAP imaged four different Stetson fields are based on repeated observations in to achieve a per-cent-level photometric in a single photometric night, which were

The Messenger 128 – June 2007 15 Telescopes and Instrumentation Freudling W. et al., Towards Precision Photometry with FORS: A Status Report

used to derive a photometric extinc- the strategy outlined above, leads to an during those two months will therefore tion solution. The magnitude and colour accuracy for the magnitude ZP of about serve to determine the best possible, and range, and the consistency of derived 10 mmag. final, photometric characterisation of the ZPs is similar for all fields. To estimate the now retired system which has been used errors on the ZPs from sets of only two The scatter in the ZPs also suggests that since the start of VLT operation. standard field observations, we recom- errors are almost Gaussian when three puted the ZPs from subsets of the FAP different standard fields are used. The er- This “Final Effort” on the retired FORS1 data. We used every combination of two ror budget discussed above implies that photometric system will also serve as a standard fields which were taken with the dominant error on the mean magni- model for the design of our future FORS a difference in airmass of at least 0.7. tude of all stars in any of the standard calibration plan. Our pilot programme The distribution of the resulting ZPs is fields are fluctuations in the extinction, if has shown that per-cent-level photometry shown in Figure 5. The distribution has the number of standard stars in each with FORS is indeed feasible. The key an almost Gaussian peak but also a long field is large enough and the exposures requirement for this is the ability to com- non-Gaussian tail. In about 10 % of all sample the airmass between 1 and 2 uni- pute the flatfield corrections. In order cases, the errors on the resulting ZPs is formly. For a typical magnitude uncer- to make this possible for a large number larger than 3%. This shows that the tainty of 10 mmag, about 30 or more of programmes, those corrections must observation of only two standard fields is standard stars per field are needed. This be determined directly from the calibra- insufficient to photometrically calibrate a is one of the reasons to use the Stetson tion plan data, which in turn places more night to per-cent-level accuracy. standard fields as opposed to fields with demands on our calibration plan. In par- fewer stars with known magnitudes. ticular there needs to be a large number We then repeated the experiment using of moderately faint standards in each field. three standard fields. At most one of We are currently investigating whether the fields in each set was at an airmass The past and future FORS1 photometric appropriate regions for this purpose can less than 1.3, and the differences be- systems be found within the Stetson standard tween minimum and maximum airmass fields. Using these fields will therefore was larger than 0.7. The resulting distri- In April 2007 FORS1 was upgraded with require that we measure U-Band magni- bution of ZPs is plotted in Figure 5. Also a new CCD mosaic and a new set of tudes for the standards in those fields. shown is a Gaussian with the same broad-band filters (see article on page 9). (Stetson, 2006). mean, standard deviation and normalisa- During February and March 2007 we tion as the ZP distribution. It can be seen therefore carried out an intensified ver- FAP has shown that it is possible to that the distribution resembles closely sion of our usual photometric calibration achieve per-cent-level photometry with a Gaussian with a standard deviation of plan, where we employed all the tools FORS1 with moderate effort. Over 11 mmag. In contrast to the previous and methods developed during the FAP. the next year, we plan to prepare new experiment with only two standard fields, This data set includes dithers and rota- photometric standard fields suitable all ZP errors are less than 3 %. This result tions which makes it possible to derive to obtain more accurate photometric strongly suggests that the use of three flatfield corrections directly from the cali- solutions and simultaneously derive photometric standard fields, chosen with bration data. The calibrations obtained flatfield corrections. If this programme proves to be successful, we plan to incorporate new flatfielding algorithms Figure 5: Distributions of zero points into the FORS pipeline. determined from two and three stand- 30 ard observations (red and blue histo- grams respectively). The dashed line is a Gaussian with a s of 11 mmag. References Freudling W. et al. 2006, “The FORS Absolute Photometry Project”, VLT-TRE-ESO-13100-4006 Freudling W. et al. 2007, in “The Future of Photo- 20 metric, Spectrophotometric, and Polarimetric Standardization”, ed. C. Sterken, ASP Conference Series 364, 113 N Møller P. et al. 2005, “FORS: An assessment of ob- tainable photometric accuracy and outline of strategy for improvement (FORS IOT Secondary 10 Standards Working Group)”, VLT-TRE-ESO-13100- 3808 Stetson P. B. 2000, PASP 112, 925 Stetson P. B. 2006, fields listed at http://cadcwww. dao.nrc.ca/cadcbin/wdbi.cgi/astrocat/stetson/ query 0 27.4 27.5

16 The Messenger 128 – June 2007 Telescopes and Instrumentation

Exploring the Near-Infrared at High Spatial and Spectral Resolution: First Results from CRIRES Science Verification

Ralf Siebenmorgen1 The VLT cryogenic high-resolution infra- be used to increase both spatial resolu- Alain Smette1 red echelle spectrograph CRIRES offers tion and signal-to-noise ratio. Hans Ulrich Käufl1 high spatial, spectral and temporal Andreas Seifahrt1 resolution spectroscopy from 1 to 5 μm. The scientific potential of the CRIRES Stefan Uttenthaler 2 Highlights from among the 29 pilot instrument is demonstrated by the many Arjan Bik1 studies of the CRIRES science verifica- results obtained during three science Mark Casali 1 tion (SV) runs are summarised. verification observing campaigns which Swetlana Hubrig1 have been performed in August, October Yves Jung1 2006 and in February 2007. Twenty-nine Florian Kerber1 The VLT cryogenic high-resolution infra- pilot studies were granted observing time Jorge Melnick1 red echelle spectrograph CRIRES (Käufl totaling 20 000 s integration time. The Alan Moorwood1 et al. 2004) is located at the Nasmyth principal investigators (PI) and project ti- Jean-François Pirard1 focus A of UT1 (Antu). It provides a resolv- tles of the successfully executed SV Hugues Sana1 ing power of up to 100 000 in the spec- programmes are given in Table 1. Individ- Elena Valenti1 tral range from 1 to 5 μm. CRIRES can ual projects range from studies of the Lowell Tacconi-Garman1 boost all scientific applications aiming at Earth’s atmosphere, disc structure around Michael Hilker1 fainter objects, higher spatial resolution young stars, brown dwarfs (BD), extra- Francesca Primas1 (for extended sources), spectral and solar planets to pulsation and wind prop- Pedro J. Amado 3 temporal resolution. Spectral coverage is erties of massive stars, asymptotic giant Andrés Carmona1 maximised through a mosaic of four branch stars (AGB), structure of the Ewine F. van Dishoeck 4 Aladdin III InSb arrays providing an effec- Galaxy and astroseismology. In this arti- Cédric Foellmi1 tive 4096 × 512 detector array in the focal cle some of the highlights are presented Miwa Goto 5 plane. A MACAO (Multi-Applications in a sequence beginning with young Roland Gredel 5 Curvature Adaptive Optics) system can stars, brown dwarf stars and planets, Eike Günther 6 Bengt Gustaffson 7 Don Kurtz 8 Tabel 1: CRIRES science verification runs: principal investigator (PI) Christopher Lidman1 and project title is given for each programme. Hendrik Linz 5 Fabrice Martins 9 ID PI Title Karl Menten10 1 Amado NIR spectroscopy of pulsating stars? Claire Moutou11 2 Bik Circumstellar discs around massive young stellar objects Poul E. Nissen12 3 Carmona Probing the gas in the inner 50 AU of proto-planetary discs Dieter Nürnberger 1 4 Foellmi Distances to late-type stars 1 + Ansgar Reiners 5 Goto H3 and CO observation toward Superantennae 6 Günther CRIRES for high precision RV of late-type stars 7 Gustaffson CNO abundances in Bulge giants 1 ESO 8 Käufl Search for OH in the disc around HD 163296 2 Institut für Astronomie, University 9 Kerber Determining the atmospheric precipitable water vapour content Vienna, Austria 10 Kjaer High resolution infrared spectrum of SN 1987A 3 Gr-IAA, Instituto de Astrofísica de 11 Kurtz High time-resolution precision radial velocities of peculiar A stars Andalucía, Granada, Spain 12 Lidman A high-resolution spectral atlas of the night sky 4 Universiteit Leiden, the Netherlands 13 Linz Disc winds and envelopes associated with BN-type objects 5 Max-Planck Institute for Astronomy, 14 Martins The most massive stars in the GC: binarity and metallicity Heidelberg, Germany 15 Melnick and Gredel Molecular hydrogen in Doradus 30 6 Thüringer Landessternwarte (TLS), 16 Moutou Transmission spectroscopy of transiting extrasolar planets Tautenburg, Germany 17 Nissen The abundance of sulfur in metal-poor stars 7 Uppsala University, Sweden 18 Nürnberger Weighing a high mass protostellar candidate 8 University of Central Lancashire, 19 Reiners FeH spectroscopy in ultra-cool dwarfs – CRIRES or UVES? Preston, United Kingdom 20 Sana Can IR solve the wind clumping question? 9 Max-Planck Institute for Extraterrestrial 21 Seifahrt Effective temperatures and gravities of low-mass stars and BD Physics, Garching, Germany 22 Siebenmorgen Astrochemistry in dust formation regions 10 Max-Planck Institute for Astronomy, 23 Siebenmorgen Roadmap of astrochemistry during massive star formation Bonn, Germany 24 Siebenmorgen Bound on time dependency of the fine structure constant 11 Laboratoire d’Astrophysique Marseille 25 Smette Na i D and Ca ii in a z ~ 2 damped Lya system (LAM), France 26 van Dishoeck CO emission from transitional protoplanetary discs 12 University of Aarhus, Denmark 27 Uttenthaler The C/O and C12/C13 ratios and three dredge-up in bulge AGB stars 13 Hamburger Sternwarte, Universität 28 Uttenthaler Titanium Oxide band heads in the J-band Hamburg, Germany 29 Valenti Chemical composition of evolved populations in LMC and NGC 1866

The Messenger 128 – June 2007 17 Telescopes and Instrumentation Siebenmorgen R. et al., First Results from CRIRES Science Verification

12 followed by massive and Asymptotic Gi- 1.0 Figure 1: CO profile of the massive young stellar ant Branch stars to targets outside the object IRAS 16164-5046. From top to bottom, lines 0.8 R(7), R(4) and R(0) are plotted. The R(0) line is more Galaxy. Finally CRIRES calibration issues 0.6 sensitive to cold material than the other two. Two are mentioned. 0.4 components can be identified, one belonging to the 12 Normalised flux CO R(7) cold envelope and the other component caused by 0.2 4.6024 micron a wind or outflow (Bik et al.). 0.0 Discs around massive young stellar 1.0 objects and extrasolar planets 0.8

0.6

The known circumstellar discs around 0.4

Normalised flux 12CO R(4) massive young stellar objects T Cha and 0.2 4.6254 micron IRAS 16164–5046 were studied by van 0.0 Dishoeck [ID 26] and by Bik [ID 2], respec- 1.0 tively. The CO first-overtone emission in 0.8 the K-band probes high-temperature gas 0.6 (T = 3 000 K) and the velocity profile of 0.4 12 Normalised flux CO R(0) IRAS 16164–5046 suggests that the hot 0.2 4.6575 micron gas is located in a rotating disc within 0.0 –20 –10 0 10 20 10 AU of the central star. The CO-funda- Velocity (km/s) mental transitions in the M-band probe lower-temperature gas (T = 50–500 K) and therefore different regions in the circumstellar material. Figure 1 shows three transitions of the 12CO spectrum of IRAS 16164–5046. The R(7) line is more sensitive to higher temperature compared to RV (km/s) RV (km/s) Figure 2: Line flux and RV of the Bra –300–200 –100 0 100 200 300 –200 –100 0 100 200 R(0). The spectra reveal two absorption and Pfg (top) and various CO iso- topes (bottom) of the protostar W33a components; a saturated blue compo- (Siebenmorgen et al.). nent which could be caused by an outflow or wind, and a red, unsaturated component which changes in intensity from Brα Pfγ the higher to the lower energy level. This extra red absorption could be a cold envelope surrounding this object.

A full L- and M-band (3600–5100 nm) Normalised flux wavelength scan of the spectrum of the extremely red and massive protostar W33A was performed, aiming to achieve a first road map of the astrochemistry occurring during the formation process of 4050 4052 4054 4056 3738 3739 3740 3741 3742 3743 massive stars. A section of it, correspond- Wavelength (nm) ing to the spectral region near 4 200 nm, is shown by Käufl et al (2007). Figure 2 compares the rich CO line system (near 12C16OJ = 1–0 P7 12C16OJ = 1–0 P8

4 730 nm) to the broad Bra and Pfg lines. 13C16OJ = 1–0 R5 13C16OJ = 1–0 R4 13C16OJ = 1–0 R3 Derived radial velocities (RV) for CO, Bra and Pfg lines are ~ 31 km/s confirm- 12C18OJ = 1–0 R6 12C18OJ = 1–0 R5 12C18OJ = 1–0 R4 ing earlier estimates (Roueff et al. 2006). 12C17OJ = 1–0 P1 12C17OJ = 1–0 P2

Carmona [ID 3] obtained K-band spectra of the classical T Tauri star LkHa 264. They confirm the previous discovery of the Normalised flux ro-vibrational n = 1−0 S(1) H2 line. In addition, thanks to the enhanced sensitivity of CRIRES, they detect at 2 223.3 nm the n = 1−0 S(0) H2 transition. However, the spectra do not reveal the n = 2−1 S(1) 4725 4730 4735 4740 4745 H2 line. The line ratios of 1–0 S(0)/1–0 S(1) Wavelength (nm)

18 The Messenger 128 – June 2007 = 0.33 ± 0.1 and 2–1 S(1)/1–0 S(1) < 0.2 1.5 Figure 3: H2 n = 1−0 S(1) line detected in LkHa 264 indicate that the H emitting gas is at tem- at 2121.8 nm and model (dashed) assuming that the 2 i = 20˚ emission originates in a circumstellar disc. The fit perature below 2 000 K and most likely R = 0.10 AU min parameters Rmin and Rmax, the inner and outer radius R = 10.00 AU thermally excited by UV photons. Both max of the emitting region, a, the power law exponent 1.0 detected lines have a FWHM of ~ 20 km/s α = –2.0 of the intensity (I(R) ∝ Ra) and i, the inclination angle and are spatially unresolved. The mean (Carmona et al.), are listed. FWHM of the PSF in the continuum is

~ 0.36? in the H2 1–0 S(1) spectrum, con- 0.5 straining the H2 emitting region to the inner 50 AU of the disc at an assumed distance of 300 pc. The n = 1−0 S(1) and 0.0 the n = 1−0 S(0) H2 lines in LkHa 264 are Normalised flux – continuum single peaked. Modelling of the n = 1−0 S(1) line shape indicates that the disc has a relatively small inclination. The best –0.5 model fit suggests that the disc sur- –50 0 50 rounding LkHa 264 is inclined by 20˚ rela- Velocity (km s–1) tive to the line of sight (Figure 3). 1.2 Figure 4: Cut–out of the high-resolu- Late-type objects of spectral type M and ε Indi Ba (T1.0) tion spectrum of the binary components e Ind Ba (top) and Bb (bottom). later exhibit extremely interesting ab- 1.0 Lines of water vapour (H2O) and sorption bands. In particular, the molecu- methane (CH4) are marked. Note the increase in line strength for both spe- lar band of FeH shows sharp absorption 0.8 H O cies between the T1 dwarf (Ba) and lines that can be used for precision spec- 2 + constant)

λ CH the T6.5 dwarf (Bb) and the strong line troscopy, a rare feature for late-type stars 4 0.6 broadening by the high projected and brown dwarfs. These lines appear rotational velocity v sin i ~ 28 km/s in the spectral range close to ≈ 1000 nm, (Seifahrt et al.). 0.4 at the red end of the UVES spectral cov- ε Indi Bb (T6.5) erage and at the blue one of CRIRES. A Normalised flux (F performance test of both instruments 0.2 in this overlapping region was carried out by Reiners [ID 19] on GJ 2005A, a M5.5 0.0 star, observed with CRIRES and MACAO, 1301 1302 1303 1304 1305 1306 while Gl 406, a star of the same spectral Wavelength (nm) type, was observed with UVES. The FeH absorption of both stars resembles each ed on a K i line at 1252.5 nm, water va- has several advantages: indeed, late- other very closely. The UVES data were pour and methane (CH4) features at wave- type stars and brown dwarfs are much taken at a resolution of 50 000, and for lengths close to the peak flux of T dwarfs. brighter at infrared wavelengths while comparison CRIRES data were rebinned For the first time in natural-seeing ob- the RV-jitter caused by stellar activity is to match this lower resolution. The UVES servations, spectra of both binary com- about one order of magnitude smaller exposure of Gl 406 (V = 13.54) yielded ponents, separated by ~ 0.9?, have been in the infrared than in the optical regime a SNR of 60 after 200s whereas the obtained with spectral resolution of (Martins et al. 2006). Günther [ID 6] ob- CRIRES spectrum on the much fainter R ~ 50 000 (Figure 4). The S/N of the spec- served the M0V star GJ9847 in two dif- star GJ 2005 A (V = 15.42) gives a SNR tra are between 20–60 (per pixel) which ferent nights, obtaining spectra with the of 50 after 480 s. Therefore, in this over- is in close match to the predictions of the N2O-absorption cell, as well as tem- lapping wavelength region, UVES re- CRIRES exposure time calculator (ETC). plate spectra without. Simulations predict quires roughly twice the observing time Detailed comparison of the spectra to that the simultaneous wavelength refer- of CRIRES to reach the same SNR for synthetic atmospheric models as well as ence allows a radial velocity precision of similar flux levels and spectral resolution. to existing T dwarf models are in pro- better than 30 m/s to be achieved. Even gress. In particular, the relative radial ve- though improvements in the data analysis The closest T dwarf to the Sun (3.26 pc), locity of e Indi Ba-Bb will improve their are still possible this accuracy is already e Ind B, is an ideal system to improve our orbital parameters. achieved. The basic idea of the procedure understanding of substellar objects by is the same as for the I2-cell method in detailed spectral measurements. The two Precise radial velocity (RV) measure- the optical, which has been used for many members of this extreme cool brown ments are important in many astrophysi- years for planet detection. The main dif- dwarf binary have spectral type T1 and cal objects. In particular, they have led ference is that the influence of the telluric

T6.5 and masses of ~ 47 and 28 MJup, to the discovery of more than 200 extra- absorption lines has to be carefully re- respectively. The CRIRES spectroscopy solar planets. Carrying out equivalent moved. This is achieved by dividing the campaign by Seifahrt [ID 21] concentrat- measurements at infrared wavelengths spectrum by a reference star free of

The Messenger 128 – June 2007 19 Telescopes and Instrumentation Siebenmorgen R. et al., First Results from CRIRES Science Verification

Figure 5: From top to bottom and absorption features, e.g. a B-type star. Science target: GJ9847 (M0V) This technique is illustrated in Figure 5 for shown as indicated: the normalised spectrum of GJ9847; the telluric the M0V star GJ 9847. 2.0 standard star; the N2O gas cell; and the final composite spectrum (Günther Telluric transmission: (standard star 105 Aqr, B9V) The SV programme by Moutou [ID 16] et al.). 1.5 + offset)

aimed at detecting the absorption signa- λ ture of a planetary atmosphere, during a transit of the extrasolar planet in front of Gas cell: N2O, first overtone, R(30)–R(0) and P(1)–P(2) its parent star. This requires high spec- 1.0 tral resolution to deblend the planetary features from the stellar ones at a certain Normalised flux (F 0.5 epoch. For such transiting systems, one expects to detect a K i absorption feature Final composite spectrum in the near-IR. Unfortunately during the 0.0 2 254 2 256 2258 2 260 2 262 2 264 execution of the programme, the CRIRES Wavelength (nm) observing sequence could not fully meet the time critical window that lasted a little O-type stars are among the brightest and was achieved (Nissen et al. 2007 – more than two hours. The data however most luminous stellar components of a the first published refereed paper from show differences from one spectrum to galaxy. Through their radiation and wind CRIRES). the other and a longer lasting sequence momentum, they largely influence their + is allocated in P79. surroundings as well as their host galax- The infrared absorption spectra of H3 ies. However, our knowledge of these and CO were observed by Goto [ID 5] to- objects is still fragmentary. One of the ward the luminous infrared source in the Massive stars, Asymptotic Giant Branch currently most critical questions is related Quintuplet cluster GCS 3-2 and is shown stars and Galactic structure to the exact properties of their stellar in Figure 6. Note the distinct absorption + l winds, which determine their mass-loss profiles of H3 R(1,1) and CO R(1) along The Pistol star, located close to the Gal- rates, and thus their evolution to become the same line of sight. While CO mostly actic Centre, is the most luminous star in supernovae. CRIRES allows to signifi- probes the gas in molecular clouds in the the Galaxy. Unless it is actually made up cantly increase the number of accessible Galactic arms along the line of sight, the + l of various components, it is also the best diagnostic lines. Sana [ID 20] acquired a H3, responsible for R(1,1) , occurs both in candidate to be the most massive star. high S/N ratio spectrum of z Pup, an O4 arm clouds and in the gas at the Galac- The very high resolving power of CRIRES supergiant and one of the closest O-type tic Centre region. The pedestal compo- was used by Martins [ID 14] to investigate stars. The comparison of the observed nent of R(1,1)l is almost indentical with the the presence of a spectroscopic com- line profile with the one predicted from broad absorption band of R(3,3)l obtained panion, as well as to constrain the abun- atmospheric models should provide tight at Subaru and Gemini South. R(3,3)l how- dance of a few key elements (Si, Mg and constraints on its wind properties and, ever exclusively samples the gas in the + Fe). Data were obtained during the Febru- more specifically, on its clumping factor. Galactic Centre. The population of H3 in ary run and are currently being analysed Using ESO and IUE archives, a multi- the metastable state (J,K) = (3,3), 361 K with atmospheric models. They will re- wavelength analysis covering the whole above the ground state, attests to the veal whether the Pistol star is truly a very spectral range from the UV to the near- presence of warm (T ~ 250 K) and diffuse 3 massive star, and will provide the ratio IR domain is foreseen. The complemen- gas (NH ~ 100/cm ) in the central mo- of alpha elements to Fe, a quantity which tarity of the diagnostic lines in these va- lecular zone, which was unknown before critically depends on the chemical en- rious wavelength ranges should help (Oka et al. 2005). richment history and the IMF in the Gal- to obtain a self-consistent view of the at- actic Centre. mosphere of this massive star. Uttenthaler [ID 27] obtained H- and K- band spectra of a handful of bulge AGB Information on star interiors can be ob- Nissen [ID 17] choose extreme metal- stars to determine the C/O and 12C/13C tained through the determination of the poor stars in the Galactic halo to study ratios. These ratios are influenced by frequencies of pulsation modes as they the abundance of Sulphur, an a-element, a deep mixing event called the third emerge at the stellar surface, a technique considered an important diagnostic dredge-up (3DUP) which occurs on the known as astroseismology. Amado et for galactic chemical evolution (see the AGB. If 3DUP has occurred in a giv- al. [ID 1] tested the feasibility of astroseis- article by Nissen et al. on page 38). In- en star, the 12C/13C ratio should be high mology in the NIR. For 3.5 hours, they frared observations of atomic lines in the (compared to the solar value of ~ 89), continuously observed the strongly pho- near-infrared are an important comple- otherwise it should be low (< 10). As an tometric d Scuti variable star, 1 Mon and ment to visible (UVES) spectra, as they example the CRIRES spectrum of M794 searched for the presence of line profile can be less sensitive to details of the at- reveals a strong 12CO 4–2 band head or equivalent width variations due to the mospheric models and may have sub- but weak 13CO lines (e.g. at 2 354.25 and pulsations. stantially larger oscillator strengths. An 2355.1 nm), so that this star has a rath- impressive spectrum with a S/N of 330 er low 12C/13C ratio. Further support that

20 The Messenger 128 – June 2007 + l Figure 6: Infrared absorption spectra of H3 R(1,1) with an excess of O relative to Fe but Subaru and CO R(1) towards the Quintuplet cluster GCS 3-2 compatible with the alpha elements (Mg, 1.15 observed with three different high-resolution spectrographs. The performance of IRCS at the Subaru Si and Ca). The C and N abundances telescope (with spectral resolving power R = 20 000) are signs that matter exposed to the CN 1.1 Gemini and Phoenix at Gemini South (R = 75000) is com- cycle (which conserves the sum of C pared to that of CRIRES at the VLT (R = 100000). and N nuclei) has been dredged up to the 1.05 The higher velocity resolution of CRIRES is the obvious advantage among the other instruments on stellar surface. The sum of the abun- VLT/CRIRES 8-m-class telescopes. dances of C, N, and O is close to that ex- 1 pected from a non-processed old star, Relative intensity discriminated by obtaining the ages of formed with an excess of oxygen and 0.95 a considerable number of Bulge red giant alpha elements relative to iron. The pre- R(1,1)I stars using the ratios of heavy element liminary elemental abundances are pre- GCS 3-2 3.7155 µm 0.9 abundances, in combination with their sented in Ryde et al. (2007), while a full kinematics, as a chronometer. The main analysis will be presented in a forthcom- –200 –100 0 100 reason for observing in the IR (see Ryde ing paper. 1.5 et al. 2005) is the much smaller interstel- Subaru lar extinction so that the whole Bulge is observable and not just a few windows Outside the Galaxy transparent at optical wavelengths. Only 1.25 Gemini the near-IR offers all the indicators neces- Two extragalactic SV projects were exe- sary for accurate determination of the im- cuted. Siebenmorgen [ID 24] tried to portant C-N-O molecular equilibrium constrain variations in the fine structure 2 VLT/CRIRES in the atmospheres of cool stars, through constant, a = e /hc by observing the 1 the simultaneous observation of many [O iii] doublet redshifted to z ~ 2. The QSO

Relative intensity clean CO, CN and OH lines. The goal with 1148-001 was selected as it shows a the SV run was to test the method. The bright doublet unresolved at low resolu- CO R(1) result was successful, even though, only tion. Unfortunately, the lines are too 0.75 GCS 3-2 2.3433 µm three Bulge stars could be observed. broad when observed at a resolution of Figure 7 shows the CRIRES spectrum of –200 –100 0 100 one of them, Arp 4203. The wavelength V (km/s) LSR range 1531–1570 nm was recorded and Figure 7: Two sections of the CRIRES spectrum of only a 1/4 of the spectrum is shown for Arp 4203 are presented (full line, black) together with M794 has not experienced a 3DUP is giv- clarity. From the derived abundances, models with nitrogen increased by +0.4 dex (dashed, blue) relative to the best fit, and when oxygen is in- en by the non-detection of Technetium, the findings are that, e.g., the giant star stead decreased by 0.2 dex (dotted, red). For clarity a radioactive indicator for this process. Arp 4203 is depleted in C, enriched in N, the best-fit model is not shown (Gustaffson et al.). Interestingly, as determined from UVES spectra, this star shows Lithium in its 1.0 atmosphere, which is rather surprising for a previously classified low-mass AGB star. Most probably another mixing proc- 0.8 ess – called cool bottom processing – is at work in this star, reducing the 12C/13C ratio almost down to its equilibrium value.

Normalised flux0.6

Gustaffson [ID 7] studied the CNO abun- CN Fe Fe OH OH CN Fe+Si Ti CN Fe CNCN Ni Si+OH OH+CN CN dances in bulge giants, first, as a SV trial 0.4 15 530 15535 15540 15545 15550 15555 15560 15565 run and subsequently in an allocated pro- Wavelength (Å) gramme in period P79. The team is a large international collaboration including 1.0 members from Australia, Brazil, Chile, France, Germany and Italy. Studying the Milky Way Bulge is particularly impor- 0.8 tant and, as an ultimate goal, should answer the question of whether it is the Galaxy’s oldest region, perhaps together

Normalised flux0.6 with the Halo. Alternatively, it could have CO band head been gradually formed, at least partially, OH OHOH CN CN CN CNFe Fe Fe OH+FeCN from stars and gas in the disc that mi- 0.4 15565 15570 15575 15580 15585 15590 15595 15600 grated inwards. These hypotheses can be Wavelength (Å)

The Messenger 128 – June 2007 21 Telescopes and Instrumentation Siebenmorgen R. et al., First Results from CRIRES Science Verification

50000 and no useful constraint could be Calibration of CRIRES data: CRIRES and spection of the R ~ 100 000 spectra re- derived. the Earth’s atmosphere veals that CRIRES resolves doublets which are seen as single lines at spectral A second project focused on the ISM of Observing with CRIRES as well as cali- resolution of 10000 (see Figure 9 in proto-galaxies at z > 2 (Smette [ID 25]). brating and reducing CRIRES data re- Siebenmorgen and Smette 2007). How- The Na i and Ca ii absorption lines are vealed multiple challenges that the sci- ever, even at a resolution of 100 000 common features in the ISM of our Gal- ence verification programmes helped to CRIRES does not resolve individual lines. axy, but so far they have never been ob- identify. A large number of the problems Also, a number of sky lines appear that served in the ISM of objects with red- that the CRIRES team met during the are not listed in available catalogues and shifts larger than one. CRIRES offers the execution of the programmes have been vice versa. possibility to extend the study of the ISM solved in time for science operations, by means of these important lines for while work is still going on for others. CRIRES is also helping ESO in prepara- damped Lyman-systems (DLA) at high z. tion for the next generation of giant These lines provide important information For example, the high-resolution capabili- telescopes. Kerber [ID 9] tested a method regarding the velocity structure of the ties of the instrument are a challenging to measure the atmospheric content of gas. Na i can be compared with the low- aspect when it came to the development precipitable water vapour (PWV) using the ionisation lines seen in UVES spectra to of a precise (s(v) ~ 70m/s), robust and equivalent widths of H2O absorption lines better constrain the ionisation conditions. automatic wavelength calibration proce- in the near-IR which are imprinted onto At low redshift, Ca ii is often seen in tur- dure. The pipeline, now in use to assess the spectra of early-type stars. An accu- bulent material such as the one seen in the quality control of the data, uses as rate and efficient method to determine the merging galaxies. Comparison be- first guess the wavelength solution pro- the PWV is highly valuable for any ther- tween Na i and Ca ii is also a very good vided by a physical model of the instru- mal IR instrument at an E-ELT. For quanti- indicator of the clumpiness of the gas. ment, which is accurate to about 1–2 pix- tative measurements, unblended water The QSO HE0251-5550, chosen from els. It then cross-correlates data with lines are selected to have a minimum de- the H/ESO DLA survey (Smette et al. in other catalogues such as telluric features pendence of their absorption coefficient prep.), has a hydrogen column density computed by HITRAN or OH line lists. at a temperature of ~ 300 K. CRIRES log(NHI) = 20.7 DLA in its spectrum and a In addition, CRIRES supports high-accu- spectra of bright stars were observed on redshift of z = 2.3, allowing the search racy wavelength calibration by means several nights during SV. On some of for Na i and Ca ii doublets with CRIRES. of gas cells and a ThAr hollow cathode these nights routine measurements with Although the object is bright enough in lamp (Kerber et al. 2007). VISIR (see Smette et al. 2007) can be R-band to close the AO loop, though with used to establish the PWV from mid-IR little improvement in image quality, the But an accurate and precise wavelength data allowing for comparison across faintness of the QSO (H = 14.6) made calibration relies on a large number of wavelength and method. Very acceptable guiding somewhat difficult, as insufficient lines on each detector. Ideally, these lines agreement between both methods and flux is reflected back from the slit jaws to should be observed simultaneously with instruments is found. the slit viewer detector. The spectra cov- the target. Such is the case for observa- ering the Na i lines reached the expected tions through gas cells. In several spec- S/N but did not reveal the lines, probably tral bands, the sky lines are very numer- References because of the low metal abundance of ous. However, little is known of their Carmona A. 2007, Ph.D. Thesis, University of this system. Unfortunately, the seeing apparent wavelength stability which could Heidelberg degraded during the promising, yet chal- limit their use for high-accuracy wave- Käufl H. U. et al. 2004, SPIE 5492, 1218 lenging, observations of the Ca ii lines and length calibration. Such a study – the fea- Käufl H. U. et al. 2007, The Messenger 126, 32 the spectra have an unusably low S/N. sibility of using OH lines to calibrate Kerber F. et al. 2007, ASP Conference Series 364, ed. C. Sterken, 461 Despite the non-detection, these obser- CRIRES data – is at the base of the pro- Martins F. et al. 2006, ApJ 644, L75 vations were a good test of the feasibility posal of Lidman [ID 12], as this molecule Nissen et al. 2007, A&A, accepted, to observe such ’faint’ targets with shows a rich ro-vibration spectrum. astro-ph/0702689 CRIRES, in particular, when the high res- Before CRIRES, OH sky line spectra had Oka et al. 2005, ApJ 632, 882 Roueff et al. 2006, A&A 447, 963 olution allows one to avoid the effects of only been systematically obtained with Ryde N. et al. 2007, astro-ph/0701916 telluric lines. spectral resolutions of 10000 or less. Ryde N. 2005, in: “High Resolution Infrared Spec- CRIRES spectra of the OH lines were tak- troscopy in Astronomy”, ESO Astrophysics en during evening twilight, which is the Symposia, (eds.) H. U. Käufl, R. Siebenmorgen and A. F. M. Moorwood, Springer, 365 time when they are at their brightest. In a Siebenmorgen R. and Smette A. 2007, CRIRES single 300-s exposure it is possible to User’s Manual, http://www.eso.org/instruments/ see up to a dozen lines on a single detec- crires/doc/ tor and up to four times that number Smette A., Horst H. and Navarrete J. 2007, Proceedings of the 2007 ESO Instrument Cali- over the entire mosaic. In order to assess bration Workshop, Springer-Verlag, in press, their wavelength stability, data over sever- http://www.eso.org/gen-fac/meetings/cal07/ al nights were obtained, immediately presentations/smetteCal07.pdf followed by a ThAr spectrum. A quick in-

22 The Messenger 128 – June 2007 Telescopes and Instrumentation

The First Active Segmented Mirror at ESO

Frédéric Gonté, Christophe Dupuy, The design and integration phases of onal mirrors have to be aligned with a Christoph Frank, Constanza Araujo, APE, which started in 2005, have been precision better than 15 nm rms. It was Roland Brast, Robert Frahm, completed and the test phase will start clearly not feasible to produce a scaled- Robert Karban, Luigi Andolfato, in June 2007 during which time APE down version of the full primary mirror. Regina Esteves, Matty Nylund, will be installed at the focus of one of the However, from a statistical point of view, Babak Sedghi, Gerhard Fischer, Lothar VLT unit telescopes in 2008. a mirror with approximately 50 segments Noethe, Frédéric Derie (all ESO) is already representative of a mirror with Initially the APE team wanted to contract many more segments in terms of the the design and manufacture of the ASM study of issues like alignment algorithms The Active Phasing Experiment (APE) is to a private company. However, when or the effect of misalignments on image part of the Extremely Large Telescope no company could be found which could quality. The main requirements for the Design Study which is supported by the meet the rather stringent requirements, ASM can be summarised as: European Framework Programme 6. it was decided to develop the ASM in- – 61 segments in four rings around the This experiment, which is conducted in house, involving ESO groups in Integra- central segment collaboration with several partners is tion, Optics, Electronics, Software and – Segment size 17 mm to minimise the a demonstrator to test and qualify newly- the ELT Project Office. size of the re-imaged pupil and developed phasing sensors for the align- the relay optics on the optical bench ment of segmented mirrors and test – Three degrees of freedom for rigid body the phasing software within a telescope Design and integration movements, that is piston, tip and tilt control system to be developed for a for each segment future European Extremely Large Tele- The current design of the primary mirror – Precision of displacement better than 2 scope. The segmentation of a primary of the European Extremely Large Tele- nm (similar to an ELT) mirror is simulated by a scaled-down scope consists of 984 hexagonal seg- – Range of displacement more than Active Segmented Mirror of 61 segments (Gilmozzi and Spyromilio 2007). 15 μm (similar to an E-ELT) ments which has been developed in- Each segment has a diameter of around – Size of the gaps between segments house. 1.5 m and the size of the gaps between between 80 and 150 μm (scaled-down the segments is approximately 4 mm. from the gap size in the ELT primary) In order to achieve the performance re- – Surface form quality better than 15 nm Background quired for high-resolution imaging with RMS (similar to the required surface extreme Adaptive Optics (AO), the hexag- quality of a real segment with active In order to gain experience with the phas- shape control) ing of segmented mirrors, in particular – Operational temperature between 0˚C to develop new optical phasing sensors and 25˚C and to test the interface with the rest of – Possibility to exchange a segment in the wavefront control system, ESO de- case of failure. cided to perform an optical-bench type – Optical fibres to be inserted in two of experiment, named the Active Phasing Photo: H. H. Heyer, ESO the hexagonal mirrors (central mir- Experiment (APE). This project is part of ror and one of the perimeter mirrors) to the Extremely Large Telescope Design align APE with high efficiency Study (ELTDS) which is supported by the European Framework Programme 6. The A segment unit, shown in Figure 1, con- project is performed in close collabora- sists of a base, three actuators, three tion with the Istituto Nazionale de Astro- springs and a hexagonal mirror. The 61 fisica di Arcetri, the Instituto de Astrofísica modules were assembled on a base plate de Canarias (IAC) and the Laboratoire (Figure 2). Since the precision of position- d’Astrophysique de Marseille (LAM), and ing the surfaces of the hexagonal mir- the industrial firm Fogale. The core optical rors relative to the base plate is better element of APE, simulating the segment- than 15 µm, it is necessary to be able to ed primary mirror in a large telescope, is actively align all the mirrors. Among the a scaled-down Active Segmented Mirror set of candidates for the commercially (ASM) with 61 segments which can all available actuators, only piezo actuators be controlled in piston, tip and tilt. The could fulfil the ASM requirements. Since pupil of the telescope is re-imaged onto this type of active segmented mirror is the ASM. The optical beam is then re- the first of its kind it was decided to start adapted to behave like the VLT output development in mid-2005 with a proto- beam and distributed to the four phasing type of only seven segments. sensors to be tested in the experiment. Figure 1: Each segment is integrated separately. It is composed of one base, three piezo-actuators, three springs and a hexagonal mirror.

The Messenger 128 – June 2007 23 Telescopes and Instrumentation Gonté F. et al., The First Active Segmented Mirror at ESO

Figure 3: Integration of the ASM (having a plug and play concept) by Christophe Dupuy. Each segment is added one by one on a support

Photo: H. H. Heyer, ESO polished plate which has a surface flatness better than 2 microns.

Figure 2: Mechanical design of the ASM made by Christoph Frank. The 61 segments are seen with the three actuators per segment, the module base, the support plate and the connectors behind the support plate. The fibres inserted in the central mirror and one of the mirrors on the right side of the Figure 4: Photo of the ASM can also be seen. fully assembled ASM. Photo: H. H. Heyer, ESO

The mechanical design has been made by Christoph Frank. The integration has been conducted by Christophe Dupuy for the opto-mechanical parts (see Figure 3), by Roland Brast for the drive electronics and by Robert Frahm for the software. The tests were performed by Constanza Araujo. Information obtained during the tests of the seven-segment prototype was used to improve the final design.

obtained by an Internal Metrology sys- Current tests tem which consists of a two-wavelength interferometer developed by Fogale. Several features have been tested on the The seven-segment prototype has been fully integrated ASM (Figure 4), for exam- used to test the closed-loop system ple fatigue of the components, eigen- and achieved a performance better than frequencies, speed and hysteresis of the 5 nm rms for the alignment errors at the positioning, drift of an actuated position, intersegment borders. resolution and accuracy of the positioning, quality and cosmetics of the surfaces The fully integrated ASM has now fulfilled of the segments. The fully integrated ASM and, in some areas, even surpassed the has fulfilled and, in some cases, even sur- specifications. The success of this realisa- passed the specifications. Figure 5 shows tion now provides the possibility to fully an interferogram of the surface of the test future phasing sensors of the E-ELT ASM while being tested. The tips and tilts within the Active Phasing Experiment. of the segments have been selected such that the letters of the acronym ASM appear in the interferogram. References Figure 5: Interferogram of the surface of the ASM. Some segments have been tip-tilted to create fringes Gilmozzi R. and Spyromilio J. 2007, The Messenger on some selected segments to write on it the During the APE experiment, the ASM will 127, 11 acronym ASM. be driven in closed loop based on signals

24 The Messenger 128 – June 2007 Telescopes and Instrumentation

Progress of the ALMA Project

Figure 1: The Road between Chilean High- way No. 23 and ALMA. Christoph Haupt, Hans Rykaczewski (ESO)

AOS Site (43 km) An overview of the current status of the OSF Site (15 km) ALMA project and the progress over the Photo: H. H. Heyer, ESO last two years is presented. The main focus is on the European deliverables, but the contributions of North America and Japan are also mentioned.

Science Objectives of ALMA

The Atacama Large Millimeter and Sub- millimeter Array (ALMA) will provide an unprecedented combination of sensitivity, angular resolution, spectral resolution, and imaging fidelity at the shortest radio wavelengths for which the Earth’s atmos- tely, the results of testing of the proto- in ALMA is expected by summer 2007. phere is transparent. The three major types for the receiver cartridge showed With the inclusion of the Japanese scientific goals for ALMA can be summa- that several of the receivers significantly partners ALMA becomes a truly global rised as: to detect spectral line emission exceeded their noise temperature re- astronomy facility. from CO or C ii at a redshift of z = 3 in quirements, thus partially offsetting the less than 24 h of observation; to image loss in sensitivity through the reduced gas kinematics in protostars and proto- number of antennas. Independent advi- The ALMA Site planetary discs at a distance of 150 pc, sory and review committees, focusing on enabling the study of the physical, chemi- the technical performance as well as on The ALMA Array Operations Site (AOS) cal and magnetic field structures; to pro- the cost of the project, confirmed the sci- will be located at a unique place: the Alti- vide images with an angular resolution of entific importance of the modified ALMA plano de Chajnantor, a plateau at an alti- 0.1?. project, based on the new affordable tude of 5 000 metres in the Atacama Des- costs. By the end of 2005 the re-base- ert in Chile. This location was selected for lined project and the new budget were reasons of dryness and altitude. Developments over the last two years approved by the ESO Council. The North American partners received approval The ALMA Operations Support Facili- The agreement to construct ALMA was from their Funding Agency (NSF) by the ties (OSF), located at an altitude of about signed in 2002 by the North American middle of 2006. 2 900 metres and 28 km away from the community, represented through the Na- AOS will be the base camp for the every- tional Science Foundation (NSF), and In parallel, Japan, through the National day, routine operation of the observatory. the European community, represented Astronomy Observatory of Japan (NAOJ), through ESO. After three years of detailed continued to define and formulate their Constructing and operating the ALMA design studies and prototype research, participation in the ALMA project. The Observatory within the ambitious sci- it became evident that the project could European and North American partners entific goals and the unprecedented tech- not be realised within the original time- in ALMA spent a considerable amount of nical requirements in this environment, scale and within the available funds fore- time with their Japanese partners in iden- with its harsh living conditions, will be one seen at the time of signing the agree- tifying the Japanese participation and of the real challenges. ment. The management and scientists reviewed various subsystems, in particu- involved in ALMA were therefore charged lar correlator, receivers and antennas. Construction of the OSF and AOS sites to develop a new configuration of the Details on the partnerships were defined and their access required substantial project within their foreseen budget, while and an official, trilateral agreement be- effort from the ALMA project. The OSF still maintaining the prime scientific objec- tween ESO, the NSF, and the National In- site, located at 2 900 metres altitude, is tives. stitute for Natural Sciences (NINS, Japan) about 15 km away from the nearest pub- was signed in summer 2006. NAOJ will lic road, the Chilean highway No. 23 During this period in-depth studies and provide four antennas of 12 metres diam- and the AOS is another 28 km away from large efforts were made to define the “re- eter, twelve antennas of 7 metres diame- the OSF site. A road of 43 km length baselined” ALMA project. A major ele- ter, two receiver bands for all 66 anten- was constructed to access the OSF and ment in cutting the cost was the reduc- nas of ALMA and the Atacama Compact AOS (Figure 1), with sufficient width to tion of the number of antennas from 64 to Array (ACA) Correlator. Approval of funds regularly transport the antennas between 50 (with an ultimate goal of 64). Fortuna- required for the Japanese participation the OSF and AOS for maintenance.

The Messenger 128 – June 2007 25 Telescopes and Instrumentation Haupt C. and Rykaczewski H., Progress of the ALMA Project

Figure 2: Construction work on the OSF Technical Buildings. The OSF is the centre of activities of the ALMA construction project. Presently all ALMA Site contractors and their staff are accommodated at the OSF. Work is organised in 20 day working/10 day rest periods. Special camps have been erected and can now accommodate the maximum required capacity of 500 work- ers.

During the construction period, the OSF will become the focal point of all antenna Assembly-Integration-Verification (AIV) activities. Antenna assembly will be done at the OSF site at three separate areas, one each for the antennas provided by North America (Vertex), Japan (Melco) and Europe (AEM Consortium). AIV activities will be carried out at the OSF, after preliminary acceptance of the antennas, and prior to moving them to the AOS.

Ultimately, the OSF and its Technical Fa- cilities will become the centre of all day- to-day scientific activities. During the operations phase of the observatory it will be the workplace of the on-site astronomers and of the technical teams responsible for maintaining proper functioning of the ALMA telescope and its equipment.

ESO signed the contract for the construc- Figure 3: The AOS tion of the OSF Technical Facilities in Technical Building. August 2006. Construction work has advanced (see Figure 2) and during this The ALMA Antennas prototypes were extensively tested at the time no major problems or delays have ALMA Test Facility in Socorro, New Mex- occured. As specified in the construc- Major performance requirements of each ico (see the image on the front cover). tion schedule, foundations have been antenna are 2? absolute pointing over the Various groups of international experts, prepared and the superstructures of the whole sky, 0.6? offset pointing, a 25 mi- both internal and external to ALMA, re- buildings were completed in March 2007. cron rms overall surface accuracy and viewed the performance of the prototype Provisional Acceptance of all facilities the ability to fast switch over a 2-degree antennas and concluded that the per- is foreseen for the first quarter of 2008. range in less than 1.5 seconds. These re- formance expected at the ALMA site con- quirements are at least comparable to forms to the technical requirements for all The AOS Technical Building (Figure 3) will those of existing submillimetre radio tele- three designs. be delivered by the North American ALMA scopes; however all of these, except the partner. Inside the building, construction APEX antenna which is very similar to an Following a Call for Tender for the anten- work and furnishing is expected to be ALMA prototype antenna, are protected nas, the North American partners of the completed by summer 2007. Human op- from the weather by shelters. ALMA project, through Associated Uni- erations at the AOS will be limited to versities Incorporated (AUI), signed a con- an absolute minimum, due to the high alti- The antennas are critical for the ALMA tract to supply up to 25 antennas, with tude. The AOS Technical Building will project and their quality and performance options to increase the contract to 32 an- house the Back-End electronics and the are a major contributor to the overall tennas, with Vertex RSI on 11 July 2005. Correlator. Digitised signals received functionality of ALMA. In view of the tech- Similarly, on 6 December 2005, the ESO from the radio telescopes will be proc- nical criticality of the antenna specifica- Director General signed a contract (see essed here and further transmitted to the tion, three prototypes were supplied by ESO PR 31/05) with the AEM Consor- data storage facilities located at the the AEC Consortium (procured by ESO), tium (Alcatel Alenia Space France, Alcatel OSF. The AOS building will become us- Vertex RSI (procured by NRAO for North Alenia Space Italy, European Industrial able for installing technical equipment in America) and Mitsubishi Electrical Com- Engineering S.r.L., MT Aerospace) for the June 2007. pany (procured by NAOJ, Japan). All three supply of 25 ALMA antennas (as the Eu-

26 The Messenger 128 – June 2007 Figure 4: ALMA Antenna Transporter. ropean share of the project), also with options to increase the number of antennas to 32. The four total power antennas of 12 m diameter, equipped with nuta- tors, to be provided by Japan, have been ordered from Mitsubishi Electrical Com- pany. The twelve remaining antennas of 7 m diameter will be ordered in the course of the year 2007 by NAOJ. Photo: Scheuerle Fahrzeugfabrik GmbH

The first antenna to be supplied by Vertex RSI is expected to be ready for provisional acceptance in Chile in the second half of 2007. The first antenna to be supplied by the AEM Consortium is expected by the third quarter of 2008. Despite the delayed delivery of the AEM antennas, both suppliers are expected to deliver their 25th antenna by the end of 2011. Acceptance for the first antenna from Japan is expected to take place in December 2007. ronment impose severe requirements They are comprised of numerous elements The Preliminary Production Design Re- on these vehicles. Each transporter will (Figure 5), produced at different locations view for antennas to be produced by have a mass of about 150 tons, and in Europe, North America and Japan. Vertex RSI was held in September 2006, dimensions of about 10 × 15 × 6 m (width In the initial phase of construction ALMA the corresponding review for AEM an- × length × height). The contract for the decided, after the prototyping and de- tennas was held at the end of January production of these truly unique tranport- veloping stage, to build a set of eight pre- 2007. ers was signed by ESO with Scheuerle production units before moving to full pro- Fahrzeugfabrik GmbH (Germany) on duction. This initial phase started in the 22 December 2005. The first of the trans- years 2004 and 2005. Some components The ALMA Antenna Transporters porters will roll out of the hangar and will were successfully and completely pre- be tested in summer 2007 (see Figure 4) produced by the end of 2006 and the The antenna array at an altitude of to be transported and delivered to the rest are expected to be completed in the 5 000 m can be reconfigured by relocat- OSF in the fourth quarter of 2007. The course of 2007. ing antennas on the stations located on second vehicle is expected to be deliv- the Chajnantor plateau. The configura- ered about six months after the first one. The largest single element of the Front- tions can be changed from a compact End system is the cryostat, a vacuum one, in which all antennas operate within vessel with the cryo-cooler attached. The an area of 160 m × 250 m, to an extended The ALMA Front-End cryostats will house the receivers, which confi-guration for which the maximum are assembled in cartridges and can re- separation between antennas reaches The ALMA Front-End system is the first latively easily be installed or replaced. The about 15 km. In order to move antennas, element in a complex chain of signal re- corresponding warm optics, windows each with a mass of around 100 tons, the ception, conversion, processing and re- and IR filters were delivered by the Institut ALMA project has designed a special cording. The Front-End is designed to re- de Radio Astronomie Millimétrique (IRAM, transport vehicle (Wilson 2006). Two vehi- ceive signals in ten different frequency France). The operating temperature of the cles will be needed to cover the opera- bands (Table 1). In the initial phase of op- cryostats will be as low as 4 K. tional relocation requirements. These eration the antennas will be equipped transporters will move antennas between with six bands. These are Bands 3, 4, 6, ESO and the Rutherford Appleton Labo- the assembly and maintenance area at 7, 8 and 9. It is planned to equip the an- ratory (RAL, UK) launched a development the OSF and the AOS and at the AOS be- tennas with the missing bands at a later and pre-production programme for the tween different antenna stations for re- stage of ALMA operation. manufacture of eight completely opera- configuration of the array. By means of tional cryostats. Six cryostats (Figure 6) the transporter (Figure 4) the antennas The ALMA Front-Ends are superior to al- have been fully assembled. The remaining can be positioned to an accuracy of a most all existing systems. Indeed, devel- two units are in manufacture and the Cry- few millimetres on the high-precision sta- opment work for the ALMA prototypes ostats production contract was signed in tion interface. has also led to improved receivers for ex- April 2007. isting millimetre and sub-millimetre obser- The mass of the antennas, their high-pre- vatories. A development and pre-production cision and the hostile, high altitude envi- phase was also launched for the six dif-

The Messenger 128 – June 2007 27 Telescopes and Instrumentation Haupt C. and Rykaczewski H., Progress of the ALMA Project

Table 1: The ten frequency bands of ALMA.

ALMA Band Frequency Range (GHz) Receiver Noise Temperature (K) To be produced by1 Mixing scheme over 80 % of the RF Band at any RF Frequency 1 31.3–45.0 17 26 to be decided Single Side Band 2 67–90 30 47 to be decided Single Side Band 3 84–116 37 60 HIA Dual Side Bands 4 125–163 51 82 NAOJ Dual Side Bands 5 163–211 65 105 OSO (6 only) Dual Side Bands 6 211–275 83 136 NRAO Dual Side Bands 7 275–373 147 219 IRAM Dual Side Bands 8 385–500 196 292 NAOJ Dual Side Bands 9 602–720 175 261 NOVA Double Side Band 10 787–950 230 344 NAOJ (to be confirmed) Double Side Band ferent receiver cartridges (Table 1). The 1 IRAM Institut de Radio Astronomie Millimétrique NOVA Nederlandse Onderzoekschool voor technical specification of the various (Grenoble, France) Astronomie (Groningen, the Netherlands) HIA Herzberg Institute of Astrophysics (Victoria, NRAO National Radio Astronomy Observatory receiver cartridges are demanding, set Canada) (Charlottesville, USA) at the state of the art or even beyond NAOJ National Astronomical Observatory of OSO Onsala Space Observatory/Chalmers at the time of definition. The development Japan (Mitaka, Japan) Univeristy (Onsala, Sweden) programmes were successful, meeting essentially all of the requirements – and sometimes substantially exceeding them – specifically for the receiver noise temperatures. This is a very important achievement as to some extent the better FESS Tertiary Mirror Optics Tertiary Lens Optics Figure 5: Schematic noise performance and higher sensitivity (Bands 3 and 4) (Bands 1 and 2) of the ALMA Front-End System. partially compensate the loss in collecting area.

In the frame of the European FP6 pro- WVR gramme, ESO is leading a group of Euro- pean institutes to develop and build six Cryocooler Vacuum Vessel Band 5 receiver cartridges and to develop associated software. This project was approved by the European Commu- IF Switch Module Bulkhead IF Switch Control Module AMB Bus × 2 nity at the end of 2005. In parallel, NAOJ FEMC Module IF Outputs (4) Cryostat M&C Module DC Power in (#2) is leading activities related to the devel- DC Power in (#1) opment of Band 10 receivers. The Band 9 DC Power Districution Modules (10) Photonic Reference (Source) Photonic Reference (Return) cartridge was built by NOVA in the Neth- DC Supply M&C Module LO Offset LO Offset Reference Input erlands and is shown in Figure 7. The re- Distribution Module ceivers for Band 10 are still in an R&D phase; it is expected that in 2008 a final decision will be made on implement- ing this ALMA band with the highest frequency. Figure 6: ALMA Cryostat pre-production at RAL/UK. Pre-production of the cryogenic low-noise amplifiers for Band 7, 4–8 GHz, and for Band 9, 4–12 GHz, receivers has been successfully completed by Centro Astro- nómico de Yebes (CAY, Spain). Ampli- fier series production for Band 7 com- menced in February 2007 by Spanish industry.

Water Vapour Radiometers (WVRs) are needed to provide a correction of the phase fluctuations due to atmospheric water vapour fluctuations. The development of two prototype WVRs, at Cam-

28 The Messenger 128 – June 2007 Figure 8: Schematic of ALMA Signal Figure 7: ALMA Band 9 Processing and data transfer from Cartridges ready for the Front-End to the Correlator. Parts delivery, at NOVA in the to be provided by ESO are shaded in Netherlands. dark blue.

Antenna AOS Technical building

Photo- Front-End mixers Correlator

Tunable Filter IF Processing 8 × 2–4 GHz sub-bands

Digital De-Formatter Digitizer Digitizer 8 × 4 GHz –3 bit ADC 8 × 250 MHz, 48 bit cut Clock Optical De-MUX and Amplifier Data Encoder

Local Oscillator 12 × 10 GHz

Fibre Patch Panel From 175 stations 12 Optical Transmitters to 64 DTS Inputs 12 1 WDM Optical MUX

Optical Fibre bridge University (UK) and Onsala Space The European deliverables in the ALMA The ALMA Correlator Observatory (Sweden), was completed Back-End project are a number of com- and both underwent intensive testing at ponents, which are produced by several The ALMA Correlator, to be installed in the Sub-Millimeter Array (SMA) on Mauna European institutes, working closely with the AOS Technical Building, is the last Kea (Hawaii). The performance of both ESO, and NRAO. These deliverables are: component in the receiving end of the prototypes meets the requirements and digitizer chips and digitizer assembly; di- data transmission. It takes as input the demonstrated the atmospheric correction gitizer clock assembly; optical data trans- digitized signals from the individual an- method. The Call for Tender for the final mission system; fibre patch panel; optical tennas and outputs amplitude and phase detailed design and full WVR production multiplexers (MUX) and de-multiplexers on all of the interferometer baselines in was issued in February 2007 to indus- (De-MUX); Erbium-Doped Fibre Amplifiers each of a large number of spectral chan- try in ESO member states and production (EDFA), and photonic local oscillator pho- nels. It is a very large data-processing should commence in mid-2007. tomixers. system, composed of four quadrants, each of which can process data coming Development and pre-production of from up to 16 different antennas. The The ALMA Back-End these components has been successfully complete correlator will have 2912 print- completed; the components will be inte- ed circuit boards, 5200 interface cables, The ALMA Back-End systems deliver sig- grated at NRAO in Socorro and installed and more than 20 million solder joints. nals generated by Front-End units in- in the European and North American pro- The first quadrant was completed at stalled in each antenna to the Correlator totype antennas for tests at the ALMA NRAO in the third quarter of 2006. Work installed in the AOS Technical Building. Test Facility ATF. on the second quadrant is progressing Signal processing and data transfer is on schedule. schematically shown in Figure 8. In each An example of one of the various Back- of two orthogonal linear polarisations End components produced in Europe is Integral parts of the Correlator are Tuna- an intermediate frequency (IF) of 8 GHz the 4 GHz digitizer in its final layout (see ble Filter Bank (TFB) cards, which allow a bandwidth can be processed and re- Baudry et al. 2006, Figure 3). The clock major increase in the flexibility by sub- corded at any time. Analogue data, pro- rate is 4 GHz, allowing an input bandwidth dividing the frequency range into 32 inde- duced by the Front-End electronics, are of 2 GHz. The digitization uses three lev- pendently configurable sub-channels. processed and digitised before being for- els to preserve the signal-to-noise ratio. Four TFB cards are needed for the data matted for the transmission through the During the prototype and development coming from a single antenna. The TFB optical transmitter units and multiplexers. phase, the initial layout was optimised in cards have been developed and opti- All these elements are installed in the order to reduce the number of parts and mised by the University of Bordeaux over receiver cabins of each antenna. Optical the assembly costs. The final digitizers the last few years. Prototypes and pre- signals are then sent through optical fi- show an improved performance and production units were extensively tested bres to the AOS Technical Building. The a higher reliability. This work was carried and their performance was critically total distance in the most extended an- out in close collaboration between ESO reviewed in the first half of 2006. In the tenna configuration is about 15 km. At the and the University of Bordeaux. The first meantime, series production is pro- AOS Technical Building the incoming op- units have been shipped to Socorro gressing and the first batch of 108 out of tical signals are de-multiplexed and de- for final acceptance and integration with 560 TFB cards has been produced. formatted before entering the Correlator. tests at the ATF.

The Messenger 128 – June 2007 29 Telescopes and Instrumentation Haupt C. and Rykaczewski H., Progress of the ALMA Project

System Engineering and Integration delivery in the middle of 2007 for which Table 2: Software Development in European preparations are currently ongoing. Institutes. An important ALMA-wide activity is the System Engineering and Integration Software Activity Institute2 (SE&I) task, which covers coordination of Computing Science Software Requirements IRAM activities across the project. One of the Pipelining UKATC, MPIfR prime objectives of SE&I is to ensure that The development of a unified software Archiving Man. Un./JBO modules and equipment produced for an system for the ALMA Observatory is an- Observing Preparation UKATC ALMA subsystem, often in different loca- other important activity which requires Offline Data Processing MPIfR, CNRS tions of the world, fit physically and func- intensive interactions with all of the ALMA Telescope Calibration IRAM, IEM-CSIC tionally together. SE&I is also responsible engineering project teams. The nature ALMA Common Software OAT for the ALMA system design, technical of software development calls for a com- budgets and for ensuring the system inte- mon approach and policy from the very 2 IRAM Institut de Radio Astronomie Mil- grity, and hence has to ascertain that all beginning – not only with respect to the limétrique (Grenoble, France) UKATC United Kingdom Astronomy Technology interfaces between the various subsys- engineering teams, but also between the Centre (Edinburgh, United Kingdom) tems are completely understood, well de- European and North American partners. MPIfR Max-Planck-Institut für Radioastronomie fined, rigorously reviewed and properly In contrast to some cases of hardware (Bonn, Germany) documented. oriented activities, where specialised in- Man. Un. University of Manchester (Manchester, United Kingdom) struments are provided, this project re- JBO Jodrell Bank Observatory (Macclesfield, In order to achieve the tasks mentioned quires entire software packages to be de- United Kingdom) above, the SE&I team takes a central role veloped under a single management and CNRS Observatoire de Paris & Centre National in the preparation and management of organisation. de la Recherche Scientifique (Paris, France) project performance and engineering re- IEM-CSIC Instituto de Estructura de la Materia quirements and Interface Control Docu- ALMA Software Development is man- (Madrid, Spain) ments ICD. SE&I is also very active in aged as a truly integrated, trilateral orga- OAT Osservatorio Astronomico di Trieste organising, holding and chairing technical nisation. The European, North American reviews of the project, which could be and Japanese Executives have identified internal to ALMA or external, reviewing individual work packages under a com- the status and progress of the design mon leadership. and manufacturing of ALMA components by industry or scientific institutes. Product Work in Europe is organised through and Quality Assurance is another task ESO. The centre of European software and will receive a high visibility specifically development and management is at during the manufacturing phase. ESO’s headquarters in Garching. Many – Executive subsystem, which provides software packages are developed by the operator user interfaces; The SE&I group is also leading the activ- ESO in collaboration with European in- – Observatory Support Software, which ities related to Prototype System Integra- stitutes who have experienced and quali- provides the support tools needed by tion and the testing at the ALMA Test Fa- fied staff developing and testing the time allocation teams and the support cility (ATF) in Socorro (see front cover). required software. Table 2 gives an over- for data packages; During the years 2007 and 2008 the ATF view of software projects carried out by – Software engineering activity, which will serve as a facility where ALMA hard- various European institutes in association maintains the standards to be used in ware and software will be integrated into with ESO. hardware and software. an operational system using the two prototype antennas from Europe and North Major computing subsystems for which Figure 9 shows as an example the Opera- America. In a joint effort with the ALMA ESO has direct responsibility include: tor Master Console. This is part of the Science team, first fringes were recorded – ALMA Common Software (ACS), the Executive subsystem, for which ESO is in March 2007 (see ESO PR 10/07). The infrastructure used by all other soft- responsible. ATF is also used for training integration ware; and operations personnel for Chile and – Archive, both Front-End and science for qualifying equipment needed for ac- archive, collecting not only science Acknowledgements ceptance tasks in Chile, such as the Opti- data, but also any other information We would like to thank Claus Dierksmeier, Stefano cal Pointing Telescope and the Hologra- used by the ALMA observatory soft- Stanghellini, Gie Han Tan, Fabio Biancat Marchet phy System. ware; and Gianni Raffi for helping to prepare this article. – Integration and test activity, to get a Another major activity for the coming coherent and tested software system References years is the Assembly, Integration and out of the many subsystems; Verification (AIV) at the OSF. Equip- – High Level Architecture activity, respon- Baudry A. et al. 2006, The Messenger 125, 37 ment acceptance has already started and sible for the design of the ALMA soft- Wilson T. 2006, The Messenger 123, 19 AIV at the OSF will begin with the antenna ware and consistency of its interfaces; Haupt C. et al. 2006, Proc. SPIE 6271, 14

30 The Messenger 128 – June 2007 Figure 9: The ALMA Operator Master Console.

ALMA European Project Scientist Appointed

Tom Wilson (ESO) Leonardo’s main scientific interest is the study of circumstellar discs around newly formed stars. It is believed that many of The new ALMA European Project Scien- these discs of dust and gas will develop tist is Dr. Leonardo Testi. He took up the into planetary systems, so such studies appointment in May 2007. Leonardo Testi are complementary to the optical searches Photo: H. H. Heyer, ESO received his Ph.D. from the University for extrasolar planets being carried out, of Florence in 1997. Subsequently he was for example, with HARPS and the ESO a postdoctoral fellow at the Owens Valley 3.6-m telescope. The major drawbacks to Radio Observatory of Caltech. In 1998 present-day studies of circumstellar discs he joined staff of the Arcetri Astrophysi- are sensitivity and angular resolution. cal Observatory, and later on of INAF, for With ALMA, the sensitivity will be more which he also served on the Science than 40 times better, and the angular res- Council. Leonardo has been chair of the olution more than 5 times better, than European ALMA Science Advisory com- current instruments. Thus ALMA will allow mittee and a member of the ALMA breakthroughs in this area, as well as for Science Advisory committee, so he well studies of star formation, galaxy evolution knows the details of the project as well as and dynamics, Solar System science and the science that can be carried out with cosmology. Dr. Leonardo Testi ALMA.

The Messenger 128 – June 2007 31 Astronomical Science

FORS1 colour composite image of the H ii region NGC 2081 in the Large Magellanic Cloud taken with the new blue CCD. Three filter images isolating emission lines of [O ii], [O iii] and H-alpha were combined. Astronomical Science

Hunting for Frozen Super-Earths via Microlensing

Jean-Philippe Beaulieu1,3 8 Boyden Observatory, University of of cold telluric planets. Its detection Michael Albrow1,4 the Free State, Department of Physics, confirms the power of this method and, Dave Bennett1,5 Bloemfontein, South Africa given our detection efficiency, suggests Stéphane Brillant 1,6 9 Astronomisches Rechen-Institut (ARI), that these recently-detected planets John A. R. Caldwell1,7 Zentrum für Astronomie, Universität may be quite common around M stars, Johannes J. Calitz1,8 Heidelberg, Germany as confirmed by subsequent detection Arnaud Cassan1,9 10 Lawrence Livermore National Labora- of a ~ 13 Earth-mass planet. Using a Kem H. Cook1,10 tory, Livermore, California, USA network of dedicated 1–2-m-class tele- Christian Coutures1,3 11 University of Tasmania, School of scopes, we have entered a new phase Stefan Dieters 1,11 Mathematics and Physics, Hobart, of planet discovery, and will be able to Martin Dominik1,2,12,13 Tasmania, Australia provide constraints on the abundance Dijana Dominis-Prester1,14 12 Scottish Universities Physics Alliance, of frozen Super-Earths in the near future. Jadzia Donatowicz1,15 University of St Andrews, School of Pascal Fouqué1,16 Physics and Astronomy, St Andrews, John Greenhill1,11 United Kingdom The discovery of extrasolar planets is ar- Kym Hill1,11 13 Royal Society University Research guably the most exciting development Matie Hoffman1,8 Fellow in astrophysics during the past decade, Uffe G. Jørgensen1,17 14 University of Rijeka, Physics Depart- rivalled only by the discovery of the cos- Stephen Kane1,18 ment, Faculty of Arts and Sciences, mic acceleration. The unexpected variety Daniel Kubas1,6 Rijeka, Croatia of giant exoplanets, some very close Jean-Baptiste Marquette1,3 15 Technische Universität Wien, Austria to their stars, many with high orbital ec- Ralph Martin1,19 16 Observatoire Midi-Pyrénées, Labora- centricity, has sparked a new generation Pieter Meintjes1,8 toire d’Astrophysique, Université Paul of observers and theorists to address John Menzies1,20 Sabatier, Toulouse, France the question of how planets form in the Karen Pollard1,4 17 Niels Bohr Institutet, Astronomisk context of protostellar accretion discs. Kailash Sahu1,21 Observatorium, København, Denmark Planets are now known to migrate and Christian Vinter1,17 18 Department of Astronomy, University of maybe even be ejected, via planet-disc Joachim Wambsganss1,9 Florida, Gainesville, Florida, USA and planet-planet interactions. We are Andrew Williams1,19 19 Perth Observatory, Perth, Australia beginning to discover how our Solar Sys- Kristian Woller1,17 20 South African Astronomical Observa- tem fits into a broader community of Marta Zub1,9 tory planetary systems, many with very differ- Keith Horne1,2,12 21 Space Telescope Science Institute, ent properties. Microlensing-based Alasdair Allan 2,22 Baltimore, Maryland, USA searches play a critical role by probing for Mike Bode 2,23 22 eSTAR Project, School of Physics, cool planets with masses down to that Daniel M. Bramich1,2,24 University of Exeter, Devon, United of Earth. Of key interest is how planets Martin Burgdorf 2,23 Kingdom are distributed according to mass and or- Stephen Fraser 2,23 23 Astrophysics Research Institute, bital distance (Figure 1) as this information Chris Mottram 2,23 Liverpool John Moores University, provides a crucial test for theories of Nicholas Rattenbury 2,25 Birkenhead, United Kingdom planet formation. Core accretion models Colin Snodgrass 2,6 24 The Isaac Newton Group of Tele- (Ida and Lin, 2005) are today the best Iain Steele 2,23 scopes, Santa Cruz de La Palma, description for the formation of planetary Yiannis Tsapras 2,23 Canary Islands systems: the accretion of planetesimals 25 The University of Manchester, Jodrell leads to the formation of cores, which Bank Observatory, Macclesfield, then start to accrete gas from the primi- 1 PLANET Collaboration Cheshire, United Kingdom tive nebula. This scenario predicts that for 2 RoboNet Collaboration M dwarf stars there is a preferential for- 3 Institut d’Astrophysique de Paris, mation of Earth- to Neptune-mass planets CNRS, Université Pierre et Marie Curie, In order to obtain a census of planets in 1–10 AU orbits. These planets are ex- Paris, France with masses in the range of Earth to pected to form within a few million years. 4 University of Canterbury, Department Jupiter, eight telescopes are being used More massive planet (Jupiter) formation of Physics and Astronomy, by the combined microlensing cam- is hampered by a longer formation time Christchurch, New Zealand paign of the PLANET and RoboNet col- (10 Myr) during which the gas evaporates 5 University of Notre Dame, Department laborations for high-cadence photo- and is no longer available to be accreted. of Physics, Notre Dame, Indiana, USA metric round-the-clock follow-up of 6 ESO ongoing events, alerted by the OGLE There is a wide variety of planets and at 7 McDonald Observatory, Fort Davis, and MOA surveys. In 2005 we detected first sight it appears that our system Texas, USA a planet of 5.5 Earth masses at 2.6 AU is very special. However, our view of the

from its parent 0.22 MA M star. This whole picture is still blurred by obser- object is the first member of a new class vational biases inherent to the detection

The Messenger 128 – June 2007 33 Astronomical Science Beaulieu J.-P. et al., Hunting for Frozen Super-Earths via Microlensing

techniques using transits and radial ve- Known exoplanets: 11 + 180 + 4 = 195 (January 2007) locities. Both methods are more sensitive Orbit period in years (for Solar-mass star) to massive planets close to their parent 3 d 30 d 1yr 10 yr 100 yr star. Doppler measurements and the 4 Doppler: 180 space transit missions, such as COROT, 10 can already, or will shortly, be able to de- 1000 tect Neptune-mass planets close to their t, µFUN parent star. Direct detections fill the other J extreme of very large separations which 100 S are unknown in our Solar System. It is ET/RoboNe Kec therefore necessary to use different tech- k, VL N 10 TI U niques, each probing different areas of , HAT SIM the planet-mass versus orbital distance OGLE, TrES, WASP parameter space. 1 V E MPF OGLE, MOA, PLAN Planet mass in Earths Kepler Already with ground-based observations, 0.1 M the microlensing technique is sensitive M to cool planets with masses down to that 0.01 Transits: 11 (+ 3) Microlensing: 4 of the Earth orbiting 0.1–1 MA stars, the Astrometry: 0 most common stars of our Galaxy, in or- P bits of 1–10 AU. Currently, over 700 micro- 0.01 0.1 1 10 100 lensing events towards the Galactic Bulge Orbit radius in Astronomical Units (AU) are alerted in real time by the OGLE and MOA surveys each year. During these Figure 1 (above): Exoplanet discovery space (planet Figure 2 (below): The left panel shows the caustic events, a source star is temporarily mag- mass versus orbit size) showing the 8 planets from structure of a star/planet lens, with two possible tra- our Solar System (labelled as letters), 180 Doppler jectories of a source star. The right panel shows nified by the gravitational potential of wobble planets (black triangles), 11 transit planets the corresponding observed light curves. Hitting the an intervening lens star passing near the (blue circled crosses), and 4 microlensing planets planetary caustic, or passing close to it, induces a line of sight, with an impact parameter (red circled crosses). Also outlined are the regions short-lived but clearly detectable photometric signal. smaller than the Einstein ring radius RE, a that can be probed by different methods: Doppler, transits; astrometry; and microlensing from the quantity which depends on the mass of ground and space. Microlensing is a cost-efficient the lens, and the geometry of the align- way to measure the mass function of cool planets ment. For a source star in the Bulge, with down to the mass of the Earth. a 0.3 MA lens, RE ~ 2 AU, the projected angular Einstein ring radius is ~ 1 mas, and 0.10 Mass ratio q = 0.002 Impact angle = 271.0 (deg) Impact angle = 50.0 (deg) the time to transit RE is typically 20–30 Separation d = 1.2 days, but can be in the range 5–100 days. 17.5 0.05

A planet orbiting the lens star generates a Planetary caustic

E Central caustic 18.0 caustic structure in the source plane, with θ /

2 0.00 one small caustic around the centre of θ -Band magnitude mass of the system, the central caustic, I –0.05 and one or two larger caustics further 18.5 away, the planetary caustics. If the source star happens to reach the vicinity of one –0.10 of the caustics, its magnification is signifi- –0.10 –0.05 0.00 0.05 0.10 2520 2540 2560 2580 HJD - 2.450.000 cantly altered as compared to a single θ1/θE lens, resulting in a brief peak or dip in the observed light curve. the detection of planets in such events space to derive the planet/star mass ratio becomes highly efficient (Griest and q, and the projected separation d in units The duration of such planetary lensing Safizadeh 1998). In contrast, planetary of RE. In general, model distributions for anomalies scales with the square root of caustics are only approached for a spe- the spatial mass density of the Milky Way, the planet’s mass, lasting typically a cific range of orientations of the source the velocities of potential lens and source few hours (for an Earth) to 2–3 days (for a trajectory, but the characterisation of a stars, and a mass function of the lens Jupiter). These two caustics (Figure 2) planetary signal is much easier for such stars are required in order to derive prob- provide two modes for detection. When configurations. ability distributions for the masses of the the central caustic is approached for all planet and the lens star, their distance, as events with a small impact angle between The inverse problem, finding the prop- well as the orbital radius and period of source and lens star, corresponding to erties of the lensing system, is a complex the planet, by means of Bayesian analysis. a large peak magnification of the event, nonlinear one within a wide parameter

34 The Messenger 128 – June 2007 The observational challenge is to monitor In the case of OGLE, which has accumu- ongoing microlensing events, detected Liverpool Telescope 2.0-m lated many images of a given field before by the OGLE and MOA survey telescopes, a microlensing event is detected there, with a fleet of telescopes to achieve SAAO 1.0-m the template is built from a set of the best round-the-clock monitoring and detect Rockefeller 1.5-m images and is not held fixed throughout real-time deviations in the photometric the season. But in our case, we start ob- signal. The telescopes belonging to our serving an event when receiving the network together with their locations are Danish 1.5-m OGLE or MOA alert, so we have to build shown in Figure 3. During the coming the template ‘on the fly’. This generates three Galactic Bulge seasons (from May problems when new images appear after Perth 0.6-m to September 2007, 2008, 2009 in the Faulkes North 2.0-m a few nights, which are better than the southern hemisphere) we are planning to Canopus 1.0-m first template. We then have to re-run the use the eight telescopes of the PLANET/ process routine on all images of the event. RoboNET networks: Danish 1.5-m at A different image subtraction pipeline Faulkes South 2.0-m La Silla (Chile), Canopus 1.0-m at Hobart is used on the RoboNet telescopes, but it and Bickley 0.6-m at Perth (Australia), follows the same philosophy. Rockefeller 1.5-m at Bloemfontein and SAAO 1.0-m at Sutherland (South Africa). Figure 3: The different telescopes of The typical uncertainty of the on-line These are the standard telescopes of the the PLANET/RoboNet network. photometry is 1.2% for an I = 17.8 mag PLANET network, to which were added Galactic Bulge star at the Danish 1.5-m in 2004 two robotic telescopes of the instructing observers at the PLANET tele- telescope, and allows an on-line detec- UK RoboNet network, North Faulkes 2-m scopes by means of a web page. We tion of a deviating signal. When this ap- in Hawaii and Liverpool 2-m in Canary is- plan to embed our experience into future pears, excitement grows and an alert to lands, joined in 2006 by the South Faulkes advanced versions of the priority algo- homebase is issued. Homebase then 2-m in Australia. rithm and further automate this process. prompts an off-line reduction of the event images, which are regularly uploaded to At the beginning of the night, the observ- the Paris central archive. The off-line re- Observing strategy, and description of er finds on the PLANET web pages the duction is done with our other image sub- the reduction pipelines list of targets with sampling intervals set traction pipeline, pySIS, which facilitates up by the homebase. He then defines the ‘fine-tuning’, so as to get the best possi- A typical observing season of the Galac- exposure times for each target and re- ble photometry but is more difficult to tic Bulge starts at the beginning of May ports them on our private web page, so automate for real-time use. If the off-line every year and lasts four months. Among that the homebase can estimate the ob- reduction confirms the deviation, an alert the 691 alerts available in 2006 (579 from serving load at each telescope. Typical is issued to the microlensing community OGLE-III and 112 additional from MOA-II), sampling intervals are 0.5, 1, and 2 hours, to intensify observations and maximise about 180 are available every night in the according to the priority of each event. the chances of a good characterisation middle of the season. Of these, around However, in case of a high magnification of the deviation, which is absolutely nec- 20 targets can be monitored by 1-m-class event, when the sensitivity to a planet is essary for future modelling of the event. telescopes, whereas the Danish 1.54-m maximal, the sampling interval can be re- Moreover, all photometric data are made and the 2-m telescopes can follow more duced to a few minutes, to the exclusion public immediately, as assistance to events. Therefore, we must apply some of all other candidate objects. all teams in order to maximise the planet criteria to select our 20 targets for every hunting community’s success. observing night. This is done by one At the end of the exposure, the image is member of the collaboration acting as a pre-processed (bias, dark removed and coordinator, the so-called ‘homebase’. flatfielded), gets a standard name and The discovery of the frozen superEarth Depending upon the current magnifica- is passed to an on-line pipeline. Starting OGLE-2005-BLG-390Lb tion, the source brightness, and the in 2006, on all the PLANET telescopes, time of the last observation, a priority al- we shifted from a DoPhot-based on-line On 11 July 2005, the OGLE Early Warning gorithm assigns a worth to each of the pipeline to an image subtraction pipeline System announced the microlensing events and suggests sampling rates, with based on ISIS (Alard 2000). This robust event OGLE 2005-BLG-390, with a rela- the goal to maximise the planet detection implementation, named WISIS, has two tively bright G4III giant as the source star. efficiency. If the magnification of one main tasks: process takes all available PLANET/RoboNet included it in its list event becomes very high, it may become images of a given event, chooses the best of targets and started to monitor it on the sole designated target during that template and subtracts all images from 25 July. The microlens peaked at a mag- night. While these suggestions are direct- that template after convolving the refer- nification Amax = 3 on 31 July. We were ly submitted to intelligent agents steering ence point spread function (PSF) with the planning to continue to monitor it until the the robotic telescopes of the RoboNet kernel to mimic the current PSF. The source exited the Einstein ring, when on network, the homebase currently tunes update task only processes new images 10 August observers at the Danish tele- them using our experience gained, before using a previously chosen template. scope noticed a measurement deviating

The Messenger 128 – June 2007 35 Astronomical Science Beaulieu J.-P. et al., Hunting for Frozen Super-Earths via Microlensing

by 0.06 mag from the point source point lens prediction. They then took a second 33 1.6 measurement, deviating by 0.12 mag. OGLE OGLE data became available, confirming 1.5 the deviation seen in Chile. In order to 2 check the nature of the deviation, home- 2.5 1.4 base increased the proposed sampling Planetary 1 rate at the automated Perth telescope. 1.3 deviation Perth started to observe this event continuously as soon as the target was within 2 –1 0 9.5 10 10.5 11 reach. South Africa was clouded out, and when observations resumed in Chile, Magnification OGLE Danish it was clear that the anomaly was over. RoboNet Perth Different telescopes continued to ob- 1.5 Canopus MOA serve the microlensing event. Perth data – which were received only with some delay – finally confirmed the short-duration deviation with a good coverage of six 1 additional data points. Combined with –20 0 20 two additional independent data points Days since 31 July 2005 UT from the MOA team (Mt. John, New Zea- land), the evidence of a well-covered Figure 4: Light curve of OGLE-2005-BLG-390Lb, period of ~ 10 years (plotted as solid line). The best short-term deviation from a point-lens showing a brief planetary anomaly lasting for less alternative model is a binary source star but is re- than a day observed by four telescopes. The lens jected by the data. The dashed line is the point source light curve was on record (see Figure 4). star is a ~ 0.22 MA Galactic Bulge M dwarf orbited point lens model without the planetary deviation by a ~ 5.5 Earth-mass planet at ~ 2.6 AU with a (Beaulieu et al. 2006). Frenetic modelling activities started and it became clear very quickly that we had around the probed stars. The first at- tected by microlensing, two of which discovered a low-mass planet. The analy- tempts were done on individual high- are Jupiter analogues (Bond et al. 2004, sis has proven to be rather straightfor- magnification events using a point-source Udalski et al. 2005) and one Neptune ward for this event involving the transit of approximation, and then were applied (Gould et al. 2006), where the perturba- a large source star over a planetary caus- to a sample of the 42 well-covered micro- tion is due to the central caustic, and tic (Figure 5). The modelling of the photo- lensing events acquired by PLANET in one rocky/icy planet of 5.5 Earth mass metric data yields the mass ratio q = 7.6 1995–1999 (Gaudi et al. 2002). Less than named OGLE-2005-BLG-390Lb (Beau- ± 0.7 10–5, and the projected planet sepa- 1/3 of the lenses are orbited by Jupiters lieu et al., 2006) via a planetary caustic. ration d = 1.61 ± 0.008 (in units of RE, with orbits in the range 1–5 AU. We are They are overplotted on Figure 7. So the the Einstein ring radius). We performed a currently working on an analysis combin- era of discovery of frozen Super-Earths Bayesian analysis using Galactic mod- ing 11 years of data (1995–2005). We has been opened by the microlensing els and a mass function in order to derive calculate the detection efficiency of each technique. One of the consequences of probability distributions for the lens pa- microlensing light curve to lensing com- the discovery of such a small planet, is rameters (see Figure 2 from Beaulieu et panions as a function of the mass ratio that these small rock/ice planets should al. 2006) and a constraint on the nature and projected separation of the two com- be common. of the lens (low-mass main-sequence star ponents, now taking into account ex- or stellar remnant). The median values tended source effects. We use the same +0.21 yield a host star of mass 0.22 –0.11 MA lo- Bayesian analysis as for determining Obtaining more information about these cated at a distance of 6.6 ± 1.1 kpc within probability densities for the lens star and planets +5.5 the Galactic Bulge, orbited by a 5.5 –2.7 planet properties (Dominik 2006). Fig- Earth mass planet at an orbital separation ure 7 gives the mean detection efficiency Unlike other techniques, microlensing +1.5 of 2.6 –0.6 AU (Figure 6, and the artist of PLANET combining 14 well-sampled does not offer much chance to study the view of the planet by Herbert Zodet in events from 2004. For Jupiter-mass planetary system in more detail because ESO Press Release 02/06). planets, the detection efficiency reaches the phenomenon only occurs once for 50%, while it decreases only with the each star. Only a significant statistical square-root of the planet mass until the sample will allow us to reach firm conclu- Planet detection efficiency detection of planets is further suppressed sions and finally answer the question of by the finite size of the source stars for how special is our own Solar System. Ad- The detection efficiency of the experi- planets with a few Earth masses. Never- ditional information about a specific event ment can be determined from all collect- theless, the detection efficiency still re- can be obtained once the lens star is di- ed data, and comparison with the detec- mains a few per cent for planets below rectly detected. Here, we must wait many tions (or the absence of such) allows 10 Earth masses, made of rock and ice. years till the relative motion of the source conclusions about the planet abundance As of today, four planets have been de- and lens stars separate them on the sky.

36 The Messenger 128 – June 2007 Figure 6: Perturbation of the image of the source star by the planetary caustic observed with an ideal telescope. The time interval between the images is 0.1 day. The image scale is 30 microarcsec (Bennett and Williams).

0.10

0.05 E θ /

2 0.00 θ

–0.05

–0.10

0.90 0.95 1.00 1.05 1.10

θ1/θE

Figure 5: The source star and the planetary caustic of OGLE-2005-BLG6390. Notice the small size of the planetary caustic compared to the source star.

50 % 5 2 Bennett et al. (2006) using HST images 1000 have detected the lens star in the microlensing event OGLE-2003-BLG-235/ ) 25%

MOA-2003-BLG-53, and therefore the Earth 5 % uncertainty on the planetary parameters % have been greatly reduced. This could 100 5 be achieved too with HST or adaptive optics for OGLE-2005-BLG-169. In the case 2% of the lens OGLE-2005-BLG-390La, the Planet mass (M observation is much more difficult since 2 % we would need to detect a K ~ 22 mag 10 object at about 40 mas (in five years) from a star that is 10 mag brighter. In the coming years, statistics about frozen Super- 0.1 1.0 10.0 Earth planets orbiting M and K dwarfs will Semi-major axis (AU) be obtained, complementing the parameter space explored by space transit mis- is supported by the Agence Nationale de La Recher- Figure 7: Average detection efficiency of planets as a che. KHC work performed under auspices of US function of mass and orbital separation (assuming sions like COROT and KEPLER or ag- DOE, by UC, LLNL under contract, W 7405-Eng-48. circular orbits) in the 14 favourable events monitored gressive ground-based Doppler search, NJR acknowledges financial support by a PPARC by PLANET in 2004 (preliminary analysis) along like those using the CORALIE, SOPHIE PDRA fellowship and is partially supported by with the planets detected by microlensing as of 2006 and HARPS instruments. the European Community’s Sixth Framework Marie marked as points. Curie Research Training Network Programme, Con- tract No. MRTN-CT-2004-505183 ANGLES.

Acknowledgements References Relevant websites Microlensing follow-up observations would not hap- pen without the alert systems of the OGLE and MOA Alard C. 2000, A&AS 144, 363 PLANET: http://planet.iap.fr/ collaborations. We are very grateful to OGLE and Beaulieu J. P. et al. 2006, Nature 439, 437 RoboNet: http://www.astro.livjm.ac.uk/RoboNet/ MOA, and to the observatories that support our sci- Bennett D. P. et al. 2006, ApJ 647, 171 MicroFUN: http://www.astronomy.ohio-state. ence (ESO, Canopus, CTIO, Perth, SAAO, Boyden) Bond I. A. et al. 2005, ApJ 606, 155 edu/~microfun/ via the generous allocations of time that make this Dominik M. 2006, MNRAS 367, 669 MOA website: http://www.phys.canterbury.ac.nz/ work possible. The operation of Canopus Obser- Gaudi B. S. et al. 2002, ApJ 566, 463 moa/ vatory is in part supported by a financial contribution Gould A. et al. 2006, ApJ 644, L 37 OGLE website: http://www.astrouw.edu.pl/~ogle/ from David Warren, and the Danish telescope at Griest K. and Safizadeh N. 1998, ApJ 500, 37 La Silla is operated by IDA financed by SNF. The Ida S. and Lin D. N. C. 2005, ApJ 626, 1045 RoboNet project is funded by the UK STFC. HOLMES Udalski A. et al. 2005, ApJ 628, 109

The Messenger 128 – June 2007 37 Astronomical Science

Sulphur Abundances in Metal-Poor Stars – First Result from CRIRES Science Verification

Poul Erik Nissen1 by silicon burning in both Type Ia and connection, we note that the 869.5 nm Martin Asplund 2 Type II SNe. The point is that Type Ia SNe S i line is very weak in metal-poor halo Damian Fabbian 2 are not contributing with iron until the stars and hence the measured strength Florian Kerber 3 disc phase of our Galaxy, because their of the line may be affected by irregular Hans Ulrich Käufl 3 occurrence is delayed by about one fringing variations of the CCD detector Max Pettini 4 billion years relative to Type II SNe, due response, which are difficult to correct by to the lower progenitor mass of Type Ia flat-fielding. The stronger S i lines at 921.3 SNe. and 923.8 nm are less affected by such 1 Department of Physics and Astronomy, errors, but they occur in a spectral region Aarhus University, Denmark Sulphur is an element with an even num- hampered by numerous telluric lines that 2 Research School of Astronomy and ber of protons (Z = 16) like Mg and Si are often blended with the sulphur lines. Astrophysics, Australian National Uni- (Z = 12 and 14), and nucleosynthesis cal- versity culations predict that S is made in the 3 ESO same way as Mg and Si in Type II SNe. CRIRES observations 4 Institute of Astronomy, University of Hence, we expect [S/Fe] to have the Cambridge, United Kingdom same trend with [Fe/H] as [Mg/Fe] and CRIRES is a cryogenic, infrared echelle [Si/Fe]. Sulphur abundances derived from spectrograph designed to provide a re- the weak S i line at 869.5 nm by Israelian solving power l/∆l of up to 100 000 be- Sulphur is the tenth most abundant ele- and Rebolo (2001) and Takada-Hidai et tween about 950 nm and 5 000 nm as ment in the Universe and plays an im- al. (2002) showed, however, an increasing described in detail by Käufl et al. (2006). portant role in studies of the chemical trend of [S/Fe] towards low metallicities, The commissioning of this VLT instru- enrichment and star-formation history with [S/Fe] reportedly reaching values as ment opens up a new opportunity for in- of distant galaxies. Due to the lack of high as +0.8 dex (a factor of six higher dependent determinations of sulphur suitable sulphur lines in the visible part than the S/Fe ratio in the Sun) at [Fe/H] = abundances in metal-poor stars based of stellar spectra there is, however, still – 2.0. They suggested that such high on high-resolution observations of the no agreement on the abundance of sul- S/Fe ratios might be due to an enhanced S i triplet at 1.046 µm. As part of the sci- phur in Galactic metal-poor stars, and sulphur production in supernovae with ence verification of CRIRES, a spectrum we are therefore uncertain about the a very large explosion energy, so-called around the infrared triplet was obtained nucleosynthetic origin of sulphur. New hypernovae. Nissen et al. (2004), on the for the halo dwarf star G29-23 (V = 10.19, observations of infrared sulphur lines other hand, used the stronger S i lines [Fe/H] = –1.7) on 6 October 2006. The with the cryogenic high-resolution infra- at 921.3 and 923.8 nm to derive a near- entrance slit width of CRIRES was set at red echelle spectrograph (CRIRES) constant [S/Fe] ~ +0.3 for halo stars in 0.4 arcsec, which corresponds to a re- at ESO’s VLT are helping to solve this the metallicity range –3 < [Fe/H] < –1, as solving power of 50 000 with four detec- problem. expected if normal Type II SNe are the tor pixels per spectral resolution bin ∆l. sole source of sulphur. More recently, In order to improve the removal of sky Caffau et al. (2005) proposed a dichot- emission and detector dark current, the Abundance ratios of elements in celestial omy of [S/Fe] among Galactic halo stars observations were performed in nod- objects are usually given on a logarithmic with both high and low [S/Fe] values, ding mode with a shift of 10 arcsec be- scale with the corresponding solar ratio which would imply a very complicated tween the two settings of the star on the as the zero point. From the ratio between evolution of the sulphur abundance in our slit. The exposure time was 2400 s. The the number of iron and hydrogen atoms, Galaxy. seeing was rather poor (about 1.3 arcsec) we define the metallicity of a star as [Fe/H] but adaptive optics was applied to im-

≡ log(NFe/NH)Star – log(NFe/NH)Sun, and in A reason for the diverging [S/Fe] results prove the stellar image, and the com- order to get information on the nucleo- may be that errors in determining sul- bined spectrum has a very satisfactory synthesis of an element X, we are study- phur abundances are larger than claimed signal-to-noise ratio S/N ~ 330 per spec- ing how the quantity [X/Fe] ≡ log(NX/NFe)Star by the authors of the cited papers. In this tral dispersion pixel. This is considerably – log(NX/NFe)Sun varies as a function of [Fe/H]. For example, one finds that mag- 1.05 nesium has a constant overabundance [Mg/Fe] = +0.3 dex (corresponding to a 1.00 factor of two) in Galactic halo stars with metallicities in the range –4 < [Fe/H] < –1, 0.95 whereas [Mg/Fe] declines continuously to Figure 1: The CRIRES spectrum of the 0.90 zero in disc stars with –1 < [Fe/H] ≤ 0. A Relative flux metal-poor ([Fe/H] = –1.7) dwarf star similar trend is found for [Si/Fe]. This can G29-23 around the 1.046 µm S i triplet be explained if Mg and Si are made pri- 0.85 (dots) compared with synthetic model- marily by -capture reactions (i.e. suc- atmosphere line profiles for three a sulphur abundances corresponding to cessive captures of -particles) in Type II 0.80 a 1.0454 1.0455 1.0456 1.0457 1.0458 1.0459 1.0460 1.0461 [S/Fe] = 0.0, +0.3 and +0.6, respec- supernovae (SNe), whereas iron is made Wavelength (µm) tively.

38 The Messenger 128 – June 2007 better than our earlier UVES spectrum 1.05 Figure 2: The UVES spectrum of G29- of the same star (observed under similar 1.00 23 around the S i lines at 921.3, 923.8, and 869.5 nm (dots) compared with 0.95 conditions and with the same exposure synthetic line profiles for three sulphur time), which has S/N ~ 200 around the 0.90 abundances corresponding to [S/Fe] = S i lines at 921.3 and 923.8 nm. Further- 0.85 0.0, +0.3 and +0.6, respectively. more, unlike the UVES near-IR spectrum, Relative flux 0.80 the CRIRES spectrum at 1.046 µm is not 0.75 plagued by telluric lines and fringing resi- 0.70 duals. 9211.5 9212.0 9212.5 9213.0 9213.5 9214.0 9 214.5 1.04

The CRIRES spectrum of G29-23 is 1.00 shown in Figure 1 in comparison with 0.96 synthetic profiles of the sulphur lines for three values of [S/Fe]. Details of the 0.92

model-atmosphere calculations and Relative flux 0.88 the determination of the iron abundance, 0.84 which is based on Fe ii lines, can be found 0.80 in Nissen et al. (2007). As can be seen 9 236.0 9 236.5 9237.0 9237.5 9238.0 9 238.5 9 239.0 from the Figure, the synthetic profile cor- 1.02 responding to [S/Fe] = +0.3 provides 1.01 an excellent fit to the CRIRES data for all 1.00 three S i lines. 0.99 0.98 Relative flux Comparison with UVES observations 0.97 0.96 0.95 In Figure 2, the UVES spectrum of G29- 8693.0 8693.5 8694.0 8694.5 8695.0 8695.5 8 696.0 23 is shown for the sulphur lines at 869.5, Wavelength (Å) 921.3 and 923.8 nm. Telluric lines were removed by dividing by a scaled B-type star spectrum as described in Nissen et al. (2007). Again, the synthetic profile corresponding to [S/Fe] = +0.3 fits the data 0.8 Figure 3: [S/Fe] versus [Fe/H] for very well, but it is clear that the [S/Fe] val- Galactic stars. Disc stars ([Fe/H] > –1) 0.6 from Chen et al. (2002) are shown ue obtained from the weak 869.5 nm line with green crosses. For the halo stars is rather uncertain. 0.4 ([Fe/H] < –1), blue circles with error bars show data based on sulphur Although one should not put too much 0.2 abundances derived from the 921.3, 923.8 nm S i lines, and red circles

weight on a single star, the CRIRES spec- [S/Fe] (LTE) 0.0 show data from the weak 869.5 nm trum of G29-23 provides an important S i line. In the upper panel LTE has check of the sulphur abundances ob- –0.2 been assumed in deriving the S abun- tained from UVES spectra for 40 halo dances, whereas the lower panel –0.4 includes non-LTE corrections from stars by Nissen et al. (2007). As shown in –3.5 –3.0 –2.5 –2.0 –1.5 –1.0 –0.5 0.0 0.5 Takeda et al. (2005). the upper panel of Figure 3, the UVES data indicate that [S/Fe] lies around a pla- 0.8 teau of +0.3 dex if local thermodynamic 0.6 equilibrium (LTE, i.e. a Boltzmann distribution of the atoms over the possible atomic 0.4 energy states) is assumed when deriving the S abundances. If non-LTE corrections 0.2 based on the statistical equilibrium cal- 0.0 culations of Takeda et al. (2005) are tak- [S/Fe] (non-LTE) en into account, the plateau decreases to –0.2 about +0.2 dex as shown in the lower –0.4 panel of Figure 3. –3.5 –3.0 –2.5 –2.0 –1.5 –1.0 –0.5 0.0 0.5 [Fe/H] The scatter of [S/Fe] around this plateau is remarkably small, ±0.07 dex only, and no star has an enhanced S/Fe ratio

The Messenger 128 – June 2007 39 Astronomical Science Nissen P. E. et al., Sulphur Abundances in Metal-Poor Stars

([S/Fe] > +0.60) as claimed by Israelian there is an overall decrease in [S/Zn] at all cool halo giants may be particularly help- and Rebolo (2001), Takada-Hidai et al. but the highest values of [Zn/H] consid- ful in this connection. This line is formed (2002) and Caffau et al. (2005). Our re- ered here. Furthermore, non-LTE effects close to LTE in cool stars, because near- sults suggest that sulphur in the Galactic are most significant at low metallicities ly all sulphur atoms are in the lower ener- halo was made in the same way as with the result that, apparently, [S/Zn] re- gy level of the line (the ground state of Mg and Si, i.e. by a-capture processes in verts to solar values when [Zn/H] < –2. the S i atom), and the number of atoms in massive SNe. Such behaviour is unusual but, given our the upper level is determined by colli- current limited understanding of the nu- sions rather than radiative transitions. The cleosynthesis of Zn, cannot be excluded. forbidden line is very weak, but thanks The S/Zn ratio of Damped Lyman-alpha to the efficiency and high resolution of systems Taken at face value, the lack of a strong CRIRES, precision measurements will be metallicity trend in the lower panel of possible at metallicities as low as [Fe/H] ~ The sulphur abundances derived by Figure 4 would indicate that the useful- –2.5. Nissen et al. (2007) were combined with ness of the S/Zn ratio as a ‘clock’ of zinc abundances determined from the the star-formation history is rather limited. 472.2 and 481.1 nm Zn i lines. Both S and The question that remains concerns References Zn are among the few elements which the accuracy of the non-LTE calculations Asplund M. 2005, ARA&A 43, 481 are not readily depleted onto dust in the by Takeda et al. (2005); they depend Caffau E. et al. 2005, A&A 441, 533 interstellar medium. For this reason, critically on the rather uncertain cross- Chen Y. Q. et al. 2002, A&A 390, 225 they are key to studies of metal enrich- section for inelastic collisions with neutral Israelian G. and Rebolo R. 2001, ApJ 557, L43 ment in distant galaxies, particularly hydrogen atoms, which tend to enforce Käufl et al. 2006, The Messenger 126, 32 Nissen P. E. et al. 2004, A&A 415, 993 those detected as damped Lyman-alpha an LTE population of the energy levels Nissen P. E. et al. 2007, A&A 469, 319 systems (DLAs) in the spectra of high- (Asplund 2005). Future observations of Takada-Hidai M. et al. 2002, ApJ 573, 614 redshift quasars. Assuming that sulphur the forbidden sulphur line at 1.082 µm in Takeda Y. et al. 2005, PASJ 57, 751 behaves like other a-capture elements and that Zn follows Fe, the S/Zn ratio has been used to estimate the timescale of the star-formation process in DLAs. In particular, it has been argued that a solar S/Zn ratio indicates that Type Ia SNe have contributed to the chemical enrichment and that the age of a DLA system with a solar-like S/Zn therefore must be at 0.6 Figure 4: [S/Zn] versus [Zn/H] for Gal- least one billion years. actic stars and damped Lyman-alpha 0.4 systems. Typical 1-s error bars are shown. In the upper panel the stellar 0.2 Before such a conclusion can be made, S and Zn abundances have been de- it is important to clarify the trend of [S/Zn] 0.0 rived assuming LTE, whereas the among Galactic stars. Figure 4 shows lower panel includes non-LTE correc- [S/Zn] –0.2 tions from Takeda et al. (2005). the results from Nissen et al. (2007). It is found that the trend of [S/Zn] depends –0.4 quite critically on whether LTE is as- Stars LTE DLAs –0.6 sumed or not. When the non-LTE correc- –0.8 tions of Takeda et al. (2005) are applied, –2.8 –2.4 –2.0 –1.6 –1.2 –0.8 –0.4 0.0 0.4

0.6

0.4

0.2

0.0

[S/Zn] –0.2

–0.4 Stars, non-LTE DLAs –0.6

–0.8 –2.8 –2.4 –2.0 –1.6 –1.2 –0.8 –0.4 0.0 0.4 [Zn/H]

40 The Messenger 128 – June 2007 Astronomical Science

Using Globular Clusters to Test Gravity in the Weak Acceleration Regime

Riccardo Scarpa1 be facing a breakdown of Newton’s law, velocity dispersion profile mimics what is Gianni Marconi 2 rather than the effects of dark matter. observed in high surface brightness Roberto Gilmozzi 2 elliptical galaxies. That is, the dispersion Giovanni Carraro 3 Since globular clusters are free falling to- is maximal at the centre, then decreases ward the Milky Way, their internal dy- toward a constant value at large radii,

namics are only affected by tidal stress, where the acceleration goes below a0. 1 Instituto de Astrofísica de Canarias, which is in most cases well below a0. With data for five globular clusters, one La Laguna, Tenerife, Spain Therefore the internal dynamics of globu- can start comparing results and, interest- 2 ESO lar clusters can be used to probe the ingly, we found that in all cases the flat- 3 Università di Padova, Italy same range of accelerations typical of tening of the dispersion profile occurs for galaxies, without the complication of dark very similar values of the internal acceler- matter. Following this idea, we have ation of gravity. Values are collected in We report on the results from an on- studied the dynamics of the external re- Table 1, where we present, for each clus- going programme aimed at testing gions of w Centauri (Scarpa, Marconi ter, its absolute V magnitude, the radius Newton’s law of gravity in the low ac- and Gilmozzi 2003). This massive cluster where the flattening occurs, and the cor- celeration regime using globular clus- was selected because proper motions responding acceleration derived assum- ters. We find that all clusters studied so for several thousand stars were available ing a mass-to-light ratio of one. Within er- far behave like galaxies, that is, their in the literature. Combining proper mo- rors all profiles flatten out at a0. It is worth velocity dispersion profiles flatten out at tions with radial velocity information al- pointing out that these five clusters are large radii where the acceleration of lows all three components of the velocity different in size, mass, position in the halo gravity goes below 10–8 cm s–2, instead vector to be obtained, thus fully address- of the Milky Way and dynamical history. of following the expected Keplerian ing the possible effects of anisotropy. The Therefore there is no obvious reason why fall-off. In galaxies this behaviour is as- result is clearly shown by Figure 1. The they should conspire to have a similar cribed to the existence of a dark-matter velocity dispersion profiles, as derived for velocity dispersion profile at large radii. halo. Globular clusters, however, are the three components of motion, are very not supposed to contain dark matter, similar, showing that the cluster is iso- Galaxies provide us with another pow- hence this result might indicate that our tropic (as is also indicated, by the way, erful tool to further disentangle non- present understanding of gravity in the from its very nearly circular shape). More- Newtonian effects from other more weak regime of accelerations is incom- over, the dispersion is found to be con- classical phenomena like tidal heating, or plete and possibly incorrect. stant at large radii. a combination of effects like the distribution of dark remnants plus tidal heat- Following this initial result, that could be ing plus cluster evaporation and so on, Newtonian dynamics and globular due to some other effect like tidal that might be responsible for increasing clusters heating, we collected data for three more the velocity dispersion in the outskirts. globular clusters: NGC 7078 (M15) High surface brightness galaxies (HSB) Stars within galaxies, and galaxies within and NGC 6171 (Scarpa, Marconi, and and low surface brightness galaxies clusters of galaxies, are very far apart Gilmozzi 2004A,B), and NGC 7099 (LSB) are known to behave differently. from each other. As a consequence, the (Scarpa et al. 2006). Data for a fourth The latter have a remarkably flat velocity typical accelerations governing the cluster, NGC 6341 (M92), appeared dispersion profile (e.g., Mateo 1997; dynamics of galaxies are orders of mag- recently in the literature (Drukier et al. Wilkinson 2006), allegedly due to LSB nitude smaller than the ones probed 2006) and this cluster is also presented galaxies being dark matter dominated all in our earth-based laboratories or in the here. In all cases (see Figure 2) the the way to their centre, while HSB galax- Solar System. Thus, any time Newton’s law is applied to galaxies (e.g., to infer 30 the existence of dark matter), its validity is ω Cen severely extrapolated. Although there are in principle no reasons to distrust

Newton’s law in the weak acceleration 20 regime, agreement has been reached (e.g., Binney 2004) that galaxies start to deviate from Newtonian dynamics, and that dark matter is needed to reconcile Figure 1: The velocity dispersion profile of w Cen- observations with predictions, always for 10 tauri. Circles and squares represent the disper-

the same value of the internal accelera- Velocity dispersion (km/s) sion as derived from proper motion data. Crosses tion of gravity of a ~ 10–8 cm s–2. This are radial velocity dispersions from the literature, to 0 which we added data for 75 stars (the four last systematic property, more than anything points with error bars). The solid line is not a fit to the else, raises the possibility that we may 0 data. It is a Gaussian plus a constant drawn to 0 10 20 30 40 50 emphasise the flattening of the dispersion at large Distance from cluster centre (pc) radii.

The Messenger 128 – June 2007 41 Astronomical Science Scarpa R. et al., Using GCs to Test Gravity in the Weak Acceleration Regime

12 Figure 2: Velocity dispersion profiles of the other four clusters studied so far. In all cases the velocity dis- 5 NGC 7078 NGC 6171 persion is maximal at the centre, then decreases to 10 converge toward a constant value at large radii. This is similar to the case of high surface brightness 4 elliptical galaxies. Note that the profiles of NGC 6171 8 and NGC 7099 were derived from our own data, while the profiles of NGC 7078 and NGC 6341 were 3 derived from data in the literature (Drukier et al. 2006 6 and references therein). The solid line has the same meaning as in Figure 1. 2 4 Velocity dispersion (km/s) Velocity dispersion (km/s) 2 1

0 0 0 10 20 30 40 50 0 5 10 15 20 Distance from cluster centre (pc) Distance from cluster centre (pc)

figuration three 2700 s exposures were NGC 7099 8 NGC 6341 obtained under good atmospheric condi- 6 tion (clear sky and seeing ~ 1 arcsec) on 29 and 30 August 2005. 6 Radial velocities were derived by cross- 4 correlating the spectra of each target with 4 a template (the target with the best spectrum). The two configurations shared a 2 small number of stars, to evaluate and Velocity dispersion (km/s) Velocity dispersion (km/s) 2 eliminate possible offsets in the velocity zero point. A posteriori, we verified that no correction was necessary down to a –1 0 0 level of accuracy of 250 m s , well below 0 5 10 15 20 0 5 10 15 20 the accuracy required for our study. Fi- Distance from cluster centre (pc) Distance from cluster centre (pc) nally, keeping in mind that we are interested only in the velocity dispersion, the ies are baryon-dominated at the centre. to the turn off, between 15 and 18 appar- global velocity zero point was derived In view of what we have found for dense ent V mag. Observations were then ob- by identifying a few lines in the spectrum globular clusters that probe the same tained with FLAMES at the ESO VLT tele- of the template. Altogether 126 radial ve- accelerations as HSB galaxies, it is natu- scope. FLAMES is a fibre multi-object locities with accuracy better than 1 km s–1 ral to wonder whether low-concentration spectrograph, allowing the simultaneous were derived. Of these, all but two were globular clusters behave like LSB gal- observation of up to 130 objects. We se- found to be cluster members, consistent axies. That is, do low-concentration glob- lected the HR9B set-up that includes with the very low contamination expected ular clusters have constant velocity dis- the magnesium triplet covering the wave- at the high Galactic latitude (b = –89 de- persion? length range 5143 < l < 5346 Å at res- grees) of this cluster. olution R = 25900. Stellar astrometry was derived cross correlating the stellar posi- To better constrain the velocity disper- The case of NGC 288 tions on the EIS frames with coordinates sion close to the cluster centre, we com- from the US Naval Observatory (USNO) bined our data with data for 24 additional In an attempt to answer this question we catalogue, which proved to have the re- stars, mostly within 6 pc from the clus- studied NGC 288, a low-concentration quired accuracy (0.3 arcsec) for FLAMES ter centre, and radial velocity accuracy cluster located at 8.3 kpc from the Sun observations. Two different fibre configu- better that 1 km/s (from Pryor et al. 1991). and 11.6 kpc from the Galactic Centre, rations were necessary to observe all the After applying an offset of 2.9 km/s to that has internal acceleration of gravity selected stars (Figure 3). For each con- match our radial velocity zero point, these everywhere below a0, as is the case for –2 LSB galaxies. The initial selection of Cluster Name Mv R (pc) a (cm s ) Table 1: For each globular cluster targets around NGC 288 was based on NGC 5139 (w Centauri) –10.29 27 ± 3 2.1 ± 0.5 × 10–8 studied, the absolute magnitude, radius at which the velocity dispersion NGC 6171 (M107) –7.13 8 ± 2 1.3 ± 0.6 × 10–8 colour, as derived from the analysis of flattens and the corresponding ac- –8 ESO Imaging Survey frames. A catalogue NGC 6341 (M92) –8.20 12 ± 2 1.5 ± 0.6 × 10 celeration due to gravity for a mass-to- of targets was prepared including mostly NGC 7078 (M15) –9.17 20 ± 2 1.4 ± 0.4 × 10–8 light ratio of 1, are listed. stars from the sub-giant branch down NGC 7099 (M30) –7.43 10 ± 2 1.1 ± 0.4 × 10–8

42 The Messenger 128 – June 2007 –35 Figure 4: The velocity dispersion profile of the low-concentration cluster NGC 288 4 NGC 288 NGC 288. From the point of view of the internal acceleration of gravity, this –40 cluster is the equivalent of a low surface brightness galaxy and, similarly to 3 what is found in these galaxies, the –45 dispersion profile is remarkably flat.

Radial velocity (km/s) –50

0 5 10 15 20 Velocity dispersion (km/s)1 Distance from cluster centre (pc)

Figure 3: Radial velocity distribution for the low- concentration cluster NGC 288. The 124 stars stud- 0 ied as part of this work are shown as solid circles, 0 5 10 15 20 while 24 velocities from Pryor et al. 1991 are shown Distance from cluster centre (pc) as open squares. The data distributes uniformly from the centre to 20 pc, showing no indication of a decrease of the dispersion. Bin limits (pc) Stars/bin bin centre (pc) s (km s–1) Table 2: Data on the binned radial 0–2 8 1.34 2.32 ± 0.64 velocity dispersion for NGC 288. data smoothly merge with ours in the re- 2–4 21 3.21 2.41 ± 0.41 gion of overlap, showing basically the 4–6 20 5.09 2.73 ± 0.46 same velocity dispersion (Figure 3). This 6–8 22 7.18 2.52 ± 0.41 combined sample was used to search 8–10 20 9.02 2.60 ± 0.45 for ordered rotation in NGC 288 that might 10–12 14 10.71 2.16 ± 0.46 contribute to sustain the cluster, finding 12–14 25 12.95 1.90 ± 0.31 no evidence for rotation down to the level 14–20 17 16.12 2.17 ± 0.42 of 0.5 km/s.

Velocities from this combined data set al- erty of being rather diffuse, with a central known as MOND (Milgrom 1983) to de- lowed us to build a well-sampled velocity surface brightness of ~ 20 mag arcsec–2 scribe successfully the properties of a dispersion profile from the centre to al- in the V band. This has the important large number of stellar systems without most 18 pc (Figure 4). In Table 2 we re- consequence that the internal accelera- invoking the existence of non-baryonic port the velocity dispersion in km/s with tion of gravity is extremely small. Indeed dark matter, we see here evidence for a 1s uncertainties, together with the limits it can be shown to be everywhere be- failure of Newtonian Dynamics for ac- of the bins, the number of stars in each low a0 for any of the typical mass-to-light celerations below a0. Given the potential bin, and the bin centre, defined as the ratios assumed for globular clusters. impact of this claim, we urge the astro- mean of the radii of the stars in the bin. nomical community to disprove or gen- It is well known that LSB galaxies have eralise our results. Looking at both Figures 3 and 4, we see velocity dispersion profiles which are no indications of a vanishing velocity dis- remarkably flat, with no central maximum persion at large radii, rather, the disper- (Mateo 1997; Wilkinson et al. 2006). References sion remains constant with an average If this property is due to a breakdown of Binney J. 2004, in “Dark Matter in Galaxies”, value of 2.3 ± 0.15 km/s over the full range Newtonian dynamics below a0 (and ed. S. D. Ryder et al., IAUS 220, 3 of radii covered by the data. not because of dark matter), then the ve- Drukier G. A. et al. 2007, AJ 133, 1041 locity dispersion of NGC 288 should Mateo M. 1997, in “The nature of Elliptical Galaxies”, The five clusters cen, NGC 7078, mimic what is observed in these galaxies. ed. M. Arnaboldi, ASPC 116, 259 w Milgrom M. 1983, ApJ 270, 365 NGC 6171, NGC 7099, and NGC 6341, Within the errors, this is certainly the case Pryor C. et al. 1991, AJ 102, 1026 while having different sizes, different (Figure 4). The similarity between NGC Scarpa R., Marconi G. and Gilmozzi R. 2003, masses, and different dynamical histo- 288 and LSB galaxies is striking. The ca- A&AL 405, 15 ries, have the common property of being nonical explanation for the constant Scarpa R., Marconi G. and Gilmozzi R. 2004a, IAUS 220E, 215 highly concentrated, thus the acceler- velocity dispersion in LSB galaxies is that Scarpa R., Marconi G. and Gilmozzi R. 2004b, in ation of gravity in their central regions is these objects are dark matter domi- “Baryons in Dark Matter Halos”, eds. R. Dettmar et al., SISSA, Proceedings of Science, 55.1, above a0. Only in the outskirts is the nated all the way to their centres. In the acceleration below this value. All these case of a globular cluster, this expla- http://pos.sissa.it Scarpa R. et al. 2007, A&AL 462, 9 clusters are found to behave like HSB nation is quite unpalatable. Thus, in view Wilkinson M. I. et al. 2006, The Messenger 124, 25 elliptical galaxies, i.e. to have a constant of these results for globular clusters and velocity dispersion at large radii. By also of the amazing ability of a particular contrast, NGC 288 has the peculiar prop- modification of the Newtonian Dynamics

The Messenger 128 – June 2007 43 Astronomical Science

Dissecting the Nuclear Environment of Mrk 609 with SINFONI – the Starburst-AGN Connection

Jens Zuther1 result from galaxy interactions. For Ultra ite nature. Their soft X-ray spectra are Sebastian Fischer1 Luminous Infra-red Galaxies (ULIRGs), flat, but it is still not clear how this strong Jörg-Uwe Pott1,2 which show the most extreme cases of and hard X-ray emission can be recon- Thomas Bertram1 infrared nuclear activity, there is intriguing ciled with the weak optical Seyfert char- Andreas Eckart1 evidence for a connection between acteristics. The faintness of these objects Christian Straubmeier1 galaxy interaction and nuclear activity. in the X-ray, as well as in the optical Christof Iserlohe1 domain, has prevented them from being Wolfgang Voges 3 Internal triggers are based on instabil- studied in detail so far. Günther Hasinger 3 ities generated from within the host. For example a two-step process has been proposed that is able to sweep the inter- The SINFONI observations 1 I. Physikalisches Institut, Universität zu stellar medium (ISM), via a stellar bar, Köln, Germany from large scales into a disk of several Near-infrared imaging spectroscopy (cf. 2 ESO hundred pc in radius. In the second step, Gillessen et al. 2006) has considerable 3 Max-Planck-Institut für Extraterres- further instabilities (bar-within-bar) drive advantages over visible wavelength spec- trische Physik, Garching, Germany the material close to the nucleus, until troscopy. Besides the much smaller dust viscous processes take over the angular extinction, there are a number of NIR momentum transport. diagnostic lines that probe the stellar and The new VLT instrument SINFONI non-stellar content in Mrk 609. Among gives us a view onto the circumnuclear While in quiescent galaxies, extensive these are hydrogen recombination lines, properties of AGN in unprecedented star formation appears to be related ro-vibrational transitions of H2, stellar fea- detail, even beyond our local Universe. to large-scale bars, the observational evi- tures like the CO(2–0) and CO(6–3) ab- As a science verification target, the dence for non-axisymmetry-related sorption band heads, as well as forbid- showcase object Mrk 609 demonstrates nuclear activity is not as clear for Seyfert den lines like [Fe ii] and [Si vi]. impressively the necessity of adaptive galaxies. A slight but significant increase optics assisted integral-field spectros- in the galactic-bar fraction of active gal- The data (Zuther et al. 2007) have been copy in order to distinguish between axies has been found when compared to acquired during the science verification Seyfert and starburst characteristics on non-active galaxies. This does not appear phase of SINFONI in August/October nuclear scales. to be the case for nuclear bars. Further- 2004. For the first time we have spatially more, there are a considerable number of resolved the circumnuclear environment AGN that show no signs of the presence on the scale of 270 pc in the J and H + K Fuelling of nuclear activity of a bar, as well as of non-active galaxies bands (Figure 1). The morphology is com- that do possess bars. plex, and the continuum image reveals The presence of the Seyfert phenomenon a stellar bar-like structure superposed on is supposed to originate in the accre- the point-like Seyfert nucleus (Figure 1a). tion of matter onto a super-massive black Mrk 609: a starburst/Seyfert composite The distribution of hydrogen recombina- hole (SMBH) in the centre of a galaxy. galaxy tion emission (Paa) is clumpy and peaks Nuclear activity is composed of nuclear at the tip where the potential bar meets starbursts and Seyfert-like emission. Mrk 609 is classified as a starburst/ the spiral arms and in regions along the The fuel necessary for driving this activity Seyfert composite galaxy. This class of minor axis (Figure 1b). The presence of has to be transported from galactic AGN appears to be best suited to study nuclear broad Paa and [Si vi] are clear in- scales (~ 10 kpc) down to nuclear scales the starburst-AGN connection, since dicators of the accretion of matter onto of ~ 10 pc. We are still far from under- the AGN and starburst components pre- a nuclear supermassive black hole. The standing the detailed processes that cre- sent themselves at the same level of distribution of molecular hydrogen follows ate non-axisymmetric potentials leading activity (Moran et al. 1996). Composite the continuum shape, while that of [Fe ii] to the dissipation of angular momen- galaxies can be characterised by optical is aligned with the minor axis of the tum. Such instabilities are needed for the spectra which are dominated by star- continuum and with the H-recombination gas and stars to fall towards the nuclear burst features, while the X-ray luminosity emission (Figure 1c and 1d). region. However, considerable theoretical and its variability are typical for Seyfert as well as observational effort has been galaxies. The former property is based on The well established BPT emission line made to understand these processes the emission-line diagnostic diagrams diagnostics at visual wavelengths fail (e.g. Shlosman et al. 1990; Knapen 2005). by Baldwin, Phillips and Terlevich (BPT for regions with considerable extinction. We can distinguish external and internal 1981). Close inspection of the optical Recently it was found that an analogous triggers of the fuelling process: spectra often reveals some weak Seyfert- NIR line diagnostic diagram, using [Fe ii]/

like features, e.g. [O iii] being significant- Pab and H2/Brγ line ratios, allows us to External triggers are related to the envi- ly broader than all other narrow lines, or a distinguish between starbursts (photoion- ronment of galaxies and gravitational weak broad Ha component. There is a isation excitation), AGN (mixed excitation), interaction. Non-axisymmetry, which can resemblance to narrow-line X-ray galax- and LINERs (shock excitation). In this dia- lead to loss of angular momentum, can ies, which also show spectra of compos- gram, the nucleus of Mrk 609 shows

44 The Messenger 128 – June 2007 signs of LINER activity (Figure 2). Shock- driven excitation can be recognised by its high [Fe ii]/Pab and H2/Brγ values. Our integral-field data clearly resolve the nuclear and starburst activity in the central kiloparsec. Extinction appears to play 3� × 3� no crucial role in this region, since the H-recombination line ratios are consistent K Paα with unreddened case-B values. This is furthermore supported by the strong Lya emission in the ultraviolet.

The different regions characterised by clumpy Paa emission (Figure 1b) clearly follow a trend from a LINER-like value N at the nucleus to a starburst-like value in the most distant North-eastern region (data point 5 in Figure 2). The circumnu- [Fe II] E clear regions (data points 2, 3, and 4) fall in the domain of mixed excitation. In con- Figure 1: Hubble Space Telescope (HST) F606W- trast to our nuclear classification, the line band image of Mrk 609 (centre, from Malkan et al. 1998) overlayed with SINFONI maps of various ratios extracted from the total field of spectral features: (a) K-band continuum map, (b) Paa view resemble those of a typical Seyfert map, (c) [Fe ii] 1.275 µm, and (d) 1-0 S(1) molecular galaxy. The same Seyfert characteris- hydrogen. The SINFONI field of view is indicated by tics are obtained from the large aperture the white box in the HST image. Sloan Digital Sky Survey visual spectrum. This demonstrates how the choice of spatial scales to be studied can influence the resulting classification. Our LINER classification of Mrk 609, together with Shock 1.0 published data on variability of its non- stellar NIR emission, might be explained 5 with the duty-cycle hypothesis, in which 0.5

short-lived accretion events occur period- ) ically and lead to the appearance of β 1 ]/Pa

Seyfert features in the high state and low- II 0.0 2 total ionisation (shock-driven) emission fea- LINER tures in the low state. In order to ver- log ([Fe 4 ify this possible scenario, multi-epoch –0.5 SINFONI observations are needed. 3 AGN

The small spatial scales which SINFONI SB –1.0 resolves on Mrk 609 allow for an investi- Photoionisation gation of the transport of matter within the central one kiloparsec. Obviously, –1.0 –0.5 0.0 0.5 1.0 1.5 log (H /Brγ) Mrk 609 shows no signs of external trig- 2 gers (i.e. interaction with companion galaxies). The presence of a nuclear bar- Figure 2: Line ratios of [Fe ii] 1.257 µm/Pab and Starbursts like stellar structure, as well as the 1‑0 S(1) 2.121 µm/Brg. Activity types (starburst (SB), Seyfert 1 AGN and LINER) are indicated. Filled symbols re- Seyfert 2 clumpy morphology of the emission line present our SINFONI measurements of five distinct LINER gas, fits into the picture of internal trig- regions of Mrk 609, as well as of the total field-of- Supernova gers, feeding the AGN and circumnucle- view (red star). On account of missing J-band data, region 5 is only accurately located along H /Br . ar star formation. However the chicken- 2 g Open symbols correspond to literature values; and-egg problem – whether the star orange diamonds represent starburst galaxies; red for-mation activates the accretion onto left triangles Seyfert 1 galaxies; magenta headlong the SMBH or AGN feed-back initiates triangles Seyfert 2s; blue circles LINERs; and grey nearby starburst activity – remains open. asterisks supernovae. The diagram is interpreted as displaying the transition from pure photoionisation (lower left corner) to pure shock driven emission (upper right).

The Messenger 128 – June 2007 45 Astronomical Science

Outlook backyard of our Milky Way towards larger References look-back times and stronger nuclear Baldwin J. A., Phillips M. M. and Terlevich R. 1981, The starburst/Seyfert composite nature activity, allows for a comparison with PASP 93, 5 of Mrk 609 can be disentangled into dis- local AGN on the same physical scales. Gillessen S. et al. 2006, The Messenger 120, 26 tinct regions of star formation and strong Then we are able to study scenarios such Knapen J. H. 2005, Ap&SS 295, 85 nuclear activity. Probably, this is true as whether circumnuclear starburst Malkan M. A. et al. 1998, ApJS 117, 25 Moran E. C. et al. 1996, ApJS 106, 341 for most composite galaxies. Whether features generally accompany the cores Rodríguez-Ardila A. et al. 2005, MNRAS 364, 1041 relationships between the occurrence of of galaxies with even stronger nuclear ac- Shlosman I., Begelman M. C. and Frank J. 1990, dynamical instabilities, star formation, tivity, i.e. pure Seyferts and/or QSOs, or Nature 345, 679 and AGN activity are causally linked can if enhanced star formation is a distinct Lípari S. L. and Terlevich R. J. 2006, MNRAS 368, 1001 only be determined with AO-assisted phase in the evolution of AGN (e.g. Lípari Zuther J. et al. 2007, A&A 466, 451 imaging spectroscopy (e.g. SINFONI) ob- and Terlevich 2006). However, resolving servations on a larger sample of this the central region of these objects on class of objects. Moving beyond the the 100 pc scale is fundamental for these studies.

1�

Gas Stars E

The famous luminous infra red galaxy merger Arp 220 is shown here in more results from VLT SINFONI, this time used in tandem with the Laser Guide Star System (LGS). The LGS provides real- time adaptive optics correction using an artificial, laser-fed star to correct the distortions of the atmosphere. The two nuclei of Arp 220, separated by 1.0 arsec, were resolved, the brighter to the west (right) and the more diffuse to the east. The upper images (where the brightness is colour-coded) show the appearance in molecular gas (left) and stellar light (right). The two lower images show the behaviour of the velocities of the gas (left) and the stars (right); the colour-coded images here depict matter moving towards the observer (in blue) and moving away (red). It is apparent that the stars and the gas move differently: the stars in two counter-rotating discs Gas velocity Stellar velocity and the gas in a larger-scale disc. The image is taken from ESO PR 27/07, which provides more details.

46 The Messenger 128 – June 2007 Astronomical Science

GHostS – Gamma-Ray Burst Host Studies

Sandra Savaglio1 shift was measured in 1997, when GRBs The GRB host galaxy population Tamás Budavári 2 were finally confirmed to be cosmologi- Karl Glazebrook 3 cal sources. Today there are 108 GRBs There is no doubt that studies of GRB Damien Le Borgne 4 with measured redshift, the highest being host galaxies are entering into a realm of Emeric Le Floc’h 5 GRB 050904, at z = 6.3. The typical galaxy formation that was hardly known Hsiao-Wen Chen 6 energy emitted by a GRB, in a couple of before. The reason is that GRB hosts Jochen Greiner1 minutes, is 1051 ergs, equivalent to the are generally faint and detected at high Aybuk Küpcü Yoldas¸ 1 energy emitted by the sun in 10 billion redshifts. Similar galaxies are very hard years. to find using conventional techniques, because they would require very long 1 Max-Planck Institute for Extraterrestrial Today GRBs are primarily discovered by integration times, even for the largest and Physics, Garching, Germany the satellite Swift (http://swift.gsfc.nasa. most efficient telescopes. 2 Johns Hopkins University, Baltimore, gov), the dedicated NASA mission which USA in two years of operation helped to double GRB events offer a shortcut to the quest 3 Swinburne University, Melbourne, the number of measured redshifts. With for faint and distant galaxies. They are Australia the growing data collected from space detected as short and energetic events. 4 CEA-Saclay, Gif-sur-Yvette Cedex, and ground telescopes, and the advent The localisation (and for a fraction of France of Swift, our group decided to create a them the redshift) is measured from the 5 Institute for Astronomy, Honolulu, database, available to scientists, which bright X-ray and optical afterglow. We Hawaii collects observational results on the gal- know that long-duration GRBs occur in 6 University of Chicago, USA axies hosting GRB events. We called it regions of star formation, therefore, they GHostS, or GRB Host Studies. Our focus are associated with galaxies. Dedicat- is to explore and unveil the nature of gal- ed programmes can observationally com- GHostS is the largest public data-base axies in which GRBs occur. Our goal is to plete the investigation. on gamma-ray burst (GRB) host galax- answer fundamental questions, such as: ies and is accessible at the URL http:// are these galaxies different from the gen- In our GHostS search, we want to explore www.grbhosts.org. Started in 2005, it eral galaxy population; are they special in many of the most interesting galaxy pa- currently contains photometric and any way; can we use them to understand rameters, such as metallicity, star-forma- spectroscopic information on 39 GRB galaxy formation under extreme condi- tion rate, stellar mass, age of the stellar hosts, almost 2/5 of the total number tions? population and dust extinction. Each of of GRBs with measured redshift. It will these parameters are very difficult to de- continue to grow, together with the un- Today the GHostS database includes rive. One difficulty is the faintness of the stoppable data flow from the obser- results for 39 GRB host galaxies. This is typical GRB host. Moreover, the data ob- vatories all over the world, every time a large number, considering that only tained by the community are often not a new event is discovered. Among 108 GRBs have known redshift (see Fig- homogeneous. To complicate the picture, other features, GHostS uses the Virtual ure 1). the tools often used to derive the physical Observatory resources. quantities are affected by systematic uncertainties which are sometimes greater than the relations being derived. The Gamma-Ray Burst phenomenon

Gamma-ray bursts (GRBs) are the most energetic events in the Universe, and also among the fastest. They are associ- 12 ated with the death of massive stars (core collapse supernovae) or the merging of 10 compact objects, such as neutron stars and black holes. During the explosive 8 phase, they emit most of their energy as a collimated flux of gamma-ray photons from neutrino-antineutrino annihilations, 6 Number and as gravitational waves. The gamma emission lasts from a few milliseconds to 4 a few minutes. 2 The first GRB was discovered in 1967, by the US military satellite Vela, but it took Figure 1: Redshift distribution of all 0 GRBs (empty histogram) and the six years, until 1973, for the first paper to 0 321 4 5 6 7 appear in a scientific journal. The first red- subsample of GRBs included in the Redshift GHostS database (blue histogram).

The Messenger 128 – June 2007 47 Astronomical Science Savaglio S. et al., GHostS – Gamma-Ray Burst Host Studies

The typical GRB host is a star-forming, 9 Figure 2: Histogram of the stellar mass low-mass and low-metallicity galaxy, de- of GRB host galaxies in the redshift 8 interval 0 < z < 6.3, from the GHostS tected at redshift below z = 2. The mean sample. The mean stellar mass is stellar mass we derived in our sample 7 of the order of the stellar mass of the is similar to the stellar mass of the Large Large Magellanic Cloud. This is ten Magellanic Cloud (Figure 2). Observation- 6 times smaller than the stellar-mass limit reached by the deepest high- al limitations prevent us from fully explor- redshift galaxy surveys, performed by ing the same parameters in GRBs at 5 todays’ largest telescopes. larger redshift, but in exceptional cases. 4 The detection of the cold interstellar me- Number dium in high-redshift hosts indicates that 3 there the population is different, with larger stellar masses, higher star-forma- 2 tion rates and higher metallicities (Berger et al. 2005, Fynbo et al. 2006, Savaglio 1 2006). It is still unclear if this means a 0 different population, or different observa- 7 98 10 11 12 tional biases. Such issues will be faced log M�(M�) and fully exploited by the future generation of telescopes and instruments. Figure 3: Example of the In general, we know that GRB hosts are GHostS database web pages. Each GRB entry very peculiar galaxies. We still do not includes basic informa- know whether this is because our tradition on the event, togeth- tional observational technique cannot er with access to rele- reach the extreme limits attained by GRB vant papers available in the literature. It reports detections, or because GRB hosts are in- multi-band photometry, trinsically different. The main limitation is fluxes of emission lines the small number of galaxies discovered and images of the field. so far. This number is still below 100, while the number of galaxies in today’s surveys exceed 105.

The GHostS database

GHostS includes GRB hosts for which photometric and spectroscopic information is available from the literature (Fig- ure 3). In total 39 galaxies, out of a total of 108 GRBs whose redshift is known, have been gathered from 81 different papers and sources. 7 10–17 Figure 4: Very Large Telescope spectrum of the galaxy hosting –17 One of the spectra in the GHostS data- 6 10 GRB 990712 at redshift base is shown in Figure 4. The galaxy z = 0.433 (Küpcü Yoldas¸ hosting GRB 990712 at redshift z = 0.433 5 10–17 et al. 2006). was observed at the Very Large Telescope /s/Å) (Küpcü Yoldas¸, Greiner, Perna, 2006). It 2 4 10–17

has very strong emission lines, originating ] ] in regions of the galaxy where star forma- III III [O 3 10–17 [O tion is very active. We derived a stellar Flux (erg/cm ]

9 II mass of the galaxy of a few times 10 MA, –17 β

2 10 [O H similar to the stellar mass of the Large ] III

Magellanic Cloud, but it forms stars γ

–17 [Ne at a rate that is ten times higher, about 1 10 H –1 6 MA yr . This gives a specific star for- 0 mation (the SFR per unit stellar mass) of 5000 5500 6000 6500 7000 7500 100 times that in the Milky Way. Similar Wavelength (Å)

48 The Messenger 128 – June 2007 galaxies hosting GRBs are detected up to a distance when the Universe was less 1� N than 1 Gyr old. They are very hard to find using normal tools of investigation. Most surveys, probing the high-redshift Uni- verse today, can reach, in terms of stellar mass, galaxies similar to or larger than the Milky Way. E W It is generally not easy to collect results published by the GRB community, because the number of papers available for each event can be large. One extreme case was GRB 060218, which occurred in February 2006, at redshift z = 0.0335, S associated with a supernova, detected three days after the alert (Masetti et al. 2006). In about a year and a half, more vey (POSS, SERC). Other types of auto- Figure 5: One example of the tools offered than 20 articles dedicated to this event mated searches are also in the works, by GHostS. The images show the field of GRB 050509b, at redshift z = 0.2248 (Gehrels et al. have been published (or are in the proc- e.g., for finding spectra at the given posi- 2005), obtained from the Sloan Digital Sky Sur- ess of being published) in refereed jour- tion. These VO additions, the efficient vey (left) and Digitalized Sky Survey (right) archives, nals, four of which appeared in Nature. database, and the presentation of the through the Virtual Observatory. scientific data, make the website not only This proliferation of material is one of an invaluable research tool for GRB host bers would be larger if we were able to the main motivations for the existence of studies, but also very enjoyable to navi- observe all GRB afterglows early on. In GHostS. Observational results are gate. GHostS will feature in the future ad- fact, 2/3, of the Swift GRBs have no mea- searched, collected, homogenised and vanced search capabilities for the com- sured redshift. The fractions of z > 4 and made easily accessible for the whole munity, fine-tuned for astronomical data z > 5 known QSOs are 0.8 %. and 0.03 % community. The database is constantly and will eventually dynamically search VO of the total, with only 17 QSOs known growing in terms of total number of resources for relevant observations, such with redshift larger than 5. objects, and in terms of tools offered. We as images and spectra. plan to eventually include all host galax- Particularly impressive was GRB 050904, ies discovered in the past and in the fu- the record holder at z = 6.3 (Kawai et al. ture for the years of operation of Swift, The future 2005). This GRB was observed with the and it will likely contain a final sample of a Japanese telescope Subaru more than few hundred galaxies. The future of GRB science fully depends three days after the Swift alert, when it on the life of GRB hunting machines, had already faded 11 magnitudes from its i.e. gamma-ray detectors. Today it almost initial brightness. Fortunately at high red- The Virtual Observatory exclusively relies on the existence of shifts the brightness of a fading object Swift, which has been funded for an ad- is helped by time dilation, the effect de- The Virtual Observatory (VO) is one of the ditional four years. scribed in Einstein’s theory of General features offered in our database. The Relativity. If this GRB had occurred in the VO is one of the newest and most prom- Among the many unexplored territories, local Universe, it would have faded at ising tools introduced in the astronomy we mention the discovery of the very a rate more than seven times faster. The world, allowing scientists to easily access high redshift GRBs, at z > 6. We know spectrum of this spectacular event is data from multiple astronomical obser- that there are collapsed objects at those shown in Figure 6 (from Totani et al. 2006). vatories, both ground- and space-based times. We do not know under which The host galaxy is barely detected by the facilities, through one portal (see for in- physical conditions these objects formed: Hubble Space Telescope and Spitzer stance http://www.us-vo.org/). Its com- are they stars, galaxies or massive black Space Telescope (Berger et al. 2006). We ponents have been added to the GHostS holes? At z > 6, QSO searching has failed estimate a stellar mass which is half web portal (Figure 5). Using information in providing a satisfactory picture, and that of the Large Magellanic Cloud, and a about the GRBs and their hosts stored galaxies are incredibly hard to find. GRBs rate of star formation ten times higher. Al- inside our SQL database, one can auto- on the other hand have shown some though this event happened less than matically enhance the view of the cata- very promising results. In the first two 900 million years after the Big Bang, the logued hosts by using various VO re- years of operations, Swift has discovered absorption lines detected in its spectrum sources. The details pages currently show 8 GRBs at redshift larger than 4, and 4 indicate a surprisingly high pollution of images of the relevant pieces of the sky at redshift larger than 5. This is 7% and heavy elements in the interstellar medium as seen by the Sloan Digital Sky Survey 3.5 % of the total GRB population with in the host galaxy, of the order of 1/10 (SDSS) and the legacy Digitized Sky Sur- measured redshift, and probably the num- that of the solar vicinity (Totani et al. 2006;

The Messenger 128 – June 2007 49 Astronomical Science

Figure 6: Subaru spectrum of the most distant GRB ever discovered, GRB 050904 at z = 6.3 (Totani et al. 2006). It was observed more than three days after the alert given by the gamma-ray burst finder Swift, when it had already faded 11 magnitudes from its initial brightness. Savaglio 2006). This is hardly explained by most theories of chemical enrichment in the primordial Universe. Galaxies 1.5 like these are very likely faint and dormant today, because they would have con- ) 1 sumed their gas reservoir for star forma- –1 tion in less than one Gyr, i.e. by redshift Å –1 z = 3. s

–2 0.5 If GRB 050904 were observed two hours GRB 050904 after the Swift alert, its spectrum would 3.4 days

erg cm 0

have been much more spectacular, with –18

a signal-to-noise ratio ten times better (10 λ (C IV) S II O I C II than that of the Subaru spectrum. Noth- F –0.5 ing like this has ever been achieved in the Lyα + Si II 1 errors remote Universe with normal galaxies σ or QSOs. It is only a matter of time that, –1 8600 8 800 9 000 9 200 9 400 9 600 9800 10 000 sooner or later, Swift will trigger similar Observed wavelength (Å) events at higher redshift. Then telescopes from the ground will be ready to catch the fading sources and deliver a unique data set to the scientific community, for References Kawai N. et al. 2005, GRB Coordinates Network new exciting discoveries. We will be there 3937, 1 Berger E. et al. 2005, ApJ 642, 979 Küpcü Yoldas¸ A., Greiner J. and Perna R. 2006, to continue our service to the community Berger E. et al. 2006, ArXiv Astrophysics e-prints, A&A 457, 115 with GHostS, in the attempt to fully char- arXiv: astro-ph/0603689 Masetti N. et al. 2006, GRB Coordinates Network acterise those galaxies parenting one of Fynbo J. P. U. et al. 2006, A&A 451, L47 4803, 1 the most extraordinary objects in the Uni- Gehrels N. et al. 2005, Nature 437, 851 Savaglio S. 2006, New Journal of Physics 8, 195 Totani T. et al. 2006, PASJ 58, 485 verse.

The Rapid-Eye Mount (REM) 0.6-m telescope at the ESO La Silla Ob- servatory, which is dedicated to the follow-up of gamma-ray bursts, is shown in operation. ESO PR 26/07 provides details of the telescope and some science results.

50 The Messenger 128 – June 2007 Astronomical Science

The Puzzle of the Lya Galaxies: New Results from the VLT

Christian Tapken1 able. Because of the large distance, the about 0.5, that neither galaxy formation Immo Appenzeller 2 light emitted by the young galaxies as far- nor star formation was well understood, Armin Gabasch 3,4,5 UV radiation is redshifted to the red and that the most advanced astronomical Jochen Heidt 2 near-infrared spectral range. Hence, the detectors were image tubes followed by Ulrich Hopp 3,4 detection of such objects requires obser- photographic plates, and that there ex- Ralf Bender 3,4 vations at these wavelengths. isted only two astronomical telescopes Stefan Noll 3,4 with apertures exceeding 2.5 m. Since in Stella Seitz 3,4 As the most promising way to find these 1966 getting time at the largest existing Sabine Richling 6 objects, Partridge and Peebles proposed telescopes was probably as difficult as to search for their Lyman-a (Lya) line today, Partridge and Peebles assumed emission. This spectral line, due to transi- for their feasibility estimates a more mod- 1 Max-Planck-Institut für Astronomie, tions from the first excited energy level est (and more typical) 90-cm telescope, Heidelberg, Germany to the ground state of hydrogen atoms, is equipped with an image tube with an 2 Landessternwarte Heidelberg-König- important in many astrophysical proc- S1 cathode. With these assumptions stuhl, Heidelberg, Germany esses. In normal galaxies Lya emission is Partridge and Peebles predicted that the 3 Universitäts-Sternwarte München, produced during the recombination of Lya emission of very young galaxies Germany interstellar hydrogen gas, which has been at z ≈ 7 should be detectable with an 4 Max-Planck-Institut für Extraterres- ionised by hot stars. Simple estimates exposure time as short as five minutes(!). trische Physik, Garching, Germany show that up to about 2/3 of the Lyman 5 ESO continuum photons (and up to about 6% 6 Institut d’Astrophysique de Paris, France of the total luminosity) of hot stars can The search for the Lya emitting galaxies be converted into Lya photons. This also means that, in principle, Lya emission Prompted by the 1967 paper, many dif- Observations of high-redshift galaxies equivalent widths of the order 100 to ferent groups started searching for red- show that at early cosmic epochs the 200 Å can be expected in the spectra of shifted Lya (and UV continuum) emission cosmic UV radiation field appears to be such galaxies. of high-redshift galaxies. However, al- dominated by small galaxies with strong though a large amount of observing time Ly-alpha emission. Although usually Of course 6 % is still only a minor fraction was invested, and although the surveys small and of relatively low luminosity, of the total emitted luminosity. However, soon reached much fainter magnitudes these galaxies are easily identified from as noted by Partridge and Peebles, in the than those predicted by Partridge and their line emission. Observations with small wavelength range covered by the Peebles, for many years no redshifted the VLT resulted in significant progress Lya line, the expected spectral flux densi- Lya emitting galaxy was found. Some in the understanding of the nature of ty is much higher than in the adjacent Lya emission was detected from distant these distant galaxies and of their role continuum. Therefore, detecting the line radio galaxies and from some galaxies in the early Universe. emission against the strong sky back- associated with distant QSOs. However, ground in the red spectral range ap- it was not clear whether starbursts or peared much easier than looking for the non-thermal ionising sources were re- The pioneers: R. B. Partridge and continuum emission. sponsible for the Lya emission from these P. J. E. Peebles objects. In 1967 sensitive astronomical detectors The history of the Lya galaxies began in were limited to wavelengths ≤ 1 µm. Thus, Starting about 1995, many galaxies with 1967 with a pioneering paper by R. B. observations of the redshifted Lya line redshifts of z ≈ 3 were discovered using Partridge and P. J. E. Peebles. In this arti- appeared feasible only up to redshifts the Lyman-break technique. Practically all cle, published in the Astrophysical Jour- where the observed wavelength of Lya the distant galaxies found with this tech- nal, the two Princeton University astro- does not exceed 1mm, which means red- nique showed clear spectroscopic sig- physicists discussed the formation of the shifts z = ∆λ/λ ≤ 7. In view of this limita- natures of strong starbursts. However, in first galaxies in the Universe. They con- tion, Partridge and Peebles calculated most cases the Lya line occurred ei- cluded that the first galaxies probably the emitted luminosity and the expected ther in absorption or as a relatively weak began their lives with strong initial bursts observed Lya flux emitted at an epoch emission feature. Similar results were of star formation at cosmic epochs cor- corresponding to z ≈ 7. found for samples of high-redshift gal- responding to redshifts between 10 and axies selected on the basis of photomet- 30. Because of the presence of many To appreciate the courage and foresight ric redshifts (see Figure 1). massive, hot, and luminous stars in these of taking up this topic in 1966, when the starbursts, Partridge and Peebles pre- paper was submitted, we have to recall More detailed models of starburst gal- dicted very high ultra-violet (UV) luminosi- that the Cosmic Microwave Background, axies soon provided a plausible explana- ties of the newly formed galaxies, and confirming the present cosmological tion for the weakness of the Lya emis- they estimated that the light emitted by concepts, had been discovered just one sion of the young z ≈ 3 galaxies. Partridge such objects during the first few hundred year before, that the most distant galaxy and Peebles were certainly correct, million years should actually be observ- known at that time had a redshift of noting that in young starbursts copious

The Messenger 128 – June 2007 51 Astronomical Science Tapken C. et al., The Puzzle of the Lya Galaxies: New Results from the VLT

numbers of Lya photons are produced. 25 Figure 1: Distribution of the Lya However, because of the high absorption emission equivalent widths in samples of high-redshift galaxies selected cross-section of hydrogen atoms for Lya 20 using broadband photometry. The photons, even a small amount of neutral histogram is based on the FDF hydrogen can make a galaxy completely spectroscopic survey (Noll et al. 2004), opaque for Lya. 15 selected on the basis of photometric redshifts. The blue line shows the distribution derived by Shapley et al.

Normally the absorption of Lya by an in- Frequency 10 (2003) for Lyman-break-selected terstellar hydrogen atom will be followed galaxies. by a re-emission at the same frequency. Thus, hydrogen atoms essentially scat- 5 ter the Lya photons, which in principle can still escape after some random walk 0 0 100 200 300 through the neutral hydrogen layer. How- Lyα emission equivalent widths (Å) ever, the resonance scattering greatly increases the effective light path of these cally faint and small (see Figure 2). On the lithium) is composed of hydrogen and he- photons. Therefore, even a small amount other hand, the relatively high space den- lium. Under astrophysical conditions of truly absorbing material embedded in sity of the distant Lya galaxies derived by neither hydrogen nor helium can form the scattering layer will result in the even- Hu et al. indicated that the Lya galaxies solids. Thus, dust particles can form only tual absorption of the Lya photons. A provided a major contribution to the star after heavier chemical elements have most efficient UV absorber is interstellar formation and to the cosmic radiation been produced by the nuclear processes dust, which is normally abundant in star- field at the corresponding epochs. Never- in stars. A very important first result of forming regions. Thus, the combination of theless a reliable assessment of the ef- the VLT observations was high-quality resonance scattering by neutral hydrogen fects and the importance of the Lya gal- FORS spectra of Lya galaxies showing and dust absorption provides a highly axies required more information on their conspicuous lines of heavy elements (Fig- plausible explanation for the absence detailed properties and their density as a ure 3). In particular, these spectra con- of strong Lya emission in most known function of redshift. Therefore, the first tained lines of carbon and silicon, which young galaxies. It also seemed to explain results immediately started a new wave of are among the main constituents of inter- why more than two decades of searches searches for high redshift Lya galaxies. stellar dust particles. for high-redshift Lya galaxies were not In addition, new studies of the physics of successful. these objects were triggered. Some of If dust is present in young galaxies, Lya this new work was carried out at ESO us- photons can still escape, if the dust and Soon after the above explanation for the ing the VLT. In the following we describe (or) the neutral hydrogen are distributed absence of strong Lya emission in dis- new results on the nature and the space inhomogeneously and if, by chance, no tant starburst galaxies, and the reason for density of these distant galaxies which such material is present along the line of the futility of the earlier searches had resulted from these VLT observations. sight between us and the starburst. That been more or less accepted, the history the amount of dust and cool material of the Lya galaxies took an unexpected along the line of sight plays a role for the turn in the mid-1990’s. The first Lya gal- The mystery of the strong line emission observed Lya flux is supported by the axies were detected on the basis of their finding that the Lya emission strength of strong emission line. In an ApJ letter As described above, for many years as- high-redshift galaxies decreases with of 1998 Ester Hu, Lennox Cowie, and tronomers were puzzled by the fact that increasing dust reddening and that the Richard McMahon reported the discovery no Lya galaxies could be observed. That Lya emission is lower in galaxies with of the elusive high-redshift Lya galaxies they were finally discovered in the mid- strong interstellar absorption lines, typical during observations with the new 10-m 1990’s resulted in a new big mystery. The for cool interstellar gas (Shapley et al. Keck II telescope. The objects discovered question now was, why these galaxies 2003, Noll et al. 2004). However, for a by these authors had redshifts of z ≈ 3.4 could emit such a strong Lya flux in spite given reddening, the Lya emission and z ≈ 4.5 and Lya emission equivalent of the expected quenching of the Lya strength tends to vary considerably and widths > 100 Å. However, their luminos- photons by the combination of resonance there exist Lya galaxies with high Lya ities were only about one hundredth of scattering and dust absorption. As a pos- equivalent widths and a modest amount that predicted by Partridge and Peebles. sible answer to this question it was sug- of reddening. Thus, missing dust and/or This obviously explains why it took a tele- gested in the literature that the Lya galax- missing neutral hydrogen along the line scope of 10 m (instead of 1 m) aperture to ies were too young to have formed heavy of sight cannot fully explain the observed find them. chemical elements, which are needed strong line emission. to form dust. This explanation appeared From the large Lya equivalent widths, it plausible, since the first galaxies are ex- Another mechanism, which can avoid the was clear that the faintness of these pected to form from primordial matter quenching of the Lya emission, is the objects was not due to dust absorption. produced by the Big Bang, which (apart presence of sufficiently large velocity Obviously, these galaxies were intrinsi- from tiny amounts of deuterium and gradients in the neutral gas. If a hydrogen

52 The Messenger 128 – June 2007 Figure 2: Examples of HST/ACS FDF-4691 FDF-3389 FDF-5812 F814W images of three Lya galaxies.

5 kpc 5 kpc 5 kpc

10 Figure 3: FORS spectrum of the Lya compact, strong starbursts. The combi- galaxy FDF-4691 (from Tapken et al. FDF-4691 nation of the relatively broad intrinsic Lya 2004). 8 profiles and the expansion of a neutral

α hydrogen shell readily explains the fact γ β IV ) IV II V –1 Ly C Si C N Ly Ly–lim Ly Å that a major fraction of the Lya photons –2 6 can escape, in spite of the presence of Wm

–21 a dusty neutral hydrogen shell in front of 4 the emitting region. Flux (10 From our results, we conclude that, al- 2 though a relatively small amount of neutral matter along the line of sight cer- 0 4 000 5 000 6 000 7000 tainly plays a role, the high intrinsic Wavelength (Å) velocity dispersion of the emitting ionised gas and large-scale outflows of the atom is moving relative to the volume We have used the VPH grisms available neutral hydrogen are the main reasons for emitting the Lya line with a velocity larger on the FORS instruments to obtain the escape of a large fraction of the Lya than the line widths, the atom cannot medium-resolution spectra of a sample of photons from the observed galaxies. The absorb or scatter the Lya photons. In this Lya emitting high-redshift galaxies in small continuum flux (relative to other case the Lya photons can penetrate the the FORS Deep Field (Appenzeller et al. high-redshift galaxies) indicates a low neutral hydrogen layer and escape. Such 2004). The observed Lya profiles were total mass of the hot stars of Lya galax- velocity differences are not unexpected compared to model profiles, which were ies. If the mass of the hot stars is a mea- since the velocity of sound is much computed using the radiative transfer sure of the total mass of these objects, higher in the hot Lya emitting gas than in code of Meinköhn and Richling (2002), Lya galaxies are probably of lower (and the cool neutral hydrogen layers. Thus, which is particularly well suited for mod- more normal) mass than other known assuming turbulent media with subsonic elling resonance scattering in moving high-redshift galaxies. Therefore, they turbulence, the Lya lines emitted by media. Examples of the observed profiles probably have lower gravitational poten- the hot ionised gas are expected to have and model fits are presented in Figure 4. tials, which may explain the observed profiles which are significantly broader For these computations (described in strong outflows. than the velocity dispersion of the scat- detail in Tapken et al. 2007) we assumed tering layers. However, because of the a central volume of turbulent, ionised very high absorption cross-section of hydrogen, emitting the Lya radiation. This The space density of Lya galaxies and neutral hydrogen, even the outer wings of region was assumed to be surrounded by their role in cosmic evolution the absorption profiles can prevent the a shell of dusty neutral hydrogen. escape of the Lya photons. On the other As noted above, most known Lya galax- hand, it can be shown that the probability The calculations showed that the ob- ies are small and have intrinsically faint for an escape of the Lya photons can served profiles could be reproduced rea- UV continua. However, already Hu et al. increase strongly if large-scale velocity sonably well with this model, if a modest (1998) found for the redshift range 3.4 < fields are present in the scattering layers. (10–200 km s–1) expansion velocity of z < 4.5 a total star-formation density due Mechanisms producing such large-scale the neutral hydrogen shell was assumed. to the Lya galaxies which is comparable velocity fields can be mass infall, or mass From the observed line wings (which are to that due to all other known high-red- outflows from the galaxies powered by not much affected by the neutral hydro- shift galaxies. Since Lya galaxies tend to stellar winds or radiation pressure from gen shell) high velocities (> 600 km s–1) of be less affected by reddening than other the central stars. Since such velocity the ionised gas could be derived. These high-redshift galaxies, they are expected fields also affect the profiles of the Lya high velocities can be explained by super- to dominate the UV radiation field at these lines, line profile observations provide a sonic turbulence caused by supernova redshifts. Moreover, studies of high-red- critical test of this hypothesis. shocks and strong stellar winds in the shift galaxy samples based on photomet-

The Messenger 128 – June 2007 53 Astronomical Science Tapken C. et al., The Puzzle of the Lya Galaxies: New Results from the VLT

Figure 4: Examples of observed (black) and computed (red) Lya emission line profiles of Lya emitting galaxies.

5 20 15 FDF-4691 FDF-5215 FDF-7539 4

15 3 10 Flux Flux Flux 10 2

5 5 1

0 0 0 –2000 –1000 0 1000 2000 –1000 0 1000 –1000 0 1000 2 000 –1 –1 Velocity (km s–1) Velocity (km s ) Velocity (km s ) ric redshifts (and, therefore, relatively free was an extension of the luminosity func- dows’ covers about 20 nm wavelength of selection effects) show that the fraction tion to lower luminosities, which was pos- interval near l = 815 nm (corresponding of Lya emitting galaxies is increasing with sible as a result of the superior sensitivity to a Lya redshift of z ≈ 5.7). This win- redshift (Noll et al. 2004). According to of the FORS2 instrument and a spe- dow is particularly important since, at this Shimasaku et al. (2006) at z = 6 about cially developed set of narrowband filters wavelength, photometric and spectro- 80% of all high-redshift galaxies are Lya (Tapken et al. 2006). scopic follow-up observations are still rel- galaxies with intrinsic Lya emission equiv- atively easy. Therefore, this window was alent widths > 100 Å. Hence, at very Like all current searches for Lya galaxies, also used for our VLT observations. To high redshifts these objects are expected the survey carried out with the VLT used reach an optimal sensitivity, the wave- to strongly dominate the cosmic UV radi- sky images obtained through a combina- length interval of the 815-nm OH window ation field and the cosmic ionisation. tion of broadband and narrowband fil- was covered by a set of three filters (Fig- ters. Normal galaxies, where the light is ure 6). In this way it is possible not only to For a more quantitative assessment of dominated by the stellar continua, tend avoid the strong OH lines outside the the role of the Lya galaxies in the early to be visible with a similar brightness in window, but also to partially suppress the Universe obviously a reliable knowledge many different filter bands. Emission-line weaker lines still present inside the of their space density as a function of objects are characterised by an excess 815-nm OH gap. Because of the resulting luminosity and redshift is needed. There- emission in one or, if the emission line co- lower background, the VLT observations fore, during the past years, various differ- incides with the overlap region of two allowed us to reach significantly lower ent groups have invested much work to filters, in at most two adjacent filter bands Lya luminosities than had been possible derive this so-called ‘luminosity function’ (see Figure 5). Filter photometry allows a before. of the Lya galaxies at different redshifts. reliable detection of galaxies which have There were basically two types of such emission lines in their spectra. More dif- Figure 7 shows the results together with programmes: firstly, large-area surveys ficult and more complex is the unambigu- luminosity function data from another were used to improve the number statis- ous identification of the observed emis- recent survey. The new data confirm the tics of these objects; secondly, very deep sion lines as Lya. For this purpose one high space density of faint Lya galaxies observations in smaller fields were used needs reliable photometric redshifts and at high redshift. In particular up to z ≈ 6 to reach fainter Lya galaxies and to derive low-resolution spectra of the candidate the space density seems not to decrease the faint part of the luminosity function for galaxies, which rule out other identifica- with redshift. On the other hand, the ob- these objects. This faint part is important, tions of the observed lines. served luminosity range and the number since, within the observational limits, faint of observed objects are still too small, to galaxies are always more numerous than In order to reach an optimal signal-to- constrain the luminosity function well. the bright ones. noise ratio, the passbands of the narrow- Although much progress has been made, band filters used for searches of Lya obviously more work is needed to derive Particularly successful among the large- galaxies are designed to coincide with the radiation field produced by the Lya area surveys were studies carried out wavelength regions of particularly low galaxies with an adequate accuracy. with the wide-field SUPRIME camera of night sky background. Since most of the the Japanese national telescope Subaru night sky background in the red and (see, e.g., Shimasaku et al. 2006). These near-infrared is due to airglow produced Future work and outlook surveys resulted in important informa- by OH molecules in the high atmosphere, tion on the space density of luminous Lya the spectral regions of low sky back- Several ambitious large-area searches for galaxies and on the cosmic variance of ground are the gaps or ‘windows’ in the Lya galaxies are underway which will this quantity. Our contribution to the topic OH line spectrum. One of these ‘OH win- further improve the statistics of these ob-

54 The Messenger 128 – June 2007 Figure 5: Bessell-R and broadband images and narrowband images of four galaxies in the FORS Deep Field. The upper two panels show z ≈ 5.7 Lya galaxies. The lower two panels show, for comparison, corresponding data for a normal z ≈ 3.2 starburst galaxy and for a z ≈ 1.2 [O ii] emitter. jects. Of particular interest will be the R I 8100_70 8150_50 8150_60 results of the DAzLE survey, which, using infrared imaging, aims at finding Lya galaxies at redshifts z > 7. Hence, during the FDFLAE-12 next few years we will certainly see much more and better statistical data on the bright part of the luminosity function of the Lya galaxies. Less clear is the outlook for more information on the important faint part of the luminosity function of FDFLAE-13 these objects. Reaching significantly fainter galaxies with normal deep-field observations would require very long exposures times, which appear not realistic for such programmes. More promising may be the ‘gravitational telescope’ tech- FDF-1999 nique, i.e., making use of the flux amplifi- cation of distant objects by strong gravitational lensing. Because of their relatively high surface density, Lya galaxies are well suited for such programmes. Estimates have shown that, with presently available FDF-5115 instruments, observations of lensed Lya galaxies in the field of a single galaxy cluster with a high lensing strength (such as the ROSAT source RX J1347-1145) could provide a significant sample of Lya galaxies with intrinsic luminosities one to 4 Figure 6: Spectrum of the OH airglow several magnitudes fainter than those near the 815 nm window. Overplotted are the transmission curves of the known at present. These data could be special FORS2 narrowband filter set obtained with a rather modest amount of 3 for detecting Lya galaxies at redshifts observing time. Thus, progress concern- ≈ 5.7. ing the luminosity functions also seems to be possible, provided observing time 2 Flux for such programmes can be obtained.

1 Acknowledgements

Our research has been supported by the German Science Foundation DFG (SFB 439). We would like 0 7900 8000 8100 8200 8300 8400 to thank the staff of the Paranal Observatory for Wavelength (Å) carrying out the service mode observations. We also thank Dörte Mehlert and Erik Meinköhn for discussions and valuable comments.

–2 Figure 7: The luminosity function of References Lya galaxies at z = 5.7. Tapken et al. 2006

Appenzeller I. et al. 2000, The Messenger 116, 18 Shimasaku et al. 2006 Hu E. M., Cowie L. L. and McMahon R. G. 1998, ApJL 502, L99 –3 /log lum)

Meinköhn E. and Richling S. 2002, A&A 392, 827 3 Noll S. et al. 2004, A&A 418, 885 Partridge R. B. and Peebles P. J. E. 1967, ApJ 147, 868 Shapley A. E. et al. 2003, ApJ 588, 65 –4 Shimasaku K. et al. 2006, PASJ 58, 313

Tapken C. et al. 2004, A&A 416, L1 log (number/Mpc Tapken C. et al. 2006, A&A 455, 145 Tapken C. et al. 2007, A&A 467, 63

–5 35 35.5 36 36.5 37 log Lyα luminosity [W]

The Messenger 128 – June 2007 55 Astronomical News 200 3 at Museum Site ALMA the near view landscape Atacama m.

Photo: H. H. Heyer, ESO Astronomical News

Nature Around the ALMA Site – Part 2

Figure 1: The vegetation Michel Grenon Valeriana nivalis belts as described (Geneva Observatory, Switzerland) Festuca chrysophylla Mulinum crassifolium m by Richter (2003) on the Adesmia spinosissima Deyeuxia curvala slopes of Sairecabur Baccharis tola Pycnophyllum bryo 5 500 volcano, NW of ALMA, The natural environment around the Parastrephia quadrangularis with indication of char- oVg ALMA site, its flora, fauna and land- Fabiana denudata 5000 acteristic plants. scape morphology, are presented and Junellia seriphioides interpreted in terms of combined geo- Trichocereus atacamensis 4500 logical and climatic evolution with, in Atriplex imbricata parallel, the necessary biological adap- Opuntia camachoi 4 000 tions. This part covers vegetation and 3 500 animal life. uVg 3 000 Sairecabur The vegetation belts Figure 2: The Maihuen- The vegetation belts contain plant asso- iopsis pillows show the effect of the katabatic cations adapted to a given range of at- winds. The side exposed mospheric parameters, soil composition to the cold flow is red- and texture. A recent phytosociological der, an indication of a survey by Richter (2003) provides vege- higher content in antho- cyanine, a molecule tation transects in the ALMA area, namely acting as anti-freeze. at Sairecabur, Toco Toco and Miñiques (Figure 1). On the western slopes of Toco Toco, all belts are present, because the rocks are old enough to have been altered into sand and clay, and hence are able to retain water.

At the lowest level, 2 900–3 350 m, the limiting factors are the scarcity of precipitation, the high evapotranspiration and the salt and nitrate content in the soil. Atriplex communities – tall greyish bushes Figure 3: Thanks to the – develop on the shore of the Atacama reduction of the leaf size, Fabiana bryoides Salar in salt rich soils. On undisturbed resists dessicating rocky places, the cactus Maihueniopsis winds and may grow up camachoi forms colonies of spiny pillows to 4900 m. (Figure 2), among several other plants. In wind shadow places, the tall cactus Trichocereus atacamensis, an invader from Argentina, grows.

At higher altitudes, evapotranspiration becomes the dominant factor. The efficiency of the evaporation increases with the square of the wind velocity. Low humidity and high wind velocity favour high rates of water loss by the plant epiderm. Several techniques are developed by plants to reduce these losses. suppressed and photosynthesis takes In the zone 3 850–4 300 m, the vegeta- place at the upper stem surface. The tion becomes scarce and the grami- In the second vegetation zone, 3 350– whole plant is varnished with a viscous naceae herbs are dominant. The golden 3 850 m, is found Fabiana bryoides, resin. In other plants, such as some Festuca chrysophylla gives the landscape with leaves reduced to minute rosettes, Senecios, the water losses are minimised its colour and specific character (Figure 4). forming a compact cover on the stem, through the development of a white to- Behind the tufts of Festuca, in the wind mimicking coral branches (Figure 3). In mentum of dense crispy hairs, reflecting shadow, several plant species may de- the same zone, Fabiana denudata repre- the solar radiation and setting the wind velop. Parastrephia quadrangularis is an- sents an extreme case: its leaves are velocity to zero at the epiderm surface. other typical plant with leaves reduced

The Messenger 128 – June 2007 57 Astronomical News Grenon M., Nature Around the ALMA Site – Part 2

to scales, covering the stem as tiles. The Figure 4: Festuca association of Festuca, Parastrephia and chrysophylla forms large populations giving a Baccharis provides the preferred pasture golden aspect to the of guanacos and vicuñas (Figure 5). landscape at altitudes where most bushes, except Parastrephia, have disappeared. The high-altitude vegetation

In the zone 4 350 m to 4 850–5150 m, the wind intensity, the eolian erosion and the temperature are the limiting factors for vegetation. On flat surfaces, plants have to minimise their cross section with respect to the thermal and zonal winds. To expand horizontally is a frequently en- countered adaptation, e.g. by Pycno- phyllum bryoides (Figure 6) and by the Calyceras genus (Figure 7). This strategy is also adopted by some dwarf trees Figure 5: Vicuñas in as Adesmia sp., which develops an under- the altoandine steppe near Maricunga Salar, ground stem and branch systems ex- 3 800 m. tending well below the surface. Leaves are covered with hygroscopic glanduli- ferous hairs able to absorb directly the humidity from the air.

In rocky places, plants may develop provided the soil is evolved. Fresh lava or Figure 6 (below): lapilli cannot retain water close to the sur- Pycnophyllum bryoides face and several centuries of weathering expands as rings on are needed before the first plant colony flat gravel surfaces (left). Leaves are reduced may settle. On older substrates, such as to ovoid cones (right), at Toco Toco, plants use rock cracks, petals are translucid, at wind shadow, to expand their roots in and so the plant offers clay, searching for residual humidity. a minimum surface to dessicating winds. Nototriche holosericea and Chaetanthera revoluta (Figure 9), and Oxalis sp. (Fig- ure 10), are typical examples of this behaviour.

In small valleys oriented NS, perpendicu- lar to the afternoon and zonal winds, the soil and plant evaporation is notice- ably reduced. Snow may accumulate during winter and stay until the next blos- soming season. Plant communities requiring less protection against evapotranspiration may develop up to very high altitudes, as the Werneria-Senecio association, consisting of a dozen different species. Around ALMA, this association is characterised by the presence of Werneria poposa and Valeriana nivalis (Figure 11). In these sites, the limiting factor is the temperature, which reduces the duration of the vegetation period to nearly zero above 4850–4900 m.

58 The Messenger 128 – June 2007 Figure 8: This Adesmia sp. is an underground dwarf tree. Strong spines prevent grazing by viscachas or vicuñas (Toco Toco, 4 500 m).

Figure 7 (above): In Figure 9 (below): In Nototriche holosericea (left) Calyceras genus, the leaves are undulated and cerebriform; the surface hemispherical head of available for gas exchanges exposed to the wind green flowers is the only is manyfold. A white indumentum protects the leaf part emerging above from transpiration and UV radiation. Chaetanthera ground level (Laguna revoluta flowers (right) open on top of 1 cm long Miscanti, 4000 m). cones, covered by hairy leaves (Llano de Pajonales, 4 410 m).

Figure 10: This Oxalis sp. expands along narrow cracks, in sunny places, at Toco Toco, 4 400 m.

The Messenger 128 – June 2007 59 Astronomical News Grenon M., Nature Around the ALMA Site – Part 2

Figure 11: Werneria poposa (left) grows in wet and wind-shadow rocky places, close to Valeriana nivalis Figure 13: Calceolaria stellariifolia is a rare plant (right), a rather common plant reaching the upper found between 4000 and 4300 m around ALMA. Its limit of the vegetation; its thick root is strongly aro- geographical distribution shows a typical area matic, reminiscent of the Celtic Nard (N of Toco disjunction consequent on the postglacial climate Toco, 4 520 m). warming.

Figure 14: Senecio aff. algens grows between dark rocks exposed to the west. The altitude of Toco Toco station, at 5150 m, is the highest for flowering plants observed so far near ALMA.

Figure 12: Four representative plants at the vege- ground), than on bright colours, in order tion limit. As a result, the areas occupied tation limit in humid places at Cerro Toco Toco. to attract hymenopter pollinators whose by high Andian plants are now disjunct. Top left: Calandrinia sp.; top right: Menonvillea sp. (4 820 m); lower left: Perezia atacamensis (4700 m); eyes, or ocelli, are sensitive down to An example of severe area restriction is lower right: Werneria pinnatifida (4700 m). UV-B radiation. that of Calceolaria stellariifolia (Figure 13), found in only half a dozen sites, spread The present geographical distribution of over 1500 km in the high Andes. When high Andes plants reflects the restric- isolated, plants may follow divergent ge- A notable character of the high-altitude tion of areas consequent on the climate netic evolution, they have no chance to flowers is the restriction of their colour warming after the Ice Age. Intermediate merge their genes again before the next range. They look unattractive to the altitude plant communities had to move glaciation. human eye: blue, orange, red colours are up by about 1 km, migrating towards no longer present. Most flowers are the altiplano on gentle slopes east of the Plants reaching the maximum altitude white, yellowish or at best bright yellow Atacama Desert core, or towards the around ALMA belong to the Senecio (Figure 12). With a very low ground top of isolated mountain ranges. Those genus. Senecio Puchii is frequently seen coverage, plants appear to rely more on already growing on the altiplano during up to 4750 m. Senecio aff. algens (Fig- petal UV-reflectivity, (increasing the con- the Ice Age are found presently on iso- ure 14), replaces it at higher altitude, in trast between the flowers and the lated peaks, close to the upper vegeta- sunny places between 4 850 and 5150 m.

60 The Messenger 128 – June 2007 Hot springs and high altitude vegas Figure 15: High andine vegas are formed of compact material, strong Wet biotopes are due either to hot springs enough to resist the in hydrothermal fields as at El Tatio, or weight of vicuñas or to the development of high altitude vegas, even llamas (Chungara, the southern counterpart of peat bog in 4 500 m). the Northern Hemisphere. In the Andes, the bog is made up of a very compact plant interlacing, where the Juncacea Oxychloe andina plays a central role (Fig- ure 15). Water pools are resting places for many birds, including the large andine goose, as well as for migrating birds, transporting seeds from one vega to the next. The vega vegetation is hence very uniform along the Andes. Hot springs Figure 16: Frankenia host highly specialised life forms, adapted triandra grows on warm bumps in the immediate both to high soil temperature and high vicinity of hot springs mineral content, such as Frankenia trian- (El Tatio geyser, 4 350 m). dra (Figure 16), widespread over 1200 km in the Central Andes.

Many more adaptations

Not only plants, but also wildlife, show surprising adaptations to the extreme arid and cold conditions prevailing in North East Chile. As an example, a group of reptiles from the Iguanidae family, the Figure 17: This Lio- genus Liolaemus, has evolved in parallel laemus sp. lizard is perfectly mimetic with to plants, into an incredible number of the rocky environment. species and varieties, able to colonise Able to absorb the solar nearly all biotopes from the margin of the radiation, it may start absolute desert up to the upper vege- hunting in the early morning when the air tem- tation limit. As insects are often uncom- perature is still –25˚C mon, they had to become omnivorous, (Laguna Verde, East of some totally vegetarian. At high altitude, Copiapo, 4500 m). they are adapted to absorb the solar radiation, and hence able to move even if the external temperature is well below 0˚ C. The specimen shown in Figure 17 is an extreme case of this kind of adaptation. vice observations, very few observers metre and submillimetre astronomy by will have the opportunity to visit and enjoy the end of the XXth century. Whether its the unique natural surroundings of Chaj- exceptional qualities will be preserved ... and final remarks nantor, even if Homo sapiens is still not through the XXIst century, depends on yet perfectly tuned to activities above the amplitude of the climate change and After this quick overview of the ALMA site 5 000 m. A more serious concern is the the evolution of precipitation patterns in natural history and climate, and of some expected final extinction of a large frac- the area. Most Global Circulation Models of the adaptations imposed on life – at tion of the high-altitude species as a re- (GCM) predict an aridification of the Ata- the cost of massive extinction – we may sult of the global warming during the cama area, but an increase of wetness appreciate even more the apparent para- XXIst century. A local warming by about and precipitation on the eastern side of dox that scientists had to put the ALMA +3.5˚ C would increase the vegetation the Andes. complex at the upper limit for evolved belts altitude by 500 to 600 m. terrestrial life, to be in a good position to search for molecules in space, progeni- All meteorological, climatic and biological Reference tors of terrestrial and extraterrestrial life. indicators converge to qualify the Chaj- Richter M. 2003, Lyonia 4(1), 1 We may simply regret that, thanks to ser- nantor site as the best possible for milli-

The Messenger 128 – June 2007 61 Astronomical News

Using the h-index to Explore the Scientific Impact of the VLT

Uta Grothkopf, Claudio Melo, time. In this paper, we apply h and h(t) to gramme type, observing cycle, observ- Christopher Erdmann, Andreas Kaufer, selected observatories as well as to the ing mode, etc. In addition, almost all Bruno Leibundgut (all ESO) VLT instruments. respondents investigate their high-impact papers (“most productive instrument, There are several caveats to bibliometric programme, individual authors”, etc.) A The productivity and scientific impact of studies, in particular when used for study of highly cited papers and their observatories and individual instru- comparison across various institutes. De- distribution among facilities is carried out ments are one measure of their suc- spite attempts to synchronise the meth- every year in April at the Space Tele- cess. This article presents the results of ods applied to compile science biblio- scope Science Institute (Madrid and a study where we have applied the graphies, criteria for paper selection are Macchetto 2007). h-index, previously proposed for indi- still defined by the individual observato- vidual researchers, to major ground- ries and are therefore not identical. Simi- All methodologies used by observatories based observatories (VLT, Keck, Gemini, larly, methodologies for building tele- have some advantages and some dis- Subaru) as well as individual VLT instru- scope bibliographies vary (for instance, advantages: counting publications meas- ments. The concept is expanded by retrieval of relevant publications through ures the productivity of facilities, but does exploring the time-dependence of the database (ADS) searches alone, through not indicate whether or not these publi- h-index h(t). Overall, the VLT appears screening of paper journals, etc.). Even cations actually have any influence on the to be among the most successful 8-m- more importantly, comparing telescope advancement of astronomy. Looking at class telescopes. We also show that statistics is problematic because of the the numbers of citations does indicate ESO instruments are making important different features and ways of operation the impact among the astronomical com- contributions to progress in astronomy. of ground-based and space-based tele- munity, but values can easily be inflat- scopes, different apertures and numbers ed by a few extremely highly cited pa- of instruments, different wavelengths pers. Investigating so-called high-impact Introduction of observations, etc. Any comparison has papers and their distribution across ob- therefore to be interpreted with utmost servatories is less biased, but retrieving In order to examine their return on invest- care in order to avoid unbalanced or such statistics is by far not as straight- ment, major observatories around the wrong conclusions. forward as mere publication and citation world have developed metrics to trace counting. their scientific output. Such metrics often focus on the observatories’ productivity Use of bibliometrics by observatories Several in-depth studies have been car- and impact in the scientific community. ried out by Trimble et al. who investi- These two factors are typically measured In preparation for a presentation given at gated productivity and impact of optical, through the number of scientific publica- the IAU General Assembly in Prague, space-based, and radio telescopes, tions based on astronomical data and the Czech Republic in August 2006, we con- respectively (Trimble, Zaich and Bosler, citations these publications generate, re- ducted a survey among large observa- 2005, 2006; Trimble and Zaich 2006). spectively. The methodologies used to tories to better understand what kind of The authors analyse papers, citations compile the ESO Telescope Bibliography, telescope statistics are compiled at ob- and impact factors of articles from a database that lists all papers based on servatories, at which intervals, and by 18 journals regarding their distribution ESO data, as well as publication and whom.1 All respondents regularly gather among facilities, thus avoiding the bias citation statistics derived from this data- total and/or average numbers of their that typically can be noted in studies base have been documented in Leib- refereed publications, the majority also from individual observatories. undgut, Grothkopf and Treumann (2003) monitor unrefereed publications (e.g. and Grothkopf et al. (2005). The Tele- conference proceedings), either regularly scope Bibliography is publicly available or on request. Citation statistics of refer- The h-index via the web (http://www.eso.org/libraries/ eed publications are collected by all re- telbib.html) as well as through the “Select spondents, even though only half of them In order to overcome some of these dis- References In: ESO/Telescopes” filter does so on a regular basis, the remaining advantages, J. E. Hirsch of the University at the ADS (see Delmotte et al. 2005 for 50 % only on request. of California at San Diego suggested more details). a new and surprisingly simple measure As can be expected, observatories com- which he called the h-index (Hirsch In a recent paper, Hirsch (2005) proposed pile statistics tailored to their individual 2005). While the h-index originally was a new index to measure research output, needs, for instance number of publica- meant to be a measure for the research the so-called h-index. While originally tions and citations per instrument, pro- output of individual scientists, we ex- meant to analyse the productivity of indi- tend it here to observatory publication vidual researchers, we recently intro- 1 The following observatories responded to our statistics. In order to determine this value, duced it into telescope statistics (Groth- questionnaire (http://www.eso.org/libraries/ one needs a list of all relevant papers, kopf and Stevens-Rayburn 2007). Based telstats-questionnaire.html): CFHT, Chandra, ranked by decreasing citation counts; h Gemini, HST, Isaac Newton Group, Keck, NRAO, on h, we developed h(t) which reflects Subaru, XMM Newton. For more information, can then be found where the citation changes of the h-index in the course of contact Uta Grothkopf at [email protected]. count is at least as high as the rank. Thus,

62 The Messenger 128 – June 2007 the h-index combines measure of pro- 200 Figure 1: The h-index can be found ductivity (number of publications) and where the counted publication number equals the number of citations. impact (average number of citations per Neither a large number of publications paper) and is therefore more balanced with low citation rates (right edge of than most other measures used for bibli- 150 the x-axis) nor individual papers with ometric studies (Figure 1). extraordinarily high numbers of citations (upper edge of the y-axis) will alter h, therefore this value is more Instead of measuring the research output balanced than many other bibliometric measures. of individual researchers, the concept 100 can also be applied to entire observatories or specific observing facilities – Citations always bearing in mind the caveats described above. In a recent paper, we 50 introduced the h-index into telescope sta- h-index tistics by computing it for selected publication years of some major observatories (Grothkopf and Stevens-Rayburn 0 2007). 0 50 100 150 200 Publication number

The m-parameter Observatory Range of years Years since h m Table 1: Range of years of publica- It must be noted that, tempting as it may of publications first publication tions, number of years since first VLT 1999–2006 8 79 9.9 publication, as well as h and m of the be, comparing h alone among observ- observatories included in our study. atories (or researchers) does not lead to a Keck 1996–2005 11 113 10.3 meaningful result. Facilities that have Gemini 2000–2006 7 33 4.7 been operative for many years obviously Subaru 2000–2006 7 41 5.9 had much more time to produce publications and accumulate citations, hence their h-index can be expected to be con- h-index Figure 2: h-index for the VLT, Keck, siderably higher than that of younger 120 Gemini, and Subaru observatories as of April 2007. Note that h correlates facilities. Hirsch therefore introduced the with the number of years of operation. so-called m-parameter. For individual re- Hence, older observatories tend to 100 searchers, this value is computed by have higher h indices. dividing h by the numbers of years since publication of the first paper. Correspond- 80 ingly, when applied to observatories, h is divided by the number of years of operation; hence it reflects the various ‘life- 60 times’ of facilities.

40 Applying h and m to observatories 20 We present here h and m values for the VLT, Keck, Gemini and Subaru observatories. In order to compute h, we ob- 0 tained bibcodes of all papers pertaining VLT Keck Gemini Subaru to the observatories’ publication lists in 1999–2006 1996–2006 2000–2006 2000–2006 the following way: for the VLT, bibcodes are stored in the ESO Telescope Bibli- ography (http://www.eso.org/libraries/ translated into bibcodes. Papers using servatories in 2006. Citation counts for all telbib.html). References of Keck and Gemini data were found using the “Select publications were obtained from the ADS Subaru papers were retrieved from the References In” filter on the ADS main as of April 2007. web (Keck Science Bibliography at http:// search screen. These bibliographies in- www2.keck.hawaii.edu/library/keck_ clude only refereed papers. The respec- For each observatory, citation counts papers.html and Publishing Results from tive ranges of publication years are were then ranked in descending order, Subaru, http://www.naoj.org/Observing/ shown in Table 1. For uniformity, we end and h was computed. Figure 2 shows the Proposals/Publish/index.html) and were the range of publication years for all ob- h-indices of the respective observatories.

The Messenger 128 – June 2007 63 Astronomical News Grothkopf U. et al., Using the h-index to Explore the Scientific Impact of the VLT

We also computed the m-parameter by Parameter m Figure 3: Parameter m dividing h by the specific number of 12 of the observatories included in this study (as years since the first publication (see Ta- of April 2007). ble 1). Resulting values are given in Fig- ure 3. This brings the VLT and Keck 10 to the top of the list, and also the young facilities Gemini and Subaru perform well. 8

One should note that both h and m depend on the number of telescopes per fa- 6 cility. A facility like the VLT with four telescopes will produce more papers more quickly and hence the h-index will in- 4 crease faster, although it is not obvious exactly how much of an effect this is. 2 For a facility like the VLT, with telescopes becoming operational over some time, it will be difficult to quantify this effect in 0 detail. VLT Keck Gemini Subaru 1999–2006 1996–2006 2000–2006 2000–2006

The h-index versus time

Although the m-parameter reflects the total number of years of operation of h-index a facility, both h and m are integrated 120 values that don’t show how these values were achieved in the course of time. We have therefore further developed the 100 h-index to analyse its evolution, h(t). 80 To compute h(t), we obtained the citation history for each paper included in our study from the ADS. The citation history 60 shows how many citations a paper generated in a given year. For instance, a paper published in 2002 will generate x citations 40 in 2002, y citations in 2003, z citations in 2004, etc. In order to calculate h for a 20 year Y, we add up all citations up to the year Y, using the citation history of each paper. The papers are then listed in de- 0 creasing order, and the h-index for that 0 1 2 3 4 5 6 7 8 9 10 year Y is computed. Years after publication

Figure 4 shows h over time applied to the Figure 4: h(t) of Keck, VLT, Subaru and Gemini by Keck Subaru observatories in our study. Trends in- years after first publication (as of April 2007). VLT Gemini dicated by h and m are confirmed. Keck has always been performing extremely well, with a steeply increasing h-index right from the start. The VLT started well and has even improved during recent Gemini North and South as well as VLT Performance of the VLT instruments years. Both Subaru and Gemini are now UT1, 2, 3, and 4 all came online sequen- on their way up after a slightly slower tially, increasing the available obser- In order to investigate the specific perfor- start. ving time over the years. A future study mance of the VLT instruments, we ap- may investigate h(t) based on the actual plied h, m, and h(t) to them. We restrict In this study, all observatories are treated observing time of each observatory. this analysis to the VLT because instru- as entities. This does not accurately re- ment-level information for La Silla papers flect their early years. Keck I and II, has been systematically recorded only

64 The Messenger 128 – June 2007 starting in 2002. The results are presented Instrument h-index Years since m Number Total number Ratio in Table 2. Although the absolute num- first publication of papers of citations ber of papers and citations differ, the very VLT first instruments of the VLT (FORS1, FORS1 56 8 7.0 525 14 267 27.2 ISAAC, UVES, FORS2) have a compara- ISAAC 49 8 6.1 413 9 308 22.5 ble performance. As mentioned above, UVES 48 7 6.9 474 9 326 19.7 the number of years in operation is FORS2 46 7 6.6 342 9 006 26.3 an important factor. Young instruments NACO 22 5 4.4 111 1942 17.5 necessarily have a lower h-index. This FLAMES 14 4 3.5 67 877 13.1 can be partially compensated for by VIMOS 14 3 4.7 44 623 14.2 normalising the h-index by comparing VLTI 2 parameter m. VINCI 14 5 2.8 38 572 15.1 MIDI 7 3 2.3 19 226 11.9 As done for the observatories, a better glimpse of how the instruments are per- Table 2: Performance of VLT and VLTI instruments 2 Note that VINCI was offered to the forming can be achieved by measuring that have been operative for two or more years and community only from October 2002 produced at least ten papers. to October 2003. the h-index versus time. The results of h(t) as of April 2007 for VLT instruments are shown in Figure 5 relative to the year of the first paper of each instrument. In this graph, we included only VLT instruments that have been operative for two or more years and produced at least ten papers.

An obvious result is that the first-genera- h(t) tion VLT instruments (FORS1, UVES, 60 ISAAC, FORS2) are alive and kicking with no sign of changing their slopes. They clearly set a very high standard for future 50 instruments. 40 With respect to the young instruments, we can say that they are … young! Their h-indices are growing at a slow pace. Be- 30 sides this slow increase of the h-index for the young instruments, can we predict whether they will look like their older sib- 20 lings in future? UVES 10 FORS1 We see from Figure 5 that most of the FORS2 young instruments have a much harder ISAAC NACO time to take off than FORS1 and UVES, 0 VIMOS but they are not particularly different from 0 1 2 3 4 5 6 7 FLAMES the h(t) curves of FORS2 and ISAAC. Years after first publication But what is behind the plot shown in Fig- ure 5? Does the h(t) have a practical use Figure 5: h(t) of selected VLT instruments by years in judging instrument performance? after first publication (as of April 2007). Can it help observatories to decide whether a given instrument needs to be upgraded, improved or even decommis- sioned? The answer is not simple and the reader should take Figure 5 with caution. quality of the documentation and data- h. As time goes by the community gets reduction software (pipelines). These are used to the modes, pipeline, etc. At this As defined above, the h-index depends all factors that play a role in the way h(t) time the number of papers and citations on the number of papers and their ci- evolves. increases fast, and so does the h. Years tation counts. These two quantities are later, all possible (hot) applications start certainly instrument-dependent. For The intrinsic nature of the instrument it- to run out and the papers gather fewer example, detector sensitivity, spectral or self has an influence on its h(t). All in- citations. New (and hopefully better) in- spatial resolution, wavelength coverage, struments have a difficult start with a low struments come. At this point the h-index

The Messenger 128 – June 2007 65 Astronomical News Grothkopf U. et al., Using the h-index to Explore the Scientific Impact of the VLT

keeps growing, but at a much slower The bottom line is that we should take the Hirsch (2005) points out that the h-index pace. Thus the h(t) would have a curve- results presented in Figure 5 with cau- is prone to depend on the field of study of-growth shape (similar to those found in tion since none of the potential biases (Physics, Biology, etc.). This is true even chemical abundances studies). discussed above were taken into account within astronomy. For instance, astrono- and therefore the results presented here mers in the gamma-ray burst community In the case of instruments designed for are very preliminary. Having said that, have higher h-indices than their col- individual observations, papers can it might be interesting to peruse the ef- leagues in other areas, partly because of be based on a few observations and the fort of using the h-index to measure in- the importance of the field, but also be- full cycle (from proposal submission to strument impact and performance in a cause of the size of the collaborations paper acceptance) can be as short as deeper and more thoughtful study where and the rate of publications. one year. In contrast, papers presenting all biases are considered. results based on a large amount of If this effect is present with regard to in- data collected by survey-like instruments struments, it may indicate that a given (e.g., VIMOS and FLAMES) can take Conclusions instrument is flexible enough to produce years to be released. But when these pa- papers in a wide range of astronomical pers are finally published, the impact can The h-index is a simple, yet powerful in- fields. The numbers in Table 2 show that be immense. dicator that has some important ad- the first-generation VLT instruments have vantages compared to other bibliometric similar h-indices. They constitute an Another bias hidden behind the compu- methods: example of such versatility, since they are tation of h(t) has to do with the com- – it combines productivity and impact; used for observations ranging from the plexity of the new instruments, which in – it can be relatively easily determined Solar System to cosmological applica- some cases are aimed at tackling prob- using the ADS; tions. However, other biases influencing lems that require the use of cutting- – it is neither affected by a large number h(t) need to be carefully corrected before edge technology. Using a complex (new) of publications with few or no citations a detailed comparison is made. In this technology usually implies large over- (which usually suggests high productiv- sense, our results concerning the h-index heads. This is the case of AO instruments ity, but not necessarily high impact) nor for instruments are regarded as prelimi- and even more pronounced in the VLTI by extraordinarily high citations of only nary. observations whose complexity is of a a few papers (which inflates citation higher degree than that of any other VLT counts). instrument. Acknowledgements The h-index is therefore more balanced This research has made extensive use of NASA’s However, the h(t) can also be influenced than other measures if one bears in Astrophysics Data System Bibliographic Services. by circumstances not related to the in- mind the usual caveats intrinsic to biblio- strument at all. For instance, there is no metric comparisons. It is important to question that one of the strengths of note that h depends on the number of References the first suite of VLT instruments (FORS1, years of operation and therefore needs to Delmotte N. et al. 2005, The Messenger 119, 50 UVES, ISAAC and FORS2) is its versatil- be combined with the m-parameter Grothkopf U. et al. 2005, The Messenger 119, 45 ity, being used from Solar System to cos- in order to avoid biased interpretations. Grothkopf U. and Stevens-Rayburn S. 2007, in mological applications. In addition to “Library and Information Services in Astrono- my V”, eds. S. Ricketts, C. Birdie and E. Isaksson, this versatility, these instruments were fa- ASP Conference Series, astro-ph/0610274 voured by the fact that they were the Hirsch J. E. 2005, Proc. Nat. Acad. Sci. 102, 16569 only ones available to the community dur- Leibundgut B., Grothkopf U. and Treumann A. ing the first years of operation of the VLT. 2003, The Messenger 114, 46 Madrid J. P. and Macchetto F. D. 2007, in “Library Moreover, they were mounted almost ex- and Information Services in Astronomy V”, eds. clusively on each of the UTs. Nowadays, S. Ricketts, C. Birdie and E. Isaksson, ASP Con- the situation is very different. New instru- ference Series ments have to compete for UT time. Trimble V., Zaich P. and Bosler T. 2005, PASP 117, 111 For instance, on Kueyen UT2, the time is Trimble V., Zaich P. and Bosler T. 2006, PASP 118, shared between UVES, FORS1 and 651 FLAMES. Therefore, in order to be fair, the Trimble V. and Zaich P. 2006, PASP 118, 933 h(t) curve shown in Figure 5 has to be corrected by the effective fraction of time used by each instrument.

66 The Messenger 128 – June 2007 Astronomical News

Status of Women at ESO: a Pilot Study on ESO Staff Gender Distribution

Francesca Primas (ESO) b) ESO Faculty members, Fellows and a) ESO staff members Students; c) ESO Governing Bodies and Commit- Established members of ESO personnel Equal career opportunities require tees: Council, Observing Programmes are identified as International Staff Mem- working conditions that make it possi- Committee, Scientific and Technical bers (ISM), whereas Paid Associates (PA) ble to reconcile family needs and career Committee, Users Committee, Finance belong to the so-called non-established development. This article describes Committee; personnel. Typically about 7 to 10 PA are the goals and main findings of a pilot d) ESO Visitors; employed at ESO per year and these are investigation that has recently been e) invited speakers at ESO Lunch Talks included in the overall statistics of ESO carried out at ESO focusing on gender and the Munich Joint Astronomy Col- staff. balance issues. loquia. Figure 1 displays the fraction of female ESO staff over the past eight years. Dur- Over the past decades, several studies in The project and its outcomes ing the same time the ESO staff in- Europe (e.g. within the FP5-FP6 pro- creased from 239 ISM in 1999 to 329 ISM grammes) and the United States have Once all the data were gathered, we in 2006. This is also reflected in the considered gender distribution, and in compiled and analysed statistics on the recruitment statistics: ESO recruited particular the status of women, in dif- distribution of female and male employ- 33 women (17.7%) compared to 153 men ferent sciences. Gender equality and dual ees by various categories. The numbers (82.3 %) between 2000 and 2005. Al- careers are just two of the many aspects reported here cover all international staff though the number of women employed that have been closely scrutinised. In of ESO, i.e. at both the ESO Headquar- as ISM has increased from 44 to 59 astronomy, the Baltimore Charter and the ters in Garching and ESO Chile, with the over this period, it has clearly lagged Pasadena Recommendations are among latter including the Vitacura offices and behind the pace of male hiring. Among the main outcomes of these investiga- the La Silla Paranal observatory. Where the women hired, nearly half (16 or tions and provide guidelines on how the appropriate, we have split the analysis for 48.5 %) were scientists, 12 (36.4 %) were situation of women in astronomy could the two main ESO regions. In the follow- administrative staff and only 5 women be improved. Further, several working ing sections, we will briefly comment on (15.2 %) were engineers. When the break- groups have been established by interna- the results obtained for the different cate- down is done by ESO division, one finds tional scientific bodies. With ESO as a gories (a–e) that were scrutinised. that while the Office of the Director Gen- multi-cultural research organisation, it be- eral and Administration have a nearly came clear that a similar, systematic study even gender balance, the technical divi- of its current gender distribution was an sions have, in general, a very low frac- important goal to achieve. This article presents the first results of such a study. Figure 1: Yearly gender distribution of all ESO International Staff Members and Paid Associates (dark blue: male, light blue: female). The project and its goals

The “Status of Women at ESO” is a pro- 1999 ject that, as a start, aimed at evaluating the current gender distribution at ESO, 2000 thus providing a snapshot of the status of women at ESO. This task necessitated a systematic and impartial breakdown of 2001 the ESO organisational structure in terms of female versus male personnel mem- 2002 bers by division and rank over a given time period. The team was chaired by Francesca Primas and included Roland 2003 Block, Mark Casali, Nathalie Kastelyn, Rubina Kotak and Bruno Leibundgut. We 2004 focused on the period 1999–2006, which has witnessed a significant expansion 2005 in the number of staff members owing to the start of VLT operations, and on the following groups: 2006 a) ESO International Staff Members and Paid Associates by division and by 10 20 30 40 50 60 70 80 90 rank; %

The Messenger 128 – June 2007 67 Astronomical News Primas F., Status of Women at ESO: a Pilot Study on ESO Staff Gender Distribution

tion of women on their staff. The fraction Female | Male Fellows Students of female Paid Associates is slightly Full higher than that of ISM; this also holds in Garching 10 | 34 22 | 29 the more technically-oriented divisions. Chile 15 | 36 11 | 17 Associate All 25 | 70 33 | 46 When the grade is taken into account, the Garching (%) 22.7 | 77.3 43.1 | 56.9 difference becomes even more striking: Assistant Chile (%) 29.4 | 70.6 39.3 | 60.7 during the past three years, the percent- All (%) 26.3 | 73.7 41.8 | 58.2 age of female staff (ISM + PA) has re- Scientist mained rather stable, around 50–60% for salary grades 5–7, but only around 10% 10 20 30 for grades 8–11. This continues further total number into the management level (grades 12 and above) where at the moment there are Figure 2: Gender distribution (by total number) of Table 1: Total number and percentages of only two women. Women are clearly the three categories of ESO Faculty members, and ESO fellows and students (2000–2006). Scientist, in the year 2006 (dark blue: male, light blue: under-represented at the higher eche- female). lons, presumably corresponding to positions with a higher scientific and technical profile. It should be noted that the % Figure 3: Yearly gender distribution current Director General and one division 100 among the selected ESO fellows and applicants to the ESO Fellowship, head are women. By total numbers, ESO over the period 2000–2006 (for both has more than doubled the number of 80 Garching and Santiago). women in grades 8 to 11 (from 16 to 34), but the relative increase remains rather small (only 4%). 60 b) The ESO Faculty, Fellows and Students 40

The ESO Astronomer Charter defines the 20 roles of astronomers and their membership in the ESO Faculty. As of 2006, there Male Applicants Male Fellows are 17 women in the Faculty (to be com- 0 Female Applicants pared to 74 men), and their fraction has 2001 2002 2003 2004 2005 2006 Female Fellows increased fairly steadily over the past decade. The percentage of females among the years, which has stopped only in the past However, we note that the highest frac- selected fellows has been between year. The comparison of the gender distri- tion of female Faculty members is cur- 10 and 40 % over the past few years. The bution between Garching and Chile is rently at the Assistant Astronomer level, comparison with the distribution among shown in Figure 4. The fraction of female the entry level for junior staff. The Sci- the applicants (Figure 3) shows that the fellows has decreased dramatically in entist level (astronomers with reduced gender balance is reasonably maintained, Chile – by almost a factor of two since research time), also have a higher fraction i.e. there is no obvious discrimination 1999, while the distribution in Garching of women, as can be seen from Figure 2. against female candidates. has been between 25 and 40 % over the The global average, including all levels recorded period. Admittedly, very few (Full, Associate, Assistant and Scientist) is However, the years 2003 and 2004 show applications for ESO Fellowships in Chile 18.7% of women. that this is not universally true. In 2004, were received from female candidates in for instance, only one female fellow was 2003 and 2004, nevertheless the trends Complete statistics for ESO fellows and selected out of 34 female applicants! show that constant vigilance is required. students are available from the year 2000 Also, it should be noted that the fraction onwards for both ESO sites, including of female fellows is significantly higher The situation with the students is more the gender distribution among the appli- than for female members in the Faculty. positive. While there still appears to be a cants and the gender distribution in the Compared to the Assistant Astronomer majority of male applicants, the selection Fellowship and Studentship Selection level in the Faculty, the gender distribu- has consistently created a more balanced Committees (FSSC). Table 1 shows the tion is nearly the same. However, despite distribution so that ESO has a fairly high total number and percentages of all ESO the increased number of Fellowships fraction of female students (see Figure 5), Fellows and Students during the last offered in Chile for Paranal, we have ob- which is consistently above 30 % and seven years. served a steady decrease in the number often above 40 %. The fluctuations are of female applicants over the last few due to the short-term nature of student

68 The Messenger 128 – June 2007 1999 1999 All Garching Chile

2000 2000

2001 2001

2002 2002

2003 2003

2004 2004

2005 2005

2006 2006

10 20 30 40 50 60 70 10 20 30 40 50 60 % %

Figure 4: Percentage of female fellows in Garching, Figure 5: Percentage of female students in Garching, in Chile, and as a whole. in Chile, and as a whole.

contracts (two years in almost all cases, whereas in Garching, a realistic balance We noted that the more technically- with the International Max-Planck Re- of women on the committee has been oriented committees show a very low search School (IMPRS) contracts run- achieved. The fraction of women on this percentage of female representatives, ning for three years – currently there are committee is higher than the average whereas other committees (e.g. Finance six such positions at ESO Garching). The of the Faculty astronomers. Committee and the Users Committee) distribution between Garching and Chile have reached a very balanced gender is fairly balanced, with the large fluctua- distribution. However, every committee tions for Chile due to the small number of c) ESO Governing Bodies and External shows a positive trend, and the female students (ten positions). Committees representation is increasing, though at a slow pace. Overall, the situation with young re- ESO has one main governing body searchers at ESO has improved over the (Council) and several specialised commit- past few years. With the exception tees that have the task of making deci- d) ESO Visitors of 2003, the ratio of female students has sions and/or recommendations on spe- been consistently above 30 %. The cific matters. Since membership to these The ESO Scientific Visitor Programme number of applications from female stu- committees is selected in different ways aims to promote the scientific interaction dents is also steadily increasing. (not only among different committees, between ESO and its community and but even among different countries for to enhance ESO’s role as an astronomical We further investigated the composition the same committee), the numbers we centre of excellence. The programme of the selection committees for the fel- have gathered on this category are more is under the responsibility of the Head of lows and the students. In Chile, during complex to interpret. the Office for Science, who appoints the the past few years not a single woman members of the two Visitor Selection has been nominated to this committee, Committees (VSC, one in Garching and

The Messenger 128 – June 2007 69 Astronomical News Primas F., Status of Women at ESO: a Pilot Study on ESO Staff Gender Distribution

one in Vitacura) and their respective are also made based on suggestions Female | Male chairs. Applications to the ESO Scientific provided by other ESO staff members. LT JAC Visitor Programme can be submitted by 1999 3 | 49 1 | 32 any scientist with an interest in ESO ac- Together with MPA, MPE and the LMU- 2000 4 | 37 5 | 28 tivities and/or collaboration with ESO staff Sternwarte, ESO-Garching also co-orga- 2001 10 | 29 2 | 29 members. ESO can also make formal in- nises the Joint Astronomy Colloquia (JAC) 2002 5 | 29 4 | 26 vitations to scientists with a high scientific series, also held on a weekly basis. The 2003 11 | 28 1 | 27 profile. On average, ESO Garching is able JAC committee includes representatives 2004 6 | 19 5 | 30 to support between four and five visitors from all involved institutes. This is recog- 2005 5 | 23 4 | 33 per month. nised as the main scientific colloquium of the week. Table 2: Gender distribution among the invited From the data we have been able to speakers to Lunch Talks (LT) and the Joint Astron- omy Colloquium (JAC). collect, i.e. the gender distribution of the Table 2 shows that gender distribution in applicants, as well as of the approved the Lunch Talk (LT) series is clearly and invited visitors over the past eight more balanced than the one among JAC stant for the past eight years. The women years (1999–2006) at ESO Garching, there speakers, but there is clearly room for employed at ESO are preferentially in is clearly no discrimination in the approval improvement here as well. The numbers lower grades with very few women in sen- of the applications – ESO Garching is in the table are yet another reflection of ior positions. In other words, the signifi- usually able to approve almost all applica- the fact that there are more junior than cant increase in the number of newly- tions. Nevertheless, we note that despite senior female astronomers. Considering hired staff members required by the start the fact that the ESO visitor programme the higher relevance of the JAC series, of VLT operations has not resulted in is open to everybody, the number of the very low number of female speakers a corresponding increased fraction of fe- female applicants represents a very small is discouraging. The JAC committee is male staff (at any level). percentage; the reason for which is not currently chaired by a woman and it will easy to uncover. One possibility is that be worthwhile to monitor the selection 2. The conspicuous lack of senior female for female astronomers with family com- of speakers in the coming years. astronomers is striking. The fraction mitments, it is notoriously difficult to take of women in the Assistant and Associate leave of absence from their home insti- levels is encouraging, although not yet tute. However, there is clearly room for Present and future satisfactory, and it reflects the recent em- improvement, especially for the targeted ployment history. The Assistant Astron- high-profile astronomers: here, the num- All the numbers collected so far and dis- omer level is the entry level for Faculty as- bers are extremely small (only three wom- cussed in this report have been taken tronomers at ESO and these are the en in the last few years), and ESO should at face value, i.e. they represent snapshot junior members. It seems important to make a special effort to attract senior views of the gender distribution among assess what support is required to have women for extended visits. ESO staff and various ESO governing these women succeed both in their re- bodies and committees, during the last search and at ESO, as well as to increase We note that the composition of the VSC- few years. No attempt has yet been made their number further and ensure that the Santiago at the beginning of this year to compare these numbers to, for in- fraction does not decline with increasing included one female and seven male as- stance, the number of applicants and seniority. In a few years these numbers tronomers, which is identical to the 2006 eventually short-listed candidates for any should be critically assessed and the rea- situation of the VSC-Garching. given staff position. This type of com- sons for possible changes examined. parison was readily available for the Fel- lows and Students only, as discussed 3. The gender distribution among the e) Invited speakers to Joint Astronomy above. Due to this incompleteness, it is ESO Fellows and Students is in general Colloquia and ESO seminars difficult to properly interpret these num- higher than for the staff and the Faculty. bers and draw firm conclusions. In what The selection of the Fellows and Students ESO is a very lively scientific environment, follows, we attempt to flag the most im- does not show clear discrimination, but where many scientific talks are organ- portant outcomes of this pilot project and constant awareness in the selection ised on a weekly basis, both in Garching possible future actions that ESO is con- process is still required. The low female and in Santiago. ESO-Garching has its sidering. selection rates in 2003 and 2004 are a own Lunch Talk (LT) series, organised by warning not to neglect this issue. an appointed team of ESO-Garching 1. Concerning ESO Staff, we have estab- staff (usually two to three members, who lished that the gender distribution is 4. For the Scientific Visitor Programme, it change every two to three years). This not very balanced (18 % female versus would probably be helpful to assemble committee has the task of running a full 82 % male). The balance is far from being a list of high-profile female scientists to schedule of weekly talks, by inviting satisfactory, especially in the more tech- become the target of official invitations to speakers who cover a broad range of sci- nically-oriented divisions, where very few visit ESO. If no improvement is seen over entific activities and interests. Invitations women are employed. It is disappointing a given amount of time, then one should that this distribution has remained con- try to understand the main reasons that

70 The Messenger 128 – June 2007 make women decline the invitations (fam- has adopted, and will continue to adopt a prompt support in gathering some of the numbers ily organisational issues, busy profession- series of measures that aim to contribute presented in this document: Francky Rombout, Christina Stoffer, Pamela Bristow, Karin Hansen, al schedules, etc.). towards an effective personnel policy. Sandro D’Odorico, Fernando Comerón, Andreas Some changes to the regulations to fur- Kaufer and Markus Kissler-Patig. 5. For the Lunch Talks, but especially for ther help women and family members the JAC series, a similar list of high-profile working at ESO have recently been im- References female scientists could be useful in order plemented (e.g. on-site daycare, more to significantly increase the number of flexibility on maternity leave, as well as The following list of publications includes recent female speakers. It is well known that the part-time solutions) and discussions of results from studies similar to ours (some of which percentage of female invited speakers at several more are under way with the ap- were mentioned in the text) as well as some suggestions for further reading. These references can be any scientific conference remains low. propriate committees. found in the form of articles or web sites. The list The International Astronomical Union, for does not intend to be exhaustive, rather a starting instance, is now checking, for each sym- Independently of these important im- point for the interested reader. posium they sponsor, the gender and provements, and despite the fact that the The Baltimore Charter for Women in Astronomy national distribution of the scientific orga- current situation at ESO closely follows (http://www.stsci.edu/stsci/meetings/WiA/ 1 nising committee and of the invited the numbers of the other EIROforum in- BaltoCharter.html) speakers, requiring the organisers to pro- stitutes (CERN, ESA, ILL, EMBL, ESFR, The Pasadena Recommendations (http://www.aas. pose alternative names if the gender EFDA), ESO needs to better understand org/~cswa/Equity_Now_Pasadena.pdf) The European Commission reviews on Gender balance is not satisfactory. ESO might why the number of female staff has not Equality (http://ec.europa.eu/employment_social/ want to follow a similar philosophy for its increased over the past few years. Is ESO gender_equality/index_en.html) and their own series of symposia and workshops. not attractive enough for female astrono- publications, including the most recent (2007) mers and engineers? Are the ESO work- report (http://ec.europa.eu/employment_social/ emplweb/gender_equality/publications_en.cfm) The importance of this study is that it ing conditions not suitable for female staff A Study on the Status of Women Faculty in Science provides a baseline for future comparison to simultaneously cope with professional at MIT (1999 and its 2002 update) (http://web.mit. and should be used as a reference for career and family commitments? Con- edu/faculty/reports/pdf/sos.pdf) future studies regarding the status of stant monitoring and increasing aware- Review of the Status of Women at STScI (2002) (http://www.aura-astronomy.org/nv/womensRe- women at ESO. Once ALMA will have ness will hopefully lead to improvements. port.pdf) and the AURA (Association of Universi- started early operations and ESO may be ties for Research in Astronomy) response to the involved in the development of its next report (http://www.aura-astronomy.org/nv/ large facility, it may make sense to repeat Acknowledgements response.pdf) The AIP (American Institute of Physics) Report on this study. The investigating team would like to warmly thank “Women in Physics and Astronomy, 2005” (http:// the following people for their invaluable help and www.aip.org/statistics/trends/reports/women05. Equal career opportunities require work- pdf) ing conditions that make it possible to re- The IAU (International Astronomical Union) Working 1 Group of Women in Astronomy (http://astronomy. concile family needs and career develop- EIROforum is a partnership of Europe’s seven largest intergovernmental research organisations, swin.edu.au/IAU-WIAWG/) ment. Being an international organisation which includes: the European Organization for The AAS (American Astronomical Society) Commit- adds extra responsibility to the employer: Nuclear Research (CERN); the European Fusion tee on the Status of Women in Astronomy (http:// it is usually more difficult for expatriates Development Agreement (EFDA); the European www.aas.org/~cswa/) The IUPAP (International Union of Pure and Applied to fall back on childcare facilities or rely Molecular Biology Laboratory (EMBL); the Euro- pean Space Agency (ESA); the European Synchro- Physics) Working Group on Women in Physics on family help in the country of employ- tron Radiation Facility (ESFR); the Institute Laue (http://www.iupap.org/wg/wip/index.html) ment other than the home country. ESO Langevin (ILL); and ESO.

At the control station of Melipal (UT3).

The Messenger 128 – June 2007 71 Astronomical News

Report on the International Workshop on Observing Planetary Systems held at ESO, Vitacura, Chile, 5–8 March 2007

Michael Sterzik, Christophe Dumas ness of the field for the next generation of of highest relevance for the massive (ESO) researchers. Each of the four sessions follow-up of planetary transit candidates was organised around three presenta- (Queloz). tions by invited speakers, each of 45 min, Motivation all contributing to the discussion from a Direct imaging of extrasolar planets is a complementary perspective of Solar Sys- key science driver for many future ground- Nowadays, the ESO premises in Vitacura tem and extraplanetary sciences. The and space-based instrument develop- host more than 80 PhD students, fel- addition of contributed talks and a large ments. A few extrasolar giant planets lows and astronomers, and represent the number of posters deepened our under- (EGPs) around nearby young stars are research centre for the scientific staff de- standing of each subject. All available already in reach of current adaptive- ployed at the different observatory sites time-slots were intensively used for lively optics assisted NIR companion search in Chile. Several topical working groups and open discussions and some poster programmes, and a leap of the astro- help locally to actively promote and foster pop-up sessions were organised at the physical understanding of EGPs is ex- joint research initiatives among ESO sci- end of each day. pected with the next-generation high entists. One example is the “Planetary contrast imagers, like SPHERE (Mouillet). Sciences Research Group” at ESO Chile Astrochemistry provides another im- (http://www.sc.eso.org/santiago/science/ Scientific highlights portant link from our own Solar System PlanetaryGroup), which seeks to under- to other planetary systems. Deuterium-to- stand the formation of planetary systems A few subjectively selected highlights hydrogen ratios appear remarkably simi- at large and the place occupied by our may demonstrate the scientific ideas and lar in comets and in the interstellar me- own Solar System. Group members are prospects presented during this work- dium (Kamp). Comets, as messengers actively involved in observation-oriented shop. from the early Solar System, may reveal programmes making use of ESO facilities the answer to questions like, why is the to carry out front-line research ranging The physical, chemical, and morphologi- Earth wet and alive? (Mumma). Transiting from discoveries of new brown dwarfs cal evolution of circumstellar discs from (eclipsing) planets play a key role in un- and exoplanets, to the study of primitive gas-dominated rotating optically thick derstanding their physics and chemistry. Solar System bodies. structures towards thin planetesimal discs Atmospheres of hot Jupiters can be stud- is a key to understand the formation of ied in detail by transmission spectros- Encouraged by the fruitful interdiscipli- planetary systems in general, and our own copy, while mass-radius-composition nary research approach of our own Solar System in particular. Disc models relations allow the interior of super-earth group, we proposed to gather both com- can be best constrained by applying a planets to be probed: the era of communities of Solar System and extra- combination of modern observing tech- parative exoplanetology has just started planetary system scientists and organise niques, utilising the highest spatial resolu- (Charbonneau)! the international workshop “Observing tion imaging in the optical and NIR in Planetary Systems”. The main idea was to scattered light, polarimetry and SED de- The search for signatures of life on exo- explore the synergy between these two termination. Dust settling, i.e. the vertical planets by the detection of atmospheric communities and confront them with four segregation of particles with different and surface biomarkers is a far-reaching key topics: from Discs to Planets; Search masses and sizes can now be directly goal of future, ambitious, space-based for Planets; Planetary Chemistry; Towards probed (Menard). The dynamical history missions. Both ESA and NASA are active- other Earths. In order to establish such of our own Solar System, as recon- ly promoting missions not only to detect, meetings as part of our research culture, structed by sophisticated numerical but also to characterise, the physical we selected the venue to be in our refur- N‑body integration, teaches us charac- conditions of terrestrial planets (Fridlund, bished, large, conference room in Vita- teristic differences and/or similarities with Lawson). Today, Earth is still the only cura, equipped with state-of-the-art au- known extrasolar systems, such as why known planet that hosts life, and it can dio-visual facilities. does our Solar System not have a hot serve as a template to discuss potential Jupiter? The most likely reason is the res- biosignatures in other habitable worlds. The response from the community was onant hierarchical configuration of our The search for life beyond our Solar Sys- overwhelming. While our original plans four gas giants. Late heavy bombard- tem may soon become a reality – exciting were to limit attendance to 60–80 partici- ment, a cataclysmic episode of planetesi- times are ahead (Kaltenegger)! pants, nearly 120 scientists participated mal infall on terrestrial planets, requires a in the workshop, many of them worldwide large reservoir of planetesimals and ap- Contributed talks and posters presented recognised leaders in their field: about pears therefore compatible with the dust the latest results from ground-based and half of the participants were from Euro- excesses observed in debris discs space-based (e.g. Spitzer) observatories pean countries, 20 % from the USA, 20 % (Morbidelli). Accuracy limits of radial ve- in the search for exoplanets and the from Chile, 5 % from other South Ameri- locity searches for exoplanets are con- study of planetary-system formation, in- can countries, and a few researchers tinuously improving, and the physical cluding our own. The prospects for future joined us from Japan and Australia. A limits have still not been reached (con- ground-based interferometric, radial- healthy number of students (~ 30 % of the trary to what was thought ten years ago). velocity and high-contrast imaging instru- participants) demonstrated the attractive- Precision RV studies will continue to be ments in the field of exoplanet search

72 The Messenger 128 – June 2007 Participants at the workshop on “Observing Stellar Systems” photographed in the garden at ESO Vitacura. well invested in making an attractive programme, and supporting some participants to enable their visit in Chile. In total about 40 % of the participants received some financial aid; half were students, half researchers, and all students had their registration fees waived.

We would like to thank ESO for allocating the financial support for this workshop, and the Pontificia Universidad Católica de Chile its co-sponsoring. Also, we would like to thank all people who made this workshop possible, in particular Maria- Eugenia Gomez, our librarian who acted were presented, while several contribu- stead, all contributions, both oral and as workshop secretary, the ESO-Chile tions highlighted the importance of com- poster, were made available for download administration for the logistical sup- bining in situ spacecraft missions of immediately after the workshop from the port received, and the students from the the planets and small bodies of our Solar conference website (http://www.sc.eso. Universidad Católica de Chile, who System with ground-based supporting org/santiago/science/OPSWorkshop) – helped during the four days of this work- observations (Cassini/Titan, Rosetta/ given the consent of the authors. This de- shop, notably at the time of the registra- Churyumov-Gerasimenko, Mars space cision was based on our belief that pro- tion. The flawless local organisation, missions). Although we are still lacking viding instant access to the research the highly praised coffee breaks (includ- evidence for the presence of life outside highlights presented during this meeting ing delicious appetisers), joint cocktails the Earth, the discussions generated dur- was more useful than waiting for printed and conference dinner all contributed to ing this four-day workshop deepened proceedings in a competitive field like this a warm and friendly atmosphere during our belief that the search for signatures of one, where results are rapidly evolving the workshop, remembered by all partici- life in our own Solar System will provide and will be published in refereed journals. pants. strong guidance to the future exploration The idea to provide near-instantaneous of exoplanetary systems. access to the material discussed in this While meetings of this quality and size workshop was developed even further by take place naturally in many research providing, experimentally, a live-stream institutes in Europe and North America, Summary webcast during the conference (video- ESO Vitacura largely lacks this experi- streams are also available for download ence and we are looking forward to future On purpose we opted not to publish on the conference website). We also be- workshops of this kind organised within printed proceedings of this workshop. In- lieve that the costs saved have been our premises.

The Re-launch of the ESO Web

Rein Warmels, Gabriele Zech (ESO) The ESO Web plays an integral and in- and is critical for coordination and disse- dispensable role in the process of doing mination of information, both internal and science with ESO’s observing and external to ESO, in particular in the area Recently, the ESO Web went through a archive facilities. It provides an effective of science and archive operations. major revision and was re-launched and adaptive medium for exchanging with a new Look and Feel and new navi- information, documents and images be- The ESO Web started its service in 1994. gation tools. This article gives an over- tween scientists, engineers, the media Since then it has expanded rapidly, both view of why and how the ESO Web has and the general public. Furthermore, it in the amount of information and serv- changed. provides various services to the commu- ices that are provided as well as in terms nity of users of ESO’s observing facilities of access rates. Currently, the statistics

The Messenger 128 – June 2007 73 Astronomical News Warmels R. and Zech G., The Re-launch of the ESO Web

show that on average 100 000 pages are adapting to the fact that the large majori- observing facilities and the astronomy viewed per month, representing a data ty of web users are from the public do- programmes using these facilities, con- transfer volume of the order of 20 Gbytes. main. Other objectives for making a new tact and travel information, ESO’s public ESO web included: affairs’ activities (including information for In spite of the information and services – improve the appearance, i.e. give the press and media), the new ESO Public that have been added to the ESO Web ESO Web a more modern ‘Look and Image Archive (Figure 2), as well as infor- continuously over the past years, its struc- Feel’; mation for ESO’s industrial partners and ture has not been adapted; the ‘Look – improve the navigation and provide about current vacancies. and Feel’ still reflected the predominantly more functionality; science-oriented approach and usage – improve page content, in particular The Science area (Science Users Infor- of the ESO Web in the mid-nineties. Since make sure that the content is up-to- mation) provides information and serv- then ESO’s observing facilities have been date. Remove old and outdated pages ices for professional astronomers cover- greatly enlarged: Paranal has become and information; ing ESO’s observing and archive facilities. fully operational, the concept of service – restructure the site to serve the differ- Examples are instrument information, observing was introduced to maximise ent user groups more efficiently; Phase I proposal submission, policies the operational efficiency and scientific – find and assign responsible persons for and procedures, service observing and productivity, and the ESO/ECF Science well-defined areas. data processing. Also information about Archive and Virtual Observatory archival science activities, science meetings, research facilities are being offered. In The new ESO Web has three major user the library, and publications can be found addition, over the past years a large num- areas: here. In the Science area pages at the ber of science collaborations and pro- 1. Public. This area is intended for the top navigation levels have been imple- jects, and public outreach programmes, general public, press and media, (po- mented with the new Look and Feel. were initiated. tential) industrial partners and people Lower level pages that are still in the old interested in working at ESO. The area format will be converted later. New information and services were is completely new, partially based on added arbitrarily to the old structure and existing information, but also with new Most of the information in the Intranet could not easily be integrated into the content. area is still in the old layout. It is intended existing navigation. Consequently, the 2. Science Users. The area is intended for that also in this area the new Look and ESO Web became increasingly complex, professional astronomers who are Feel will be implemented. barely maintainable and it became in- doing, or are planning to do, research creasingly difficult to store new informa- using ESO facilities. The new structure of the ESO Web is re- tion and services that would be easy to 3. Intranet. This area is for ESO Staff only. flected in the navigation bar to the left find and use. and the breadcrumb navigation at the top The new Look and Feel has been imple- of each page. The main areas of Public, In particular, the start of science opera- mented throughout the whole Public Science, and Intranet can be accessed tions of the VLT and its scientific re- area (ESO for the Public – see Figure 1) via separate buttons. Each area has its sults triggered a substantial increase in and includes information of general inter- own navigation menu that helps the user the awareness of ESO amongst the est. Examples are descriptions of ESO’s to easily find the information or service of public and the media and, consequently, interest. a noticeable change of user profile of the ESO Web. Meanwhile, nearly every private citizen has Internet access and expects that information can be found easily. To support this new aspect of In- ternet usage, which includes the requirement to present ESO’s activities to the general public, ESO’s Web presence had clearly to be revised and improved.

During the past months ESO’s Public Af- fairs Department (PAD) has been working on a new ESO Web. This work was done in collaboration with the IT Department. It was guided by the conclusions and recommendations of an internal working group, taking into account that over time the overall user profile has changed significantly. In this sense ESO is follow- Figure 1: The new ing other organisations, such as CERN, in ESO home page (Public Area).

74 The Messenger 128 – June 2007 The new ESO Web can be reached via Figure 2: The new ESO ESO’s standard URL: http://www.eso.org/, Public Image Archive. The page shows which brings the user to the Public portal. the overview of galaxy The Science Users and Intranet naviga- images currently avail- tion buttons bring users to the Science able. and Intranet portals respectively; these pages can also be bookmarked as start pages for the ESO Web.

In the current implementation the ESO Web still consists of many single web pages that use a common style and navigation. In the near future it is planned to move to a database-based Content Man- agement System. This will substantially improve maintainability of the site and will serve all web users with the most current information and a common Look and Feel.

Fellows at ESO

Maria Messineo port astronomer on Paranal. At Paranal I mostly work with the UT4-Yepun tele- I have been an ESO fellow since Septem- scope and operate both of the infrared ber 2004. I am interested in studying detectors: NACO and SINFONI. I really the morphology and evolution of the enjoy observing and supporting visiting Milky Way. Although it is well established astronomers during their runs, and each that our Galaxy is a barred spiral galaxy, time I learn a lot, both scientifically and the properties of each Galactic compo- technically, and receive valuable feed- nent – Disc, Halo, Bulge, central Bar – are back concerning my research. still poorly constrained. It is difficult to properly map the large-scale morphology Currently I am investigating the spatial of the Milky Way, mainly because we distribution of young stellar clusters in the observe it from inside the Disc and be- Milky Way using SINFONI data. The aim cause light absorption from interstellar of this project is to better understand the dust strongly hampers an unbiased view current star formation in our Galaxy, as of its stellar content. well as the locations of spiral arms. From Maria Messineo next July I will continue to work on this Like Archimedes, I grew up on the an- topic at the Rochester Institute of Tech- cient and wonderful island of Sicily. I During my Ph.D. I went observing with nology (USA): more science to carry out started to study astronomy at the Univer- the IRAM 30-m telescope in Spain sev- and a new world to discover! sity of Bologna where I graduated in the eral times as well as with the Heinrich spring of the 1997 with a Master’s Thesis Hertz Telescope in Arizona, with the ESO on Galactic globular stellar clusters. I 3.6-m and the CTIO 4-m telescopes in did my Ph.D. research in Leiden studying Chile. I always enjoyed my time at the the distribution of stars in the inner re- telescopes very much, and so it was ob- gions of our Galaxy as a direct probe of vious that when I joined ESO I would the gravitational potential. perform my functional work as a sup-

The Messenger 128 – June 2007 75 Astronomical News

Laura Parker galaxy evolution and fundamental cosmology. I am enjoying working in such a I arrived at ESO in late 2005 after com- stimulating scientific atmosphere, par- pleting my Ph.D. work at the University of ticularly the many seminars and the lively Waterloo in Canada. I am generally inter- discussions at morning coffee. The diver- ested in all questions related to the for- sity of research carried out by ESO mation and evolution of galaxies, as well researchers is something hard to match as understanding the fundamental cos- anywhere else. For my functional work I mological parameters which govern the joined the ESO survey team which over- evolution of the Universe. My research sees the planning and execution of public focusses on the link between luminous surveys (for the VST and VISTA). My re- galaxies and the dark-matter halos in search makes use of large imaging sur- which they reside. I study the amount and veys so this project is a perfect fit to my distribution of dark matter using weak interests. gravitational lensing, and to date my work has focussed mainly on galaxy and gal- I will be sad to leave Garching (and the axy group sized structures. biergartens) behind but I am excited Laura Parker about moving onto the next chapter in my Since arriving in Garching I have contin- career. I will join the faculty at McMaster ued my work in weak lensing – which is a University as an assistant professor in leading technique for understanding both late 2007.

Personnel Movements

Arrivals (1 April–30 June 2007) Departures (1 April–30 June 2007) Europe Europe Arbogast, Dina (F) Secretary/Assistant Bedin, Luigi (I) Fellow Austin-May, Samantha (GB) Assistant Head of Foellmi, Cedric (CH) Fellow Personnel Department Huster, Gotthard (D) Mechanical Engineer Cikic, Zoran (F) Senior Contract Officer Sadibekova, Tatyana (UZ) Student Clare, Richard (GB) Physicist Vasisht, Gautam (IND) Software Engineer Guerlet, Thibaut (F) Student Haimerl, Andreas (D) Electronics Technician Hussain, Gaitee (GB) Astronomer Laaksonen, Milla (FIN) Administrative Assistant Lombardi, Gianluca (I) Student Mazzoleni, Ruben (I) Appied Scientist Ngoumou Yewondo, Judith Savina (D) Student Penker, Thomas (D) Assistant Facility Management Tanaka, Masayuki (J) Fellow Testi, Leonardo (I) ALMA European Project Scientist Chile Chile Ederoclite, Alessandro (I) Operations Astronomer Aguilera, Hugo Freddy (RCH) Accounting Officer Elliott, David (GB) Student Eschwey, Jörg (D) Civil Engineer Haguenauer, Pierre (F) VLTI System Engineer Fischman, Nicolas (RCH) Head of Contract and Procurement Francois, Patrick (RCH) Operations Astronomer Garcia, Enrique (RCH) Electronics Technician Hartung, Markus (A) Fellow Jehin, Emmanuel (B) Operations Astronomer Mella, Juan Alberto (RCH) Safety Engineer Shen, Tzu Chiang (CN) Software Engineer Soto, Ruben (RCH) Software Engineer Vannier, Martin (F) Fellow Zagal, Juan (RCH) Software Engineer

76 The Messenger 128 – June 2007 ESO

European Organisation for Astronomical Research in the Southern Hemisphere

ESO Fellowship Programme 2007/2008

The European Organisation for Astronomical Research in the We offer an attractive remuneration package including a competitive Southern Hemisphere awards several postdoctoral fellowships each salary (tax-free), comprehensive social benefits, and provide finan- year. The goal of these fellowships is to offer young scientists op- cial support for relocating families. Furthermore, an expatriation portunities and facilities to enhance their research programmes by allowance as well as some other allowances may be added. The facilitating close contact between young astronomers and the outline of the terms of service for Fellows (http://www.eso.org/gen- activities and staff at one of the world’s foremost observatories. fac/adm/pers/fellows.html) provides some more details on employment conditions/benefits. With ALMA becoming operational in a few years, ESO offers ALMA Fellowships to complement its regular fellowship programme. Candidates will be notified of the results of the selection process Applications by young astronomers with expertise in mm/sub-mm between December 2007 and February 2008. Fellowships begin astronomy are encouraged. between April and October of the year in which they are awarded. Selected fellows can join ESO only after having completed their In Garching, the fellowships start with an initial contract of one year doctorate. followed by a two-year extension (three years total). The fellows spend up to 25 % of their time on support or development activities The closing date for applications is 15 October 2007. in the area of instrumentation, operations support, archive/virtual observatory, VLTI, ALMA, ELT, public affairs or science operations at Please apply by filling the web form available at: https://jobs.eso.org the Observatory in Chile. In Chile, the fellowships are granted for You can provide the following information by uploading the files one year initially with an extension of three additional years (four directly through the web application form: years total). During the first three years, the fellows are assigned to – your Curriculum Vitae including a (refereed) publication list one of the operation groups on Paranal, La Silla or APEX/ALMA. – your proposed research plan (maximum two pages) Fellows contribute to the operations at a level of 80 nights per year – a brief outline of your technical/observational experience at the Observatory and 35 days per year at the Santiago Office. Dur- (maximum one page) ing the fourth year there is no functional work and several options are provided. The fellow may be hosted by a Chilean institution (and In addition three letters of reference from persons familiar with your will thus have access to all telescopes in Chile via the Chilean ob- scientific work should be sent to ESO electronically (vacancy@eso. serving time). Alternatively, she/he may choose to spend the fourth org) before the application deadline. Preferred format for submis- year either at ESO’s Astronomy Centre in Santiago, or at the ESO sions is pdf. Headquarters in Garching, or at any institute of astronomy/astrophysics in an ESO member state. Please also read our list of FAQs at http://www.eso.org/~mrejkuba/ fellows_FAQ.html regarding fellowship applications. All fellows have ample opportunities for scientific collaboration within ESO, both in Garching and Santiago. For more information about Questions not answered by the above FAQ page can be sent to: ESO’s astronomical research activities please consult http://www. Marina Rejkuba, Tel +498932006-453, Fax +498932006-480, eso.org/sci. A list of current ESO staff and fellows and their research e-mail: [email protected] interests can be found at http://www.eso.org/sci/activities/personnel. Additionally, the ESO Headquarters in Munich, Germany hosts the Although recruitment preference will be given to nationals of ESO Space Telescope – European Coordinating Facility, and is situated in member states (members are: Belgium, Denmark, Finland, France, the immediate neighbourhood of the Max-Planck Institutes for As- Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzer- trophysics and for Extraterrestrial Physics and only a few kilometres land, the Czech Republic and United Kindom) no nationality is in away from the Observatory of the Ludwig-Maximilian University. principle excluded. In Chile, fellows have the opportunity to collaborate with the rapidly expanding Chilean astronomical community in a growing partner- The post is equally open to suitably qualified male and female ship. applicants.

ESO. Astronomy made in Europe

The Messenger 128 – June 2007 77 Astronomical News

Announcement of ALMA Community Meeting Surveys for ALMA Workshop

3–4 September 2007, Garching, Germany 5–6 September 2007, Garching, Germany

Now ALMA has entered its main con- from future ALMA users. Also, a sample and the Planck mission will also be oper- struction phase, ESO and RadioNet are of exciting recent scientific results, rele- ational, and provide unprecedented far- organising two back-to-back meetings in vant to ALMA and the opportunities infrared survey capabilities. The progress Garching, aimed at the European astro- afforded by ALMA in its Early Science in wide-field near-IR detectors on dedi- nomical community. phase, will be presented. cated telescopes such as VISTA will also provide a major new data set for ALMA The ALMA Community Meeting will start The “Surveys for ALMA” workshop will follow-up observations. The aim of this at 14:00 on Monday 3 September 2007 directly follow the Community Meeting, one-and-a-half day meeting is to coordi- and end in the late afternoon of Tuesday starting on Wednesday 5 September, and nate the planning of these preparatory 4 September. The aim of this one-and-a- end at lunchtime on Thursday 6 Septem- surveys for ALMA, and to solicit feedback half day meeting is to keep the European ber. The rationale behind this meeting is from the community in the planning of the astronomical community informed about as follows. While ALMA is being con- early science follow-up with ALMA from ALMA progress since the last ALMA structed in Chile, several ground-based these surveys. The potential for deep Community Day in September 2004. The millimetre and submillimetre observato- legacy type surveys with the completed meeting will provide information about ries worldwide are being upgraded and ALMA array in 2012 will also be briefly the project status, and additional reports are now coming online. The excellent discussed. on other ALMA activities such as the wide-field survey capabilities of large bo- status of software. The definition of the lometer arrays such as LABOCA and If you would like to register for one or ALMA Operations Plan and the organisa- SCUBA-2 on single-dish sub-millimetre both of these meetings, or would like to tion of the European ALMA Regional telescopes such as APEX and the JCMT, obtain further information, please visit Centre (ARC) has considerably advanced and the upgraded (sub-)millimetre arrays, http://www.eso.org/projects/alma/ during the last year. Plans for ALMA op- such as IRAM, allow prospective ALMA science/meetings/gar-sep07/ eration and for the organisation of the users to develop ambitious science ARC network in Europe will be presented projects and prepare for the use of ALMA. The registration deadline is 13 July 2007. and discussed at the Community Meet- During the first years of operation of ing, with the aim of obtaining feedback ALMA, the Herschel Space Observatory

Announcement of the MPA/ESO/MPE/USM 2007 Joint Astronomy Conference on Gas Accretion and Star Formation in Galaxies

10–14 September 2007, Garching, Germany

This meeting will focus on the following 4. Theoretical models and empirical con- Scientific Advisory Committee: question: how does gas get into galaxies straints on the global efficiency Jacqueline Bergeron (IAP), Andi Burkert and what are the processes that regu- with which gas is converted into stars (MPIA), Chris Carilli (NRAO), Francoise late the rate at which the gas then turns in galaxies Combes (ObsPM), Andy Fabian (IoA), into stars? The conference will bring 5. Gas inflow mechanisms Reinhard Genzel (MPE), Ortwin Gerhard together both theoreticians and observa- 6. Feedback processes in galaxies (MPE), Tim Heckman (JHU), Guinevere tional astronomers working at different 7. The nature of the Warm/Hot Intergal- Kauffmann (MPA), Rob Kennicutt (IoA), wavelengths, using different techniques, actic Medium (WHIM). Does gas cool Eliot Quataert (University of California, both at low and at high redshifts. The from the hot phase? Insights from Berkeley), Piero Rosati (ESO), Renzo topics to be addressed in the conference XMM/Chandra Sancisi (INAF), Ken Sembach (STScI), are: 8. Physical constraints on gas in the Mike Shull (University of Colorado, 1. H i observations of gas in and around vicinity of galaxies from quasar ab- Boulder), Ian Smail (Durham), Jonathan nearby galaxies sorption lines Tan (ETH, Zurich) 2. The relation between atomic and 9. Star formation in high-redshift galaxies molecular gas Further information can be found at 3. Insights into the gas-star cycle in http://www.mpa-garching.mpg.de/ galaxies from new panchromatic data ~gassf07/ sets

78 The Messenger 128 – June 2007 A field of ‘White Penitents’ – ice sculpted by solar radiation – at the high altitude of the

ALMA site at Llano de Chajnantor. Photo: H. H. Heyer, ESO ESO is the European Organisation for Contents Astronomical Research in the Southern Hemisphere. Whilst the Headquarters The Organisation (comprising the scientific, technical and C. Cesarsky – The Czech Republic Joins ESO 2 administrative centre of the organisa- J. Palousˇ, P. Hadrava – Astronomy in the Czech Republic 3 tion) are located in Garching near Munich, Germany, ESO operates three Telescopes and Instrumentation observational sites in the Chilean Ata- T. Szeifert et al. – FORS1 is getting Blue: New Blue Optimised Detectors cama desert. The Very Large Telescope and High Throughput Filters 9 (VLT), is located on Paranal, a 2 600 m W. Freudling et al. – Towards Precision Photometry with FORS: high mountain south of Antofagasta. At A Status Report 13 La Silla, 600 km north of Santiago de R. Siebenmorgen et al. – Exploring the Near-Infrared at High Spatial Chile at 2 400 m altitude, ESO operates and Spectral Resolution: First Results from CRIRES Science Verification 17 several medium-sized optical tele F. Gonté et al. – The First Active Segmented Mirror at ESO 23 scopes. The third site is the 5 000 m C. Haupt, H. Rykaczewski – Progress of the ALMA Project 25 high Llano de Chajnantor, near San T. Wilson – ALMA European Project Scientist Appointed 31 Pedro de Atacama. Here a new submillimetre telescope (APEX) is in opera- Astronomical Science tion, and a giant array of 12-m submil- J.-P. Beaulieu et al. – Hunting for Frozen Super-Earths via Microlensing 33 limetre antennas (ALMA) is under P. E. Nissen et al. – Sulphur Abundances in Metal-Poor Stars – development. Over 1600 proposals are First Result from CRIRES Science Verification 38 made each year for the use of the ESO R. Scarpa et al. – Using Globular Clusters to Test Gravity telescopes. in the Weak Acceleration Regime 41 J. Zuther et al. – Dissecting the Nuclear Environment of Mrk 609 The ESO Messenger is published four with SINFONI – the Starburst-AGN Connection 44 times a year: normally in March, June, S. Savaglio et al. – GHostS – Gamma-Ray Burst Host Studies 47 September and December. ESO also C. Tapken et al. – The Puzzle of the Lya Galaxies: New Results from the VLT 51 publishes Conference Proceedings and other material connected to its activi- Astronomical News ties. Press Releases inform the media M. Grenon – Nature Around the ALMA Site – Part 2 57 about particular events. For further U. Grothkopf et al. – Using the h-index to Explore the Scientific Impact information, contact the ESO Public of the VLT 62 Affairs Department at the following ad- F. Primas – Status of Women at ESO: a Pilot Study dress: on ESO Staff Gender Distribution 67 M. Sterzik, C. Dumas – Report on the International Workshop on ESO Headquarters Observing Planetary Systems 72 Karl-Schwarzschild-Straße 2 R. Warmels, G. Zech – The Re-launch of the ESO Web 73 85748 Garching bei München Fellows at ESO – M. Messineo, L. Parker 75 Germany Personnel Movements 76 Phone +498932006-0 ESO Fellowship Programme 2007/2008 77 Fax +49893202362 Announcement of ALMA Community Meeting [email protected] and Surveys for ALMA Workshop 78 www.eso.org Announcement of the MPA/ESO/MPE/USM 2007 Joint Astronomy Conference on Gas Accretion and Star Formation in Galaxies 78 The ESO Messenger: Editor: Jeremy R. Walsh Technical editor: Jutta Boxheimer Technical assistant: Mafalda Martins www.eso.org/messenger/

Printed by Peschke Druck Schatzbogen 35 81805 München Front Cover Picture: The three types of ALMA antenna at the ALMA Test Facility at Germany Socorro, New Mexico are shown, from left to right: US (Vertex RSI); European (AEC Consortium); Japanese (Mitsubishi). Since this photograph, the Japanese antenna © ESO 2007 has been removed and the US and European antennas have been linked interfero- ISSN 0722-6691 metrically (see ESO PR 10/07). Photograph by Hans Hermann Heyer (ESO).