The Messenger

No. 151 – March 2013 Progress on the VLT deformable secondary deformable mirror VLT the on Progress KMOS Commissioning of dwarf galaxies Ultra-faint redshift survey The VIPERS Telescopes and Instrumentation

Upgrading VIMOS — Part II

Peter Hammersley1 Figure 1. VIMOS on the Nasmyth Ronald Brast1 platform of VLT UT3. Paul Bristow1 Pierre Bourget1 Roberto Castillo1 Hans Dekker1 Michael Hilker1 Jean-Louis Lizon1 Christian Lucuix1 Vincenzo Mainieri1 Steffen Mieske1 Dan Popovic1 Claudio Reinero1 Marina Rejkuba1 Chester Rojas1 Ruben Sanchez-Jannsen1 Fernando Selman1 Alain Smette1 Josefina Urrutia Del Rio1 Javier Valenzuela1 Burkhard Wolff1

1 ESO

VIMOS is the powerful visible (360– – integral field unit (IFU) spectroscopy and operational procedures; and opera- 1000 nm) imager and multi-object/inte- with three fields of view: 13 by 13, tional efficiency. gral field spectrometer mounted on 27 by 27, and 54 by 54 arcseconds the VLT Unit Telescope 3, Melipal. Its depending on the specific mode This article discusses the results of this high multiplex advantage makes it ideal requested. second phase. More technical details for undertaking large-scale spectro- on the overall upgrade programme can scopic surveys of faint sources. In order VIMOS and its commissioning on the VLT be found in Hammersley et al. (2012). to extend the life of the instrument, im in 2002 were described in Le Fevre et al. prove its performance and prepare for (2002) and in operation by D’Odorico et possible large-scale surveys, in 2009 it al. (2003). After eight years of operation it Improving image quality was decided to upgrade VIMOS. The became necessary to upgrade the instru- first phase of the upgrade, which in ment in order to address various issues Following the change of the detector, it cluded replacing the detectors and the and to extend its useful life. The first became apparent that the optimum focus fitting of an active flexure compensation phase of the upgrade was implemented was changing across the detector due system, has been previously reported; in 2010, (Hammersley et al., 2010) and to a tilt between the detector and the re- this article describes the second stage included: imaged focal plane. This meant that if the of the upgrade, which has improved – Replacement of the shutters, which detector was well focused at its c entre, the delivered image quality and stability. were worn out. then the edges would not be as well – Replacement of the CCD detectors, focused. Due to the optical configuration which has improved the sensitivity of VIMOS this could lead to the images The instrument and upgrades in the red and reduced the fringing. at the corners of each detector becoming – Reduction of the instrument flexure. significantly elongated. VIMOS has four identical arms, each – Provision of new mask cabinets that with a 7 by 8 arcminute field of view on keep masks in position more reliably. In May 2011 an intervention was made the sky with a gap between the fields – Improvement of the data reduction to correct this effect by moving one of 2 arcminutes. The instrument offers pipeline. of the lenses and the detector laterally three main modes: with respect to the rest of the optics. – UVBRIz-band imaging covering four The second upgrade phase took place in This reduced the tilt between the tele- fields each 7 × 8 arc-minutes; 2011–12 and addressed a number of scope focal plane and detector by typi- – slitlet-based multi-object spectroscopy issues which became apparent following cally a factor five. At the correct focus with spectral resolutions from a few the first phase: image quality; the focus only the extreme corners of the array hundred to 2500 in each of the four mechanisms and their control; the effi- showed a small amount of astigmatism. imaging fields; ciency of the HR-blue grism; calibration Figure 2 shows the evolution of average

2 The Messenger 151 – March 2013 Figure 3. Variation of the FWHM in pixels with rotator angle for VIMOS channel 3. The dashed lines show the case with no focus compensation and the solid lines with compensation.

"G@MFDC OHW

CDSDBSNQ ',

%6 "NQQDBSDC 6',

SHKS %

l l 8D@Q 1NS@SNQ@MFKDCDFQDDR

Figure 2. Evolution of the image FWHM in pixels very complicated and it was very easy to so a further intervention in October 2012 since 1 January 2009 for VIMOS channel 4. The red inadvertently make mistakes which were was required to correct this. points correspond to the average FWHM of the pin- holes within 800 pixels of the centre; blue between not immediately obvious. 800 and 1200 pixels and green to those beyond Figure 3 shows the variation in FWHM 1200 pixels (see the schematic of the regions used In March 2012 the original focus stepper with rotator angle when observing the on the detector to the upper left ). Arrows mark when motors were replaced with DC motors, pinhole mask for the three colour-coded the detector was changed and the tilt corrected. each with an encoder. The software was regions designated in Figure 2. The updated to allow the focus offset to now dashed lines show the FWHM with no image quality in three regions of detector take into account rotator angle and compensation with rotator angle and 4 since 1 January 2009. The data were grism as well as temperature and filter for the solid lines indicate the cases with obtained using daytime calibration images each channel. After implementing the compensation. This plot demonstrates of a pinhole mask placed in the focal new motors and encoders, it was found that the instrument is now far closer plane. The dates when the detector was that the mechanism did not have suffi- to the optimum focus in normal operation changed and the tilt corrected are marked cient range to focus all of the modes cor- where the rotator angle is constantly with arrows on Figure 2. The degradation rectly, affecting in particular the IFU, and changing. of image quality following the detector ex change is clear, but following the correction of the tilt, the image quality towards Figure 4. R-band image of the globu- the edge of the detector has significantly lar cluster M55 taken in October 2012, after the focus upgrade. This shows improved. Currently, approximately 90% the whole field of view in channel 3 of the imaging area has an image full (7 by 8 arcminutes). The dark area to width at half maximum (FWHM) < 2.4 pix- the top right is caused by the guide els and an ellipticity below 0.1, whereas probe vignetting the image. prior to the upgrade it was closer to 70%.

Focus control

The original focus mechanism and control software also limited the performance of the instrument. Among the problems were: the stepper motor could lose steps and so lead to a drift in the focus position of the camera; the camera focus changed significantly with the rotator angle and this could not be corrected; it was not possible to control the focus for each grism; updating the focus parameters in the control software was

The Messenger 151 – March 2013 3 Telescopes and Instrumentation Hammersley P. et al., Upgrading VIMOS — Part II

-DVENBTR Figure 6. The spectral ,DBG@MHRL resolution in the red, blue and central regions "NQQDBSDC of lamp spectra, colour- 3HKS coded red, blue and green, taken with the "G@MFDC HR-orange grism in IFU #DSDBSNQ mode for channel 1 is shown. The dates when the detector was BNMCR changed, the tilt cor- B RQ rected and the new @Q focus mechanism were implemented are all 6',

% marked. It should be noted that this is one of the more extreme examples.

7OHWDK 8D@Q

Figure 5. The variation of the stellar FWHM, in arc- tre of the globular cluster (top right). focus was not optimum then the resolu- seconds, as a function of the X position on the There is some elongation in the bottom tion was degraded, particularly at each image shown in Figure 4. corners of the image and the FWHM end of the spectral range. The new focus in those regions increases from about control allows the focus to be set for each Figure 4 shows a VIMOS R-band image 0.55 to 0.60 arcseconds. grism and this has led to the resolution of the globular cluster M55, taken with being more uniform between the four 0.5-arcsecond seeing during the last quadrants and over time. The red end of intervention. This uses the full imaging Spectral resolution the spectrum now always has a higher field of view on channel 3. Figure 5 shows resolution than the blue (as it should be), how the image quality varies with posi- The grisms used by VIMOS are placed which was not always the case before- tion on the horizontal axis (X direction). in the pupil and it was originally assumed hand. The sources with FWHM ~ 0.55 arcsec- that these would not significantly affect onds are stars, while extended back- the focus. Tests in May 2011, however, As an illustration of the implication of ground objects and blended stars have showed that this was not the case, and this change for observations, we estimate larger FWHM, in particular near the cen- the high-resolution grisms in particular re that programmes to detect Lyman-α quired a significant focus offset if the emitters at high redshift would have up Figure 7. The total VIMOS efficiency when using the spectral resolution was to be maintained to a 40% gain in sensitivity just because old (purple) and new (green) HR-blue grisms is shown. across the whole detector. When the the red end of the HR-red spectrum

Figure 8. The evolution of the average technical down time of VIMOS from 2008 to 2011 showing the improvement resulting from the upgrade activities.

VIMOS downtime 12.0% 10.0% X

8.0% jBHDMB $E

6.0% 4.0%

2.0%

0.0% 2008 2009 2010 2011 6@UDKDMFSGML

4 The Messenger 151 – March 2013 is now in focus. Figure 6 shows the evo- of the maintenance procedures have 3) Opto-mechanically, VIMOS is more lution of the resolution of the HR-orange been modified and strengthened, such stable, which makes the instrument grism for channel 1 since 2009. The as making a test insertion every time simpler to calibrate. dates when the detector was changed, a new mask is loaded into the instrument. 4) There is a higher and more stable the tilt corrected and the new focus As Figure 8 demonstrates, these proce- image quality across the whole mechanism installed are marked. As is dures have noticeably reduced the tech- d e t e c t o r . apparent, since March 2012 the red spec- nical down time. 5) The observing efficiency has improved. tral region, in particular, has improved, 6) The technical down time has although some fine tuning is still required. Additional steps have also been taken decreased. to make the science operations more efficient. One example is the elimination As a result, VIMOS is now a significantly HR-blue grism of the mandatory need for pre-imaging more powerful instrument that when it using the PILMOS mode to prepare the was originally mounted on the telescope The original HR-blue grism had a relatively masks, which can now be cut directly, and it is ready for many more years of low transmission and so early on when based on user catalogues (see Bristow et ground-breaking science. the upgrade was planned it was decided al., 2012). to replace it with a Volume Phase Holo- graphic (VPH) grism. The transmission of References the new grism is up to about 50% higher An upgraded VIMOS Bristow, P. et al. 2012, The Messenger, 148, 13 and there is useful transmission below D’Odorico, S. et al. 2003, The Messenger, 113, 26 360 nm (Figure 7). The spectral resolution The VIMOS upgrade programme, which Hammersley, P. et al. 2010, The Messenger, 142, 13 has, however, been reduced by about is now nearing its conclusion, has Hammersley, P. et al. 2012, SPIE, 486, 5MH 30% and the new dispersion is 0.71 Å per been made possible by a significant and Le Fevre, O. et al. 2002, The Messenger, 109, 21 pixel. successful collaboration between the ESO staff at Garching and Paranal. The most important improvements are: Operations 1) The instrument has a better sensitivity in the red. A significant effort has been made to 2) There is far lower detector fringing, al improve the reliability of VIMOS. Some lowing better sky subtraction in the red. ESO/R. Gendler ESO/R.

VIMOS colour image of the barred spiral galaxy NGC 1097, with additional colour information from an image taken by amateur astronomer Robert Gendler superimposed. VIMOS images in B-, V- and R-bands were combined and highlight the star formation regions in the spiral arms, the dust lanes in the bar and the starburst ring around the active galactic nucleus. The companion elliptical galaxy is NGC 1097A at a similar distance of 20 Mpc. See Picture of the Week 11 July 2011 (potw1128a) for more details.

The Messenger 151 – March 2013 5 Telescopes and Instrumentation

Six Years of Science with the TAROT Telescope at La Silla

Alain Klotz1 Michel Boer2 Jean-Luc Atteia1 Bruce Gendre1 Jean-François Le Borgne1 Eric Frappa3 Frederic Vachier4 Jerome Berthier4

1 IRAP-Observatoire Midi Pyrénées, Toulouse, France 2 ARTEMIS-CNRS/OCA/UNS, Nice, France 3 Planetarium de Saint-Etienne, France 4 IMCCE-Observatoire de Paris, France

The TAROT telescopes are a pair of robotic autonomous observatories with identical suites of instrumentation, with one located in each hemisphere. The southern TAROT telescope, which was installed in 2006 at the La Silla Observatory, uses more than 90% of the clear night-time, and has become a very reliable and productive instrument. The primary objective of TAROT is the detection and study of the optical counter-parts of cosmic gamma-ray bursts, and many results have been obtained in this area. But several other topics, ranging from stellar physics to supernovae, have also been addressed successfully thanks to the telescope’s Figure 1. A wide-field image of the nearby early-type (more than 5 by 5 degrees) provided by flexibility. We present the main scientific galaxy NGC 5128, which hosts the radio source the BATSE instrument aboard the Comp- Centaurus A, demonstrating the TAROT field of view results obtained by the TAROT robotic of 2 by 2 degrees. ton Gamma Ray Observatory (CGRO) observatory at La Silla. satellite. In 1997 the BeppoSAX satellite of TAROT at La Silla have been pre- observed the first X-ray afterglow (Costa sented by Boër et al. (2003). At present, et al., 1997) and could provide a pre- TAROT (Télescope à Action Rapide pour the reliability of TAROT is such that more cise position to the Nordic Optical Tele- les Objets Transitoires — Rapid Action than 90% of the available time (i.e., scope (NOT) telescope which, in turn, Telescope for Transient Objects) consists cloudless night-time) is used for scientific recorded the first optical afterglow (van of two robotic autonomous observato- observations. Paradijs et al., 1997). ries located at the ESO La Silla Observa- tory and at the Observatoire de la Côte Optical detection enables the GRB red- d’Azur, Calern Observatory in France. Observation of gamma-ray bursts shift to be measured. This was the They are 25-centimetre aperture tele- ultimate proof that these objects originate scopes with a field of view of 2 by 2 de The TAROT telescopes were designed from distant, cosmological sources. grees (see Figure 1) and a pixel scale in 1995 in order to catch the optical coun- Current models of gamma-ray bursts of 3.3 arcseconds. Images are recorded terparts of gamma-ray bursts (GRBs). involve either the disruption of a massive by an Andor 2k by 2k thinned CCD cam- At that time, GRBs were known as short star with the fall-off of a transient accre- era. With a six-position filter wheel, the events (typically a few seconds) observed tion disc onto a newly born black hole user can choose between one of the only by high-energy instruments on satel- and the emission of a powerful, highly BVRI filters, a special graded neutral den- lites. There were however theoretical relativistic collimated jet, or the coales- sity V filter and an open (clear) position. predictions that GRBs should be also cence of a binary system of compact The equatorial mount can slew to any detectable at optical wavelengths (Rees objects (neutron star — neutron star or part of the sky in less than ten seconds & Meszaros, 1992). The design of TAROT black hole — neutron star); see Gehrels & (Klotz et al., 2008). The technical details was constrained by the large error boxes Mésáros (2012).

6 The Messenger 151 – March 2013 Figure 2. The TAROT La Silla telescope is located at observations before the end of the high Figure 3. The full Moon illuminates the TAROT the foot of the hill below the ESO 3.6-metre tele- energy prompt emission. Since 2001, observatory during a night in January 2007 when scope in the former GMS building. Computers and the great comet C/2006 P1 McNaught was visible electrical devices are stored in the adjacent shelter. 120 GRB triggers have been observed by with the naked eye. The telescope does not require any human presence both TAROT instruments. Ten of them and observes every (clear) night. were optically detected by TAROT during the prompt high energy emission, giving ure 4). The comparison of the brightness very important science data. Another variation in the optical with the flux vari TAROT Calern saw its first light in 1998. advantage of TAROT early observations ation in gamma-ray energy gives precious At about the same time, a rapid notifi of GRBs is the rapid determination of an information about the emission processes cation service profiting from all the inter- accurate position of the optical counter- (Gendre et al., 2012). To our knowledge net capabilities, such as “sockets”, was part. This position can then be sent TAROT is the only instrument able to pro- created. The Gamma-ray Coordinates to large facilities such as the VLT, allow- vide continuous light curves of the GRB Network1 (GCN) promptly distributes the ing for spectroscopy while the source events, i.e. without any dead-time for the coordinates of GRBs detected by satel- is still bright enough, with 97% of the lites to ground facilities within a second GRB redshifts determined less than one or less. From 1998 to 2001, 21 CGRO– day after the trigger. BATSE GRBs were monitored by TAROT Calern. The High Energy Transient During the first few minutes after the GRB Explorer II (HETE II) and the International trigger, the optical emission can display Gamma-Ray Astrophysics Laboratory large variations on a timescale of a sec- (INTEGRAL) satellites sent the triggers ond (or even less). Classical experiments for the period 2001–2004. Swift2 was record a set of images, typically of 5 to launched in 2004 and sends about 10 seconds duration, during the first few 100 GRB alerts per year within an error minutes. However, with a readout time box of 6 by 6 arcminutes. The X-ray of not less than 5 seconds, that means a telescope and the Ultra-violet/Optical Tele dead time of 50%! It is then impossible Figure 4. Trailed image of GRB 121024A. To obtain scope (UVOT) visible camera onboard to obtain a continuous light curve, and a time-resolved optical light curve during the first Swift can reduce this uncertainty to a few hence to draw meaningful conclusions minute of the observation of a GRB, we trail the arcseconds. about the prompt emission part of the image such that each star occupies a small 10-pixel light curve, or even for flares during the track on the frame. In this case TAROT observations started 45 seconds after Swift detected the event. The second TAROT instrument was afterglow of the GRB. We implemented The stars in the middle and right part of the image installed at ESO La Silla Observatory in as a workaround a specific operating have a constant brightness during the exposure autumn 2006. It is located in the former mode: the first image, which lasts 60 sec- while the GRB optical counterpart is the left trail. At GRB Monitoring System3 (GMS) build- onds, is trailed in such a way that each the start of the trail the brightness was R = 14.5 mag. At the end of the trail the magnitude had increased ing at the foot of the hill that is home to star occupies a small ten-pixel track. If an by 1.5 magnitudes only 60 seconds later! Just after the ESO 3.6-metre telescope (see Fig- object, such as the GRB source, is rap- this image, TAROT quickly provided the accurate ures 2 and 3). Since 2006, the pair of idly variable, this will be reflected in the position of the GRB allowing spectroscopy to be TAROT telescopes has covered the two trail corresponding to its position, allow- obtained with the VLT X-shooter spectrograph less than two hours later (Tanvir et al., GCNC 13890). hemispheres. The rapidly slewing mount ing the derivation of a continuous light The redshift of the source is 2.3, corresponding to makes it possible to start the optical curve with a time bin of 6 seconds (Fig- an event that occurred 10.8 billion years ago.

The Messenger 151 – March 2013 7 Telescopes and Instrumentation Klotz A. et al., Six Years of Science with the TAROT Telescope at La Silla

first minute. Because of the very rapid intrinsic variability of GRBs, this feature is 0.06 very important and allows us to draw sig- 0.04 d) 0.02

nificant conclusions by comparison C( 0.00 between the gamma-ray signal and the 0– optical emission as seen by TAROT. –0.02 –0.04 Figure 6. TAROT La Silla recorded this image Thanks to the presence of other experi- without any diurnal motion and stars appear as 11.60 trails. The trail in the centre of the image is of the ments on the same site, namely GROND star TYC 0611-00505-1 which was occulted by the (Greiner et al., 2007) and REM (Chincarini x. 11.80 asteroid (227) Philosophia for 6.41 seconds on et al., 2008) the ESO La Silla Observatory ma 12.00 6 November 2011. This duration corresponds to an g. asteroid size of 74 kilometres. provides a unique set of instruments that 12.20 Ma work together to observe the optical 12.40 counterparts of GRBs. TAROT and REM Earth. TAROT is among the few tele- are rapid telescopes that can record the –0.3 0.0 0.3 0.6 0.91.2 scopes that can easily monitor a star for first few minutes of the GRB events. After Blazhko phase a possible occultation. In practice we this, the GROND instrument can detect record all the predicted occultations that very faint counterparts. During the last Figure 5. RR Lyrae stars in the Galaxy are observed occur within less than 1000 kilometres nine years (the SWIFT era) major by TAROT in order to understand the origin of the from the telescope. Ninety-second Blazhko effect. Each dot on the plot represents a advances in GRB science have come light curve characteristic of the RR Lyr star XY Eri images are taken with no sidereal motion. from using the data from these instru- over a night (figure from Le Borgne et al., 2012). The The star occulted appears as a trail with ments. Blazhko period is 41.22 days. The upper plot repre- a gap if we have been lucky enough to sents the delay between the times of the maximum catch the occultation (as was the case for of light and the mean value. The bottom plot represents the magnitude at the maximum of light against the image shown in Figure 6). Sixty such 4 Space environment, Solar System and the Blazhko phase. This effect is monitored for occultations have been measured . The stellar astronomy 400 RR Lyrae stars. duration of the gap can be converted to a length and gives constraints on the Although GRBs are the primary objective worse within a short time, as more satel- size of the minor planet. The date of of TAROT, because of the scarcity of lites are launched, and the risk of cata- the occultation also provides its astro- their occurrence (an alert per week on strophic collisions increases exponen- metric position with an error generally average) and short duration, the time tially. Some orbits, like the geostationary less than 100 milliarcseconds. devoted to the observation of GRBs is orbit, have also become very crowded, short compared to the night-time dura- implying that satellites have to be main- tion. This allows ample time to study tained in their orbital slot and their posi- Extragalactic studies other objects which benefit from the high tion has to be known with a very high throughput and flexibility of TAROT. One accuracy. The use of radar has the ad The discovery of supernovae (SNe) on of these programmes addresses the vantage of allowing good precision for the rise is a very important topic, both to measurement of the pulsation periods of ranging, with the disadvantage of being understand the physics of the explosion Galactic RR Lyrae stars. About 400 stars less precise for the angular position; and for their use in the determination of are monitored. The goal is to monitor however radar measurement requires a distances in the Universe. We decided to period variations and study the Blazhko lot of power for these high orbits. Small start a programme aimed at the earliest effect, a modulation of pulsation period telescopes can give very accurate solu- possible detection of nearby SNe. Four and amplitude which is not yet under- tions. We use TAROT to monitor the posi- hundred nearby galaxies are monitored stood (Figure 5). In 2007 we published a tion of several geostationary satellites each night, and the same field is ob study on period variations on a time with a high accuracy, and to survey the served every three days. Two observation baseline exceeding a century (Le Borgne orbital debris. About 20 000 astrometric campaigns were carried out in 2007 and et al. 2007). More recently we published positions of geostationary satellites are in 2012. Eight supernovae were discov- an analysis of the Blazhko effect for a gathered by TAROT each month. The ered. The most interesting one of them large sample of RR Lyr stars (Le Borgne process (observation, image processing was 2012fr, which exploded in the nearby et al., 2012). for satellite extraction and astrometric spiral galaxy NGC 1365 (Figure 7). As reduction) is fully automated without any the galaxy was observed in detail by the With the widespread use of space for human in the loop. Hubble Space Telescope before the many activities (telecommunications, re explosion, it is possible to constrain the mote sensing, meteorology, etc.), the Occultations of stars by minor planets brightness of the progenitor. SN 2012fr issue of orbital debris has become very provide a very accurate method to deter- is a Type i a supernova that was dis sensitive. Several satellites have been mine the dimensions of asteroids. How- covered by TAROT — La Silla less than lost because of a collision with debris, ever, even with a very precise prediction, two days after the explosion ignited, often of centimetre size; and it is ex it is impossible to forecast with enough giving crucial data for models of super pected that the situation will become accuracy the path of the shadow on the novae. The light curve of SN 2012fr

8 The Messenger 151 – March 2013 Figure 7. TAROT image of the barred generation of GW detectors will be ready spiral galaxy NGC 1365 showing the in 2017 and TAROT will get ready to par- supernova 2012fr discovered with TAROT as the blue source just above ticipate in this exciting new adventure. At the nucleus of the galaxy. SN 2012fr the same time TAROT has been the seed was the brightest apparent supernova for an effective automated network of of 2012. heterogeneous telescopes around the world, and we are finding ways to com- plement and enhance the observation of the fast transient sky from the Earth.

Acknowledgements

The TAROT telescopes were built and are maintained thanks to the technical and financial support of Centre National de la Recherche Scientifique, Région Midi- Pyrénées, Institut National des Sciences de l’Univers (CNRS-INSU), of the Centre National d’Etudes Spatiales (CNES), and observed by TAROT shows that the Education and Public Outreach of the Observatoire de Haute-Provence decay in the B-band is very slow com- (CNRS). TAROT acknowledges also the pared to the standard value. Investiga- TAROT is also used by high school teach- support of the Programme National tions are continuing since the supernova ers who conduct science projects with Hautes Energies (PNHE) for collaborative will be observable for the whole of the their students. Examples of such pro- research through the FIGARO grants. year 2013. Everyone can contribute to grammes include the determination of the We thank the technical staff of various this programme and has a chance to age and distance of star clusters using institutes (IRAP, OHP, DT-INSU and discover a supernova using the dedicated TAROT images, the monitoring of the ARTEMIS) for their dedication and exper- tool SN_TAROT5. position of satellites of giant planets to tise in installing and maintaining TAROT, determine their mass, or the observation enabling a very high level of reliability. of supernovae to determine their type Serendipitous science and distance from their light curve. References We have launched a large scientific pro- Abadie, J. et al. 2012, A&A, 539, 124 gramme which consists of extracting the Prospects Boër, M. et al. 2003, The Messenger, 113, 45 magnitudes of all the objects in all the Chincarini, G. et al. 2008, The Messenger, 134, 30 images taken at both telescopes. For that Since 1998, the TAROT network of tele- Costa, E. et al. 1997, Nature, 387, 783 purpose we have constructed an archive scopes has contributed actively to Damerdji, Y. et al. 2007, AJ, 133, 1470 Gehrels, N. & Mészáros, P. 2012, Science, 337, 932 of the images which resides on the GRB science. Its major contribution has Gendre, B. et al. 2012, ApJ, 748, 59 CADOR computer at the Observatoire de been its unique capability to monitor Greiner, J. et al. 2007, The Messenger, 130, 12 Haute-Provence, France. A first extrac- the first few minutes of the optical emis- Klotz, A. et al. 2008, PASP, 120, 98 tion was done in the period 2005–2007 sion. Its initial goals have been reached Le Borgne, J. F. et al. 2007, A&A, 476, 307 Le Borgne, J. F. et al. 2012, AJ, 144, 39 using images of TAROT Calern only and a and even surpassed and 30 refereed Rees, M. & Mészáros, P. 1992, MNRAS, 258, 41 catalogue of 1175 new periodic variable papers have been published using TAROT van Paradijs, J. et al. 1997, Nature, 386, 686 stars was published (Damerdji et al., data. Although TAROT will continue to 2007). Now more than one million TAROT work on this topic, we are also preparing Links images are stored in the CADOR data- actively for the new horizons of multi- base. A major effort is underway to make messenger astronomy. 1 Gamma-ray Coordinates Network: a full analysis of the images, and to http://gcn.gsfc.nasa.gov 2 update the catalogue. TAROT is already connected to the Swift: https://heasarc.gsfc.nasa.gov/docs/swift/ swiftsc.html ANTARES experiment, a neutrino tele- 3 GRB Monitoring System (GMS): http://www.eso.org/ The Institut de Mécanique Celeste et de scope consisting of lines of photomultipli- public/teles-instr/lasilla/grb.html Calcul des Ephémerides (IMCCE) makes ers installed in the depths of the Medi 4 Listing of TAROT minor planet occultations: use of these images to extract the astro- terranean Sea. TAROT also participated http://www.euraster.net/tarot/ 5 Supernova hunting with SN_TAROT: metric positions of known asteroids. In in the 2010 campaign to follow up the http://cador.obs-hp.fr/sn_tarot/ turn these positions are used by the triggers provided by the gravitational SkYBOT virtual observatory service and wave (GW) interferometers LIGO and 30 000 asteroid positions were extracted VIRGO, and has successfully passed the in 2012. blind tests (Abadie et al., 2012). The next

The Messenger 151 – March 2013 9 Telescopes and Instrumentation

Accurate Sky Continuum Subtraction with Fibre-fed Spectrographs

Yanbin Yang1 Extremely Large Telescope (E-ELT) is significant cross-talk, while fibre-fed Myriam Rodrigues2 to study faint galaxies in the early Uni- spectrographs can now potentially reach Mathieu Puech1 verse at very high redshifts (e.g., Navarro global throughputs similar to those Hector Flores1 et al., 2010; Cirasuolo et al., 2011). The of classical multi-slit spectrographs (e.g., Frederic Royer1 detection and spectroscopic follow-up of Navarro et al., 2010). Karen Disseau1 these sources will require an accurate Thiago Gonçalves3 and precise sky subtraction process. For However, issues related to the accuracy François Hammer1 instance, in its deepest observations, of sky subtraction remain, and this turns Michele Cirasuolo4 VLT/MOONS (Cirasuolo et al., 2011) will out to be particularly problematic when 5 Chris Evans study sources as faint as HAB = 25 mag in dealing with faint sources. Perhaps the Gianluca Li Causi6 their continuum and emission lines in two most important effects often associ- Roberto Maiolino7 ~ 16 hours of integration, while E-ELT/ ated with fibres, which further limit the Claudio Melo2 MOSAIC (which is a concept design for a accuracy of the sky subtraction com- multi-object spectrograph [MOS] on pared to slits, are: (1) sky continuum vari- the E-ELT; Evans et al., in prep.) will push ations between the position of the ob- 1 GEPI, Observatoire de Paris, CNRS, Uni- this limit up to J/HAB ~ 30 mag in emis- ject and the position at which the sky is versité Paris Diderot, Meudon, France sion, and up to J/HAB ~ 27 mag for con- measured (due to the finite coverage 2 ESO tinuum and absorption line features. of the fibres in the focal plane and the 3 Observatorio do Valongo, Brazil These spectral features will be typically minimum practical distance of closest 4 SUPA, Institute for Astronomy, Univer- observed between bright OH sky lines. approach); and (2) variations in the fibre- sity of Edinburgh, Royal Observatory of However, the near-infrared (NIR) sky con- to-fibre response (due, e.g., to point

Edinburgh, United Kingdom tinuum background is found to be J/HAB spread function [PSF] variations, fringing 5 UK Astronomy Technology Centre, ~ 19–19.5 mag in dark sky conditions or FRD). We refer to, e.g., Sharp & Royal Observatory of Edinburgh, United (Sullivan & Simcoe, 2012), i.e., hundreds Parkinson (2010) for a detailed descrip- Kingdom to a thousand times brighter than the tion of the factors limiting the sky subtrac- 6 INAF–Osservatorio Astronomico di sources to be detected in the continuum. tion accuracy with fibres. After the E-ELT Roma, Italy While the expected relatively bright emis- phase A instrumentation studies fin- 7 Cavendish Laboratory, University of sion lines with restframe equivalent ished, we undertook to better character- Cambridge, United Kingdom widths larger than ~ 15 nm (e.g., Navarro ise these two important potential caveats. et al., 2010) should easily emerge above We now report on some of the results this background, continuum and ab obtained during the past two years. Fibre-fed spectrographs now have sorption line detections will clearly be throughputs equivalent to slit spectro- hampered by possible systematic resid- graphs. However, the sky subtraction ual signal left by the sky subtraction Characterising the sky continuum spatial accuracy that can be reached has often process. For the future detection of such variations been pinpointed as one of the major faint sources, it is therefore critical to issues associated with the use of fibres. check that sky subtraction techniques are The signal from the sky is difficult to pre- Using technical time observations accurate enough, i.e., that one can dict and subtract in the NIR, mainly with FLAMES–GIRAFFE, two observing actually reach accuracies at a level of a because of its strong variability in space techniques, namely dual staring and few tenths of a percent at least. and time. Variations of about 15% in cross beam-switching, were tested and amplitude are typical over spatial scales the resulting sky subtraction accu- In this respect, slit spectrographs have of a few degrees (e.g., Moreels et al., racy reached in both cases was quanti- long been considered as much more 2008). These variations are clearly domi- fied. Results indicate that an accuracy accurate than fibre-fed spectrographs. nated by the flux fluctuations of the bright of 0.6% on sky subtraction can be This is mainly due to two different issues: and numerous OH emission lines, and, reached, provided that the cross beam- (i) fibre-fed spectrographs, if not care- in the second order, by the intensity vari- switching mode is used. This is very fully designed, can suffer significant loss ations of absorption bands produced encouraging with regard to the detec- of light compared to slit spectrographs by molecules of water and other compo- tion of very faint sources with future (resulting from, e.g., fibre cross-talk on nents of the Earth’s atmosphere. Between fibre-fed spectrographs, such as VLT/ the detector or focal ratio degradation these telluric emission and absorption MOONS or E-ELT/MOSAIC. [FRD] which results in a change of aper- lines, the sky signal has a continuum level

ture at the output of the fibres); (ii) it is about ~ 19–19.5 magAB in the J/H bands, more difficult to achieve an accurate sky the origin of which is still poorly under- Why fibres could be an issue when subtraction process with fibres than stood. It could be due to a pseudo- observing faint targets with slits. Recent developments in fibre continuum associated with instrumental technology and careful designs of fibre- residuals, e.g., diffuse scattered light One of the key science drivers for the fed spectrographs can control the issues from the wings of bright emission lines future instrumentation of the Very of the first kind. For instance, good spac- within the spectrograph (Trinh et al., Large Telescope (VLT) and the European ing of fibres on the detector can avoid 2013), or to continuum radiation from

10 The Messenger 151 – March 2013 constituents of the atmosphere. To our beam-switching observations, so the knowledge, the spatial and temporal vari- - tele scope guiding had to be switched off ability of this sky continuum as a function during all the dithered B exposures. In of both space and time has never been principle, the pointing error during offsets $ characterised. is better than 0.2 arcseconds, which is much smaller than the diameter of the We first investigated these issues using ! fibres (1.2 arcseconds). However, in order archival VLT/FORS2 narrowband imag- to prevent any risk of significant misalign- ing and spectroscopy data. Over time- ments between the objects and the fibres scales of a few tens of minutes, Puech et during the dithered B exposures, an al. (2012) and Yang et al. (2012) found NEERDSŭ A–B–A–B-like sequence was preferred that the sky continuum background ex instead of the usual A–B–B–A-like hibits spatial variations over scales from se quence. This preserved the signal-to- ~ 10 to ~ 150 arcseconds, with total noise ratio and only resulted in larger amplitudes below 0.5% of the mean sky overheads. Each individual (A or B) expo- background. At scales of ~ 10 arcsec- sure was ten minutes. The three con onds or below (on which the sky is likely Figure 1. Illustration of cross beam-switching obser- secutive A–B sequences obtained repre- to be measured with future fibre-fed vations. The astrophysical object of interest is represent a total effective exposure time of one sented as a star. The fibres are positioned in pairs spectrographs), the amplitude of the vari- in the focal plane, with distances of 12 arcseconds hour, immediately after which attached ations is found to be ~ 0.3–0.7%. Note between the two fibres of each pair along the north– flat-field exposures were acquired. that this should still be considered as an south axis. Such a pair is represented by red and upper limit to real sky continuum varia- blue circles. The observing sequence consists of dithering the telescope from position A to position tions, since scattered light and noise vari- B by 12 arcseconds such that the object (and the Data analysis and results ance can be difficult to mitigate in such sky) is always observed within one of the two fibres low signal-to-noise data. Regardless, this of a given pair. Basic reduction steps were performed is a very encouraging result, which sug- using the ESO pipeline (bias correction, gests that sky background subtraction internal calibration lamp flat-fielding, can, in principle, be achieved with an of these pairs were “pure sky”, meaning wavelength calibration and extraction of accuracy of a few tenths of a percent. that no object was observed in any pair 1D spectra). We focused on the sky of fibres. Preliminary results from these continuum background since targets will three pairs were presented in Rodrigues be observed between the sky emission Testing sky subtraction with cross beam et al. (2012). and strong telluric lines (e.g., Vacca et al., switching observations 2003; Davies et al., 2007). Seven spectral The LR8 GIRAFFE setup, which covers regions free of sky emission and absorp- Reaching sub-percent accuracy on sky 820–940 nm with a spectral resolution tion lines were defined (see Figure 2) to subtraction still requires that the varia- of R = 6500, was chosen to obtain spec- test the accuracy of different sky subtrac- tions in fibre-to-fibre response are dealt tra at NIR wavelengths. The target field tion strategies. To increase the statistics, with. For this purpose we requested ESO was observed at low airmass (< 1.2), but limit the impact of the object spec- technical time on FLAMES–GIRAFFE, i.e., when it was relatively close to the trum, we limited the analysis to 15 pairs which is the ESO optical workhorse multi- meridian with an hour angle of less than with object IAB-band magnitudes fainter object fibre-fed instrument at VLT/UT2. ~ 30 minutes. During the observations, than 21. The mean magnitude of these

Such tests reveal that accuracies of few the Moon was located ~ 28 degrees 15 objects is found to be IAB = 21.88 mag, tenths of a percent can indeed be re away from the target field, contributing which corresponds to a continuum flux ached, provided that a cross beam- about 50% to the sky continuum back- that is ~ 7 times fainter than the contribu- switching observing sequence is used ground flux. The total continuum back- tion from the sky continuum. To compare (see Figure 1). In the following, we de ground of the observations reaches the sky continuum subtraction accuracy –2 scribe the observations conducted and mAB ~ 19.7 mag arcsecond , which is reached using cross beam-switching the results obtained. very similar to the J-band sky continuum observations, we also reduced the data brightness in dark conditions (Sullivan in order to mimic a simpler staring mode We undertook technical observation with & Simcoe, 2012) and therefore particu- observing strategy. Both observing and FLAMES–GIRAFFE on 8 March 2012, larly well-suited to our purposes. reduction methods are detailed below. using the Medusa mode with clear conditions and a seeing of ~ 0.9 arcseconds. The observations were carried out using In staring mode observations, an object The fibres were distributed over a 20 by a cross beam-switching configuration in and the nearby sky (12 arcseconds 20 arcminute region in the zCOSMOS which the telescope was offset by 12 arc- away in the present case) are observed field (Lilly et al., 2007). Seventy fibres were seconds along the north–south axis three with a pair of fibres simultaneously. For distributed in pairs separated by 12 arc- times in a row (see Figure 1), resulting each object in the sample, we derived seconds and oriented along the north– in an A–B–A–B–A–B sequence. FLAMES two spectra by combining the three A south axis, as illustrated in Figure 1. Three does not have a template for cross exposures and the three B exposures,

The Messenger 151 – March 2013 11 Telescopes and Instrumentation Yang Y. et al., Accurate Sky Continuum Subtraction with Fibre-fed Spectrographs

W %KT B B B B B 6@UDKDMFSGML

W %KT B B 6@UDKDMFSGML

Figure 2. Sky spectrum from 820 to 920 nm ob tained after combining 72 sky fibres. OH emission lines and atmospheric absorptions, i.e., telluric lines, can be seen almost everywhere. Only a few relatively clean continuum regimes are left, such as the red regions marked as c1 to c7, which are selected for further analysis. respectively. The resulting exposure time combine all six exposures to produce a traction) as the relative mean between of each spectrum is 30 minutes. Here, spectrum with a one-hour integration. the object and sky spectra (divided by the there is no point in combining all A and B In cross beam-switching mode, object mean sky). As we argued, considering exposures together since, by definition, in and sky are indeed observed by the all such measurements for all exposures staring mode the sky is sampled on only same fibre but at different times, and the of all objects in the sample simulates a one side of the object, and the object sky is sampled at both sides around the 105-hour integration, providing us with and sky are observed with different fibres objects. Finally, if one combines all the well-defined statistics for measuring the which would lead to large residuals. Thus, exposures of all the objects together, one mean expected accuracy as well as its we simply subtracted the integrated B can actually simulate the result of a associated uncertainty, as shown in Fig- spectrum from the integrated A spec- 15-hour on-sky spectrum. Combining all ure 3. We found in this case a mean trum. Since the objects have fluxes that the measurements in the seven distinct ac curacy of 0.6 ± 0.2%. In comparison, are significantly fainter than that of the spectral windows can mimic a simulated the accuracy is degraded by a factor sky continuum (see above), the resulting integration time of up to 105 hours. This of ~ 10 when using the simple staring- difference can be considered as a first- is sufficiently long so as to sample deep mode observations. This confirms order estimate of the residuals from the integration times for future VLT or E-ELT the preliminary analysis conducted by sky subtraction process. observations (i.e., of a few tens of hours). Rodrigues et al. (2012), i.e., that cross In the absence of any residual systematic beam-switching observations allow us to In cross beam-switching mode, the tele- effect, one would expect that the re reach sky subtraction accuracies of a scope is dithered by 12 arcseconds sulting signal-to-noise ratio of the com- few tenths of a percent. along the north–south axis between the bined spectrum is reduced by a factor A and B positions. During the three con- 3.8 (combining the 15 exposures secutive A–B sequences, a given object together) and 10 (combining all the expo- Reaching the noise floor is always observed by one of the fibres sures of all objects together), respectively. of the pairs alternately. Within a single We also investigated the exposure time A–B sequence, the object spectrum can For each exposure of all objects, we esti- needed to reach the noise floor at which be extracted twice (once in A and once mated in each spectral window the re the signal-to-noise ratio of the observa- in B) and subtracted one from another. In sidual local error after sky continuum tions becomes limited by systematic contrast to the staring mode, one can subtraction (i.e., the accuracy of sky sub- effects associated to sky continuum

12 The Messenger 151 – March 2013 10 Figure 4. Local residual error as a 0.6 ± 0.2% function of integration time. The black 50 points, with error bars, illustrate a decrease with the square root of integration time. The two horizontal red ) lines represent the range of variations

40 r (% found at ~ 10 arcsecond scales in

ro the sky continuum background from er

l Puech et al. (2012) and Yang et al. (2012). 30 sidua re N

l 1 ca Lo 20

110 100 Integration time (hr) 0 –0.150–0.100–0.050–0.00 .05 .10 .15 Mean residual signal

Figure 3. Histogram of the mean residual signal 70–100 hours of integration. Besides, it is lengths, where the impact of scattered measured in each spectral window of all exposures interesting to note that the 0.6% floor in light keeps increasing. of all objects observed with FLAMES–GIRAFFE. The mean value estimates the mean residual error residual local error is very close to the signal, i.e., the accuracy of the sky continuum sub- measured variations of the sky continuum The results reported here strongly sug- traction, obtained with simulated 105-hour long background obtained by Puech et al. gest that the issue of the sky continuum exposures. The red region represents the uncer- (2012) and Yang et al. (2012), which range subtraction is not a show-stopper for tainty associated with this value, which was derived using the standard error of the mean, i.e., as the between ~ 0.3 and 0.7%. This could indi- the study of very faint sources with fibre- standard deviation of the distribution divided by the cate that long-exposure observations can fed spectrographs. Given the flexibility square root of the sample size. really remove most of the instrumental of these systems, it is likely that they will inaccuracies and reach the physical limit play a very important scientific role in due to sky continuum variations. The the future generation of multi-object in 0.3% floor found by Sharp & Parkinson struments such as MOONS for the VLT subtraction inaccuracies. For this, we (2010) could be due to the smaller varia- (Cirasuolo et al., 2011) or MOSAIC for the repeated the above measurements in tions in the 600 nm sky continuum, com- E-ELT (Evans et al., in prep.). samples of different sizes, which simulate pared to the wavelengths around 900 nm different integration times, as argued that we are probing here. above. Results are shown in Figure 4. At References short integration times, the local residual It is important to recall that the results Cirasuolo, M. et al. 2011, The Messenger, 145, 11 error is dominated by random errors reported here were obtained on 1D Davies, R. I. 2007, MNRAS, 375, 1099 associated with the photon noise. It is ex spectra with non-optimal conditions. It is Lilly, S. et al. 2007, ApJS, 172, 70 pected from simple Poisson statistics likely that using more advanced proce- Moreels, G. et al. 2008, Exp. Astr., 22, 87 that this error decreases as the square dures in the data reduction (see Sharp & Navarro, R. et al. 2010, Proc. SPIE, 7735, 88 Puech, M. et al. 2012, Proc. SPIE, 8446, 7 root of the integration time, until it reaches Parkinson, 2010) and with more control Rodrigues, M. et al. 2012, Proc. SPIE, 8450, 3 a floor (see Sharp & Parkinson, 2010). over the instrument design regarding the Sharp, R. & Parkinson, H. 2010, MNRAS, 408, 2495 Given the limited size of our sample, it is potential sources of inaccuracies detailed Sullivan, P. W. & Simcoe, R. A. 2012, PASP, difficult to measure such a decrease pre- above, one might be able to lower the 124, 1336 Trinh, C. et al. 2013, MNRAS, submitted, cisely, but a gradual decrease followed floor at which signal-to-noise ratio is lim- astro-ph/1301.0326 by a floor can indeed be seen in Figure 4. ited by such systematic effects, and Vacca, W. D. et al. 2003, PASP, 115, 389 This floor is reached after 10–25 hours possibly to shorter integration times. Wyse, R. F. G. & Gilmore, G. 1992, MNRAS, 257, 1 of integration at a value of 0.6%. At such More over, these results support the idea Yang, Y. B. et al. 2012, Proc. SPIE, 8446, 7 large integration times, the local residual that controlling and measuring instru- error starts to be dominated by systematic mental scattered light would remain the effects from the sky continuum subtrac- main obstacle to accurate spectroscopy tion. of faint sources. We argued above that these results should apply up to J-band, The trend shown in Figure 4 is similar but it will be important to confirm these to that found by Sharp & Parkinson (2010) results and characterise the sky con at 600 nm, with a ~ 0.3% floor after tinuum variations at even longer wave-

The Messenger 151 – March 2013 13 Telescopes and Instrumentation

Delivery of the Second Generation VLT Secondary Mirror (M2) Unit to ESO

Robin Arsenault1 accomplished by replacing the conven- ful and Microgate had to resort to another Elise Vernet1 tional secondary (M2) mirror with an supplier for the manufacture of the first Pierre-Yves Madec1 adaptive secondary, implementing the science shell. REOSC was awarded the Jean-Louis Lizon1 Four Laser Guide Star Facility (4LGSF) contract by Microgate in August 2009 Philippe Duhoux1 and installing adaptive optics (AO) mod- and the mirror delivery took place in Jan- Ralf Conzelmann1 ules on the various foci. Until recently, uary 2012. The shell has since been Norbert Hubin1 the AO modules consisted of GRAAL furbished with magnets, coated and inte- Roberto Biasi2 (Ground Layer Adaptive optics Assisted grated into the DSM. Following the de Mario Andrighettoni2 by Lasers; Paufique et al., 2012) for livery of the first shell, ESO placed a con- Gerald Angerer2 HAWK-I and GALACSI (Ground Atmos- tract with REOSC for a second, spare, Dietriech Pescoller2 pheric Layer Adaptive Corrector for thin shell. Chris Mair2 Spectroscopic Imaging; Stroebele et al., Federico Picin2 2012) for the Multi-Unit Spectroscopic The DSM system and its design have Daniele Gallieni3 Explorer (MUSE), but lately the Enhanced been presented in a number of papers: Paolo Lazzarini3 Resolution Imager and Spectrograph on AOF manufacture (Arsenault et al., Enzo Anaclerio3 (ERIS) project has been launched and 2010); integration and electromechanical Marco Mantegazza3 ERIS will be installed on the Cassegrain testing (Biasi et al., 2012); stress polishing Luigi Fumi4 focus of UT4 with an upgraded version of the thin shell (Hugot et al., 2011); and Armando Riccardi4 of the SPIFFI near-infrared imaging spec- in a progress report (Arsenault et al., Runa Briguglio4 trograph. With this last addition, all instru- 2012). We will focus here on the perfor- Florence Poutriquet5 ments on UT4 will thus be optimised for mance of the system. Eric Ruch5 use with the 4LGSF and the deformable André Rinchet5 secondary mirror. Jean-François Carré5 DSM high-level functionality Denis Fappani6 There has been major progress since the last report in The Messenger (Arsenault The DSM is contained in a complete et al., 2010), as most systems have now new M2 unit that will replace the actual 1 ESO been delivered to ESO Garching and inte- Dornier M2 unit of UT4. The hub structure 2 Microgate, Bolzano, Italy grated. implements the same interface as the 3 ADS International, Valmadrera, Italy existing one for the telescope spider and 4 Osservatorio Astrofisico di Arcetri, the current Laser Guide Star Facility Florence, Italy The deformable secondary mirror launch telescope. The latter will be re- 5 REOSC, St-Pierre-du-Perray, France installed on the new M2 unit. 6 SESO, Aix-en-Provence, France The DSM was delivered to Garching on 6 December 2012. This represents a The M2 mirror surface is defined by the major milestone for the AOF. It should be thin-shell mirror, 1120 mm in diameter The deformable secondary mirror recalled that initial efforts towards the and 2 mm thick, and the reference body, (DSM), one of the key systems of the development of the DSM and thin-shell which defines a reference surface for VLT Adaptive Optics Facility (AOF), mirrors were initiated at ESO as early as the back (concave side) of the thin shell has been delivered to ESO. It has been 2004 in the framework of Opticon (Figure 1). Both are made of Zerodur. The fully qualified in standalone mode research and development efforts. This reference body (manufactured by SESO, and has successfully passed the tech- delivery initiates the start of the AOF France) is a thick optical piece, light- nical acceptance Europe. Recently it system tests in Garching which will last weighted, with hole patterns to allow the was installed on ASSIST, the test bench for the next 18 to 24 months. passage of the 1170 voice coil actuators. for the AOF, and will undergo optical These are mounted on the cold plate tests, which will complete its prelimi- Microgate and its partner company ADS and apply forces on 1170 corresponding nary acceptance in Europe. With its were involved early on in the project. A magnets glued on the back face of the 1170 actuators and 1.1-metre thin-shell feasibility study was initiated in 2004 and thin shell. Metallic coatings on the shell mirror, it constitutes the largest adaptive concluded in August 2005. A single back face and the front face of the refer- optics mirror ever produced. The DSM source contract was then granted to ence body act as capacitive sensors constitutes a fine accomplishment by Microgate for preliminary and final design used to measure the gap between both. European industry and is set to become studies, which was concluded in Decem- the “flagship” of the AOF on Paranal. ber 2007. A few months later, the present In non-adaptive optics mode, a constant contract was awarded for the manufac- command is applied to the 1170 actua- ture of the DSM. tors to give to the thin shell the VLT M2 The Adaptive Optics Facility (AOF) is prescription figure. This figure will have intended to transform the Very Large The thin-shell mirror development fol- been calibrated on the ASSIST test Telescope (VLT) Unit Telescope 4 (UT4) lowed a similar time frame. Unfortunately, bench. The command is applied at a into an adaptive telescope. This is Opticon funded efforts were unsuccess- sampling rate of 80 kHz, the internal

14 The Messenger 151 – March 2013 of the mirror in order to correct the atmospheric turbulence. A ± 1 N force can be applied to each actuator, which provides considerable stroke for the low order modes (tip, focus and astigmatism) while much more force is required for the high order modes, which can be very stiff. The shell is operated at a gap of ~ 65 μm; given the constraint that this gap should not be below ~ 30 μm, to ensure proper capacitive readout, this means that some ± 30–40 μm stroke is available for turbulence correction (for reference, a typical piezoelectric stack deformable mirror provides less than 10 μm total stroke). The internal control loop of the DSM operates with a given set of force/gap for each actuator. This set of gaps is updated by the adaptive optics real-time computers of GRAAL and GALACSI, and in the future, ERIS, using the Standard Platform for Adaptive optics Real Time Applications (SPARTA) Figure 1. The deformable secondary mirror in its test architecture. The difference from a piezo- stand. In operation the thin-shell mirror is held by the electric stack mirror, for instance, is that actuators with a gap of 65 μm between the shell back face and the reference body front face. The black the DSM internal control loop manages metallic structure surrounding the mirror is called the the dynamics of the mirror in an optimal “EMC skirt” and shields the system from electro- fashion. At the next iteration the SPARTA magnetic interference. real-time computer can send a new command knowing that the previous one control loop frequency, but kept con- offered: two focal stations — Cassegrain has been executed without time delay, stant. The result for the telescope user is and Nasmyth, focusing and centering creep or hysteresis. an equivalent pseudo-rigid M2 mirror like (i.e., rotation of the mirror around its cen- the current Dornier mirror. tre of curvature). The required motions The SPARTA real-time computers imple- are performed with a hexapod, but this is ment various control schemes depend- The M2 local control unit (LCU) software transparent to the user. The active optics ing on the instrument that is being fed: (and the whole system) have been de of the VLT functions in exactly the same ground layer AO correction (GLAO); laser veloped with the intention of minimising way as with the Dornier M2. tomography AO correction (LTAO), both changes in non-adaptive optics mode, so with laser guide stars; and classical that for users and telescope operators, The full potential of the DSM is unleashed on-axis natural guide star AO correction the mirror is set up like a Dornier M2 unit. in adaptive optics mode: here the 1170 (NGAO). The set of modes to be controlled The same adjustment possibilities are actuators are used to change the shape can also be optimised to zonal control

Figure 2. Finite element modelling of the complete DSM shown on the left. It is used as a baseline to compare with the experimental results. On the right, the hub with dummy weights and external encoders to measure flexure. The hub integration and service stand allows the inclination of the hub to be varied to characterise the flexure at the level of the reference body for different orientations. The results of the flexure campaign confirmed the system rigidity at 150 N/mm.

The Messenger 151 – March 2013 15 Telescopes and Instrumentation Arsenault R. et al., Delivery of the Second Generation VLT Secondary Mirror Unit

,NCDŮl2DSSKHMF LRl.UDQRGNNS Figure 3. Response time performance for tilt (upper) and the natural eigenvector mode 101 (lower). The control parameters have been adjusted so that all modes have similar dynamical properties. The specification was 1.2 milliseconds at 90% of command and less than 10% overshoot; all modes are below 0.7 milliseconds. The stiffer the mode (i.e. mode 101), the higher its resonance frequency; thus the bigger challenge is for the low order modes such as tilt, focus, astigmatism, etc.

ƅL M

RHSHN

/N DSM unit system tests

Testing of the DSM started a while ago at subsystem level. The Integration Pro- gress Review was held in May 2011 and one complete week was spent at ADS l and Microgate to inspect all the hardware produced by this time, before the inte 3HLDLR gration of the whole DSM system. The aim was to ensure that all components ,NCDŮl2DSSKHMF LRl.UDQRGNNS were validated before this final step. Both

contractors developed custom tools and test setups for this phase of the project.

At Microgate, where the electronics and software were developed, the corresponding subsystems were inspected and tested: electronic control boards, L actuators, racks and software. A massive ƅ

M amount of data was acquired, which

RHSHN has been reviewed by ESO, and will be

/N built into the system as internal calibration data used during system operation. Mechanical subsystems were also tested and inspected at the ADS premises. The hexapod motion characteristics were tested: centering, focusing, change of l focal station (Nasmyth to Cassegrain), full range, positioning accuracy and motion 3HLDLR cross-coupling. Particular care was taken to assess the mechanical rigidity of the system (see Figure 2). (individual actuators), stiffness modes optics Shack–Hartmann sensor is blind (natural modes of the DSM) or Karhunen– to the telescope aberrations since it is Loeve, or any set defined by the AO fed after the DSM and thus sees a per- Performance specialist. Furthermore, an online algo- fectly corrected wavefront. In other rithm monitors the interaction matrix dur- words, the telescope internal aberrations The most impressive results of the whole ing the observation in order to identify and misalignments are corrected by the system test campaign are probably the mis-registration between the DSM and DSM. The strategy is thus to offload the critical performance specifications, which the wavefront sensors and to update quasi-static aberration seen on the DSM have all been met. Among these are: the the command matrix to optimise the directly to the M1 mirror actuators. Note residual wavefront error after adaptive correction. that the coma correction that is done optics correction, the response time (see by the centering correction of the M2 unit Figure 3), the chopping stroke and its A subtle consequence of using an adap- is the same, whether in non-adaptive or response time. The main verification of tive secondary is that the active optics adaptive optics mode. the DSM performance is the follow-up of the VLT will be inoperative. The active error test. Numerical phase screens have

16 The Messenger 151 – March 2013 1,2NEQDRHCT@KR@ESDQk@SSDMHMF the M2 nominal prescription figure from l the actual convex shape. The specifi cation to be fulfilled by the optical supplier is then to provide a convex face that requires less than 0.1 N (10% of full range) to bring the shell to the 8 nm rms surface error.

l The first science shell reached the speci- fied quality requirement: the convex

2L shape could be brought to 8 nm rms surface error by correcting ~ 800 modes R 1, and this required ~ 0.1 N force (see Fig- ure 4). If all the 1170 modes are cor-

1DRHCT@K rected, the surface error is reduced fur- l ther, but higher forces are required.

The next challenge was the thinning and accurate surfacing of the back face of the thin shell. In order to ensure good dynamical behaviour (response time, electronic damping and homogeneous and low-noise capacitive sensor readout), l the gap between the reference body ,NCDR and thin shell must be homogeneous. The criteria is thus to thin the shell to a Figure 4. The simulated convex shape of the DSM 3D + IDOINE PIT16 homogeneous thickness. Here there is after correction; showing the surface error residuals Target spec both a constraint from the polishing and (rms) in metres versus the number of modes used to Contactual spec achieve the correction. also from the measurement: the acoustic devices used to measure the thickness, although they possess sufficient accu- been simulated at ESO for a calibrated ual root mean square (rms) wavefront racy, are somewhat sensitive and meas- condition of 1.5 arcseconds at a wave- error. The result of this test gives 131.5 nm urements can easily be degraded by length of 0.5 μm, 20 degrees elevation rms wavefront error while the specifica- conditions (surface cleanliness, sensor/ angle and 1000-mode correction. These tion requests 149 nm rms. The internal surface interface, surface roughness, are quite demanding conditions. From control loop of the DSM (between coils parasitic devices running simultaneously, these phase screens one can easily infer and capacitive sensors) represents a etc.). the shape that must be taken by the DSM huge asset at the time of testing as it to correct the wavefront. A file containing allows the subsystem to be fully qualified Despite these difficulties the first shell the time history for all actuators has been before it is integrated into the AOF with was realised to specification and deliv- provided to Microgate. guide stars, external real-time computer ered to ADS in January 2012. Following and optical Shack–Hartman sensors. this, an aluminium coating was applied The test then proceeds by switching on to the back face, leaving 1170 circular the DSM and fooling it into believing that apertures for the gluing of the m agnets the capacitive sensors measure the dis- Thin-shell mirror (Figure 5). This coating has essentially tances in the time history file. The internal an electrical purpose. After the gluing control loop then corrects these offsets. The convex face of the thin shell is pol- of all the magnets, the optical coating is The system measures the capacitive sen- ished to the nominal M2 optical pres deposited on the convex side. sor signals versus time and makes a few cription and then the optical piece is simple assumptions about time delay. thinned to the 2 mm nominal thickness. The last integration step is to glue the At each calculation cycle, a delta can be The defects in the convex shape can central membrane onto the shell; this is measured between the real mirror posi- be relatively high (several micrometres) if done in the setup with the shell held up tion and the sent perturbation. This con- they represent low order deformations; by the actuators and kept in position stitutes the main part of the error signal. but these can then easily be corrected for several hours while the glue is curing. If the error due to the high order modes by the actuators of the DSM. A computer Note that the membrane allows tip and not corrected by the DSM is added to program has been developed by the tilt and piston motion (along the optical this delta, then the result gives the per- Osservatorio Astrofisico di Arcetri in order axis) of the shell, while restraining motion formance of the system in terms of resid- to assess the forces required to obtain perpendicular to the optical axis.

The Messenger 151 – March 2013 17 Telescopes and Instrumentation Arsenault R. et al., Delivery of the Second Generation VLT Secondary Mirror Unit

Figure 5. Left: The thin shell being dismounted. The magnets glued to the back face are visible. Right: The front face of the reference body. The 1170 recesses for the magnets surrounded by the chemically deposited rings of silver coating (for capacitive sensing) can be clearly seen. The copper parts inside the reference body recesses are the caps on top of the voice coil actuators.

ESO has awarded a contract to REOSC and safest conditions. For instance, a pended from a reverse “U” shape han- for a second science shell that will be multi-purpose container has been devel- dling device allowing the shell to be used as a spare. The latter will be fully oped for the thin shell. Its design is the flipped; and the convex half of the shell characterised before the DSM is shipped result of years of experience with previous can be used as a “coating body”. to Chile for commissioning. deformable thin-shell mirrors and detailed finite element modelling (FEM). The con- A similar philosophy has been applied cept consists of two halves holding the to the DSM system itself. Other tools Handling and maintenance thin shell in a sandwich and the spacers enable various maintenance operations: between these two halves are calibrated a test stand has been provided for the A fear often expressed in dealing with to exert a pre-defined load on the shell. hub alone or with the DSM; another stand such a fragile thin-shell mirror is the has been provided for the DSM assem- danger of hosting it in a VLT system. The The shell transport box (STB; Figure 6, bly alone (Figure 6, right); a stand hosts concern is certainly justified, but the left) fulfils several functions as well as the hexapod when it is removed from the suppliers have taken particular care in transport of the shell: the lower (concave) hub; and dummy weights are provided developing detailed procedures and a set half is used as receptacle for the shell to replace missing components, allowing of handling tools to ensure that any han- removal and installation on the DSM; the continual use of the same tools in a bal- dling will be conducted under the best complete STB with shell can be sus- anced configuration.

Figure 6. Left: the shell transport box, which is the DSM multi-purpose handling and protection equipment, is shown. Right: the DSM test stand allows the DSM, with its electronics, to be fully operational in the laboratory.

18 The Messenger 151 – March 2013 Next phases and key milestones for the Figure 7. The DSM AOF mounted on the ASSIST test bench in the ESO Garching integration Now that the DSM has been success- laboratory at the start of fully delivered, the subsequent sequence the test phase. GRAAL of events is straightforward. The AOF is in the foreground. project has now reached a stage where most of the tasks are now sequential and on the critical path. In January 2013 the DSM was mounted on ASSIST (Stuik et al., 2012). There a team from Arcetri Observatory and ESO will fully charac terise the DSM optically. This phase will last around four months and is still the responsibility of the contractor.

ASSIST, with its 1.7-metre main mirror provides a complete optical setup for the DSM; no simple task for a convex secondary mirror (Figure 7). With the use of a fast interferometer, the DSM will first be characterised optically. For the other tests with GRAAL and GALACSI, the input module of ASSIST simulates a con- stellation of sources, natural and laser guide stars defocused and aberrated by calibrated turbulence. The AO modules can be mounted on ASSIST and an output optical module simulates the optical and mechanical interface of the VLT Nasmyth focus.

During that time GRAAL will complete its standalone tests and validation. Then, mounted on ASSIST with the DSM, the whole assembly will be used to fully qual- ify the adaptive optics loop. The source The initial commissioning activities of the References module of ASSIST with phase screens to AOF are expected to last through 2015. Arsenault, R. et al. 2010, The Messenger, 142, 12 generate calibrated turbulence will feed Arsenault, R. et al. 2010, Proc. SPIE, 7736, 20 the DSM and GRAAL. The GRAAL real- Arsenault, R. et al. 2012, Proc. SPIE, 8447, 0J time computer and wavefront sensor will Acknowledgements Biasi, R. et al. 2012, Proc. SPIE, 8447, 88 create realistic conditions for closed-loop Hugot, E. et al. 2011, A&A, 527, A4 Many thanks are due to numerous people who have Kuntschner, H. et al. 2012, Proc. SPIE, 8448, 07 operation. The natural guide star mode been involved, occasionally, but over a period of Paufique, J. et al. 2012, Proc. SPIE, 8447, 116 on-axis of GRAAL will first be tested. many years, and provided unfailing support to the Stroeble, S. et al. 2012, Proc. SPIE, 8447, 115 project: F. Koch for structure analysis and counsel- Stuik, R. et al. 2012, Proc. SPIE, 8447, 118 These tests will constitute a strong basis ling; M. Cayrel for supporting critical steps of development of the thin shell; S. Stanghellini for his expert to continue with GRAAL GLAO correction advice and enthusiasm during the reviews and latest mode tests and characterisation. Then acceptance procedures; J. Schimpelsberger for his GRAAL will be replaced by GALACSI and diligence with all contract amendments and nego the GLAO correction mode of GALACSI tiations; M. Duchateau and R. Brast for their help with electronics design/acceptance reviews. C. Dupuy tested. The second mode of correction of and S. Tordo have always been active in the back- GALACSI (LTAOs for the MUSE narrow- ground to help with integration and interfaces and field mode) will then follow. Before ship- R. Stuik from the University of Leiden has been lead- ment the DSM will be refurbished with ing the development of ASSIST and helping with the interfacing of the DSM on the test bench. Finally, our the spare thin shell whose delivery is Paranal colleagues P. Sansgasset and G. Hüdepohl, planned for the end of 2013. The second who have been our “base of knowledge” concerning shell in the DSM will then be fully qualified VLT M2 units, are thanked together with J.-F. Pirard and validated on ASSIST. for preparing the arrival of the AOF in Paranal and the DSM in particular.

The Messenger 151 – March 2013 19 Telescopes and Instrumentation

ALMA Completes Its First Science Observing Season

Martin Zwaan1 in December 2011. It is expected that the preparation of Phase 2 material and Paola Andreani1 the final quality-assured Cycle 0 data will hosted users for expert face-to-face Andrew Biggs1 have arrived with the PIs by the end of support during proposal preparation and Maria Diaz Trigo1 February 2013. Many teams that received data reduction. It is also important to Evanthia Hatziminaoglou1 ALMA Cycle 0 data are still in the midst emphasise that nearly all contact scien- Elizabeth Humphreys1 of the analysis and paper writing, but a tists for European Cycle 0 projects are Dirk Petry1 number of papers based on Cycle 0 have located at the ARC nodes. ARC nodes Suzanna Randall1 been published already, in addition to the are therefore very well up to speed on the Thomas Stanke1 many based on Science Verification data. specifics of Cycle 0 projects. Thus far, Felix Stoehr1 The exciting results span the whole PIs and CoIs of 20 Cycle 0 projects have Leonardo Testi2 gamut of astronomical research, ranging visited one of the seven ARC nodes for Eelco van Kampen1 from submillimetre galaxies and gamma- face-to-face data reduction support, with ray bursts to shells around asymptotic the purpose of improving the calibration giant branch stars and brown dwarfs. and imaging of their data beyond what 1 European ALMA Regional Centre, ESO More details of Cycle 0 science results was already provided by the observatory. 2 ESO are presented in the summary of the conference “The First Year of ALMA Science” on p. 50. User experience The Atacama Large Millimeter/submillimeter Array (ALMA) has recently com- In September 2012 the second user pleted its first year of science observing Operations and user support satisfaction survey was conducted and the second year is beginning with among the nearly 4000 registered users increased capabilities. The completion High quality end-to-end user support of ALMA. One of the aims of the survey rates for European-led proposals are has always been one of the main pillars of was to query users about their experi- reported. User support activities in the the ALMA operations model. Even for ence with Cycle 0 scientific operations, European ALMA Regional Centres are Early Science, where it has been empha- data processing and support at the summarised, together with the results sised that the execution of observing ARCs and ARC nodes. The user profile of a survey of users. programmes would be done on a best- is dominated by radio and millimetre/ effort basis, ALMA has attempted to pro- submillimetre astronomers using ground- vide optimal user support throughout based facilities. However, up to 40% Wednesday, 2 January 2013, marked the the lifetime of the projects. Contact sci- of the users are experts in wavelengths completion of data-taking for Cycle 0, entists appointed to all Cycle 0 projects longer than the submillimetre, in space- ALMA’s first ever science observing sea- worked together with the PIs and expert based facilities or in theory/modelling, son. In Cycle 0, data were observed and staff at the Joint ALMA Observatory (JAO) emphasising the diversity of the ALMA processed on a “best effort” basis since, in Chile and the ALMA Regional Centres community. during this observing season, many (ARCs), making sure that all Phase II future capabilities still had to be commis- material was technically feasible and in More than 75% of the users who worked sioned, new antennas integrated into agreement with the science goals. After with ALMA data considered their quality the array and software and procedures execution of the projects, the data went above average. Remarkably, only 48% still needed to be tested. Despite these through a series of quality assurance indicated that they used the ALMA data constraints, it is very gratifying that of the steps, the last one being full calibration analysis package CASA to reduce their 113 highest priority projects selected for of the data and the creation of datacubes data, emphasising the need to offer more the first Cycle, 94% were fully or partially or images. Gaining experience through- data reduction workshops to the com observed, 35 of which were led by Euro- out the cycle, the time between data- munity. The high quality of the European pean principal investigators (PIs). At the taking and delivery to the PI dropped to support structure was also acknow time of writing, 26 of these European-led approximately one month by the end of ledged: from the users who visited an projects have been fully observed and Cycle 0. ARC node for Cycle 0 data reduction, their quality assured, and the data have 93% considered the quality of support been delivered to the PIs. Of the other above average. The experience with the nine projects that were not fully observed, The European ARC nodes generation of Scheduling Blocks (SBs) the existing data have been partly deliv- was rated above average by 55% of ered. In summary, 35 European PIs have Throughout Cycle 0 it has become clear Cycle 0 users, but it should be noted that received Cycle 0 data thus far. that the European support structure the Observing Tool was still under active with a distributed network of ARC nodes development during Cycle 0. Support has worked extremely well. These local from the ARC contact scientists for gen- Cycle 0 science expertise centres provided support to eration of Cycle 0 SBs was rated above their communities by organising commu- average by 83% of the users. The first proprietary ALMA data were nity days, training sessions and science- delivered to users in all three executives oriented meetings, provided help with

20 The Messenger 151 – March 2013 Telescopes and Instrumentation

First Light for the KMOS Multi-Object Integral-Field Spectrometer

Ray Sharples1 Ralf Bender2, 5 Alex Agudo Berbel2 Naidu Bezawada3 Roberto Castillo4 Michele Cirasuolo3 George Davidson3 Richard Davies2 Marc Dubbeldam1 Alasdair Fairley3 Gert Finger4 Natascha Förster Schreiber2 Frederic Gonte4 Figure 1. The KMOS CACOR leaving the UK Astron- co-rotating structure, was too large to Achim Hess5 omy Technology Centre (left), and installed in its fit into any available air-freight carrier. This 4 open-top container ready for the sea journey to Ives Jung Paranal (right). large item was therefore securely packed Ian Lewis6 and made the slightly more perilous, Jean-Louis Lizon4 but more leisurely, journey on the open Bernard Muschielok5 KMOS is one of a suite of second gener- deck of a container ship (Figure 1). Fortu- Luca Pasquini4 ation VLT instruments which, along with nately both cargoes arrived without dam- Jeff Pirard4 MUSE (Bacon et al., 2012) and SPHERE age, more or less at the same time, at Dan Popovic4 (Kasper et al., 2012), will bring exciting the port in Antofagasta. KMOS then Suzanne Ramsay4 new capabilities to the Paranal Observa- made the final leg of the journey by road Phil Rees3 tory in next few years. KMOS is a unique to the new integration hall at the Paranal Josef Richter5 design of near-infrared multi-object spec- Observatory. Miguel Riquelme4 trograph that uses deployable integral Myriam Rodrigues4 field units to obtain spatially resolved KMOS was fully re-assembled and re- Ivo Saviane4 spectra for up to 24 target objects sel calibrated in the integration hall over Joerg Schlichter5 ected from within an extended 7.2-arc- an eight-week period in September– Linda Schmidtobreick4 minute diameter field of view (Sharples et November 2012 by a dedicated team Alex Segovia4 al., 2010). of technical experts from the UK and Alain Smette4 German consortium partners, working Thomas Szeifert4 In mid-2012, KMOS reached its Provi- closely with ESO personnel. After an Arno van Kesteren4 sional Acceptance Europe milestone extensive set of verification tests, the Michael Wegner5 (Ramsay, 2012) and then began its long instrument was then taken up the final Erich Wiezorrek2 journey to the summit of Cerro Paranal stretch of the mountain road at walking via a combination of road, sea and air pace (Figure 2, left), before being in- transport. Whilst the main cryostat could stalled on the Nasmyth platform of VLT 1 Department of Physics, University of be shipped in a Boeing 747 cargo hold, Unit Telescope 1 (Antu). Because of the Durham, United Kingdom the auxiliary CACOR unit, which carries size of the CACOR (about four metres 2 Max-Planck-Institut für extraterrestrische the KMOS electronics cabinets in a large high), this item had to be lifted directly Physik, Garching, Germany 3 UK Astronomy Technology Centre, Royal Observatory, Edinburgh, United Figure 2. KMOS cryostat on the road from the inte- Kingdom gration hall to the summit (left); the CACOR being hoisted into the dome of UT1 (right). 4 ESO 5 Universitätssternwarte München, Germany 6 Sub-Department of Astrophysics, University of Oxford, United Kingdom

The KMOS near-infrared multi-object integral-field spectrometer was trans- ported to Chile in the middle of 2012 and achieved its first views of the Paranal skies in November 2012. We describe the delivery and re-integration of KMOS and present the first results from the two on-sky commissioning runs.

The Messenger 151 – March 2013 21 Telescopes and Instrumentation Sharples R. et al., First Light for KMOS

Figure 3. Some of the in through the dome aperture using an commissioning team in external crane (Figure 2, right). the VLTI control room during the first night of observations with KMOS. Commissioning-1

First light with KMOS occurred on 21 November 2012. After a slightly cloudy start, the dome opened at 21:30 and the first targets were acquired. Initially this involved pointing the telescope at a relatively bright star and taking short exposures with one arm at a time placed at the centre of the field. Every single star appeared within the integral field unit (IFU) field of view of 2.8 × 2.8 arcseconds, much to the relief of the commissioning team (Figure 3)! Even this relatively simple

.6t+_Y .6t+_Y .6t+_Y .6t+_Y observation required a large number of systems to be working together, such as the real-time display, which shows the positions of the target objects in the reconstructed datacubes. This acquisi- BRDBNMCR l Q tion sequence is a key feature of KMOS l and allows the telescope pointing to be l refined by placing a subset of the pickoff arms onto bright targets, which are then centred automatically using a shift and rotation of the telescope field of view (in much the same way that bright reference

BRDBNMCR stars are used to align the slit masks in l Q the FORS2 spectrograph). Once the field l is aligned, these arms can then be rede- l ployed to science targets. l l l l l l l l l l l l QBRDBNMCR QBRDBNMCR QBRDBNMCR QBRDBNMCR One of the first issues to address there- Figure 4. (Top) Hα emission line maps (top) and data were obtained with only 30 minutes of on- fore was the astrometric positioning derived velocity fields (bottom) for a sample of faint source exposure using KMOS and demonstrate the of the arms; this included both the overall z ~ 1 emission-line galaxies in the GOOD-South power of this facility instrument for such surveys. field. The brightest targets have an observed inte- Reductions courtesy of Mark Swinbank. plate scale, and any radial variation at grated Hα flux of 1.0 × 10–16 ergs cm–2 s–1. These the arm focal plane(s), and also the local corrections (lookup tables) which are used to take out the individual variations in the movement of each arm. The latter stage was particularly troublesome, as it required an astrometric calibration pro- cedure to be set up on sky using densely populated star fields in open or globular star clusters. The final calibration was not

NTMSR achieved until Commissioning-2, but now B demonstrates that the arms have a final

1σ positioning accuracy of 0.1 arcseconds. The rest of the first commissioning run was taken up with exercising all the KMOS modes, including its unique capabilities to produce large mosaic patterns 6@UDKDMFSGƅL covering up to 60 by 40 arcseconds on the sky, and in obtaining calibration Figure 5. KMOS H-band spectrum of the B8 iii emis- and performance data to complete the sion line star Hip 022112 (HD 30123). verification tests (e.g., Figure 4).

22 The Messenger 151 – March 2013 Commissioning-2 Figure 6. Reconstructed spectral image of Jupiter (pseudo colours refer to The second commissioning run took narrow bands extracted place in the latter half of January 2013 from the spectrum to high- and, whilst not blessed with the same light various features). This level of clear skies as the first run, en image was created using the 24-arm mapping tem- abled the commissioning team to com- plate with non-sidereal plete a number of outstanding tests tracking and comprises and improve the integration with the VLT nearly 75 000 spectra. The control system. A further focus of the numbers refer to zones covered by specific IFUs during second run was to obtain some deep-sky the dithered pointings. observations with KMOS to evaluate the different modes of sky subtraction, and to fully test the KMOS data reduction pipeline SPARK (Davies et al., 2012). Cali- bration arc and flatfield exposures were taken automatically during the daytime at position angles close to those of the night’s observations; this step minimises the effects of instrument flexure on the wavelength accuracy. After calibration using the daytime arc exposures, the re maining shifts of the night-sky OH lines have a root mean square residual < 20 km/s; this can be reduced to < 5 km/s by application of a simple model of the flexure. Figure 5 shows a typical example spectrum of a bright emission- line star processed at the telescope using the default pipeline. Figure 7. KMOS K-band spectral images of R136 Some of the more visually impressive (30 Doradus). At top left is a narrowband image extracted from the datacube in the 2.1 μm continuum, capabilities of KMOS are the spectral at top right a narrowband image in Br-γ (2.16 μm) is images which can be produced using selected and at bottom is the image in He ii (2.19 μm) the mosaic mode in which the IFUs are with the position of a Wolf–Rayet star marked. packed into a regular grid pattern, with gaps which are then filled by offset pointings of the telescope. Two modes the instrument will be warmed up to fit are available: either using all 24 arms new dampers to the closed-cycle coolers (16 pointings) or a reduced mosaic of to minimise any vibration effects on the eight arms (nine pointings) if a faster cov- VLTI. Assuming this is successful, the first erage of a smaller area is required. All of regions of Brackett-γ emission and the community Science Verification observa- the o ffsetting and combining of the cubes He ii emission characteristic of massive tions may take place in summer 2013. is handled automatically by the templates Wolf–Rayet stars. The data for these We look forward to much exciting new and data pipeline. Figure 6 shows one commissioning observations are available science from KMOS in the next few years. of the early results obtained (using non- for download1. sidereal tracking) of an H-band mosaic of Jupiter. Although the full information References content of this observation (75 000 spec- Current status Bacon, R. et al. 2012, The Messenger, 147, 4 tra in total) cannot be gleaned from a Davies, R. et al. 2010, Proc. SPIE, 7735, 77356V simple two-dimensional picture, the col- The data from the first two commission- Kasper, M. et al. 2012, The Messenger, 149, 17 our scheme has been tuned to reveal ing runs are currently being fully reduced Ramsay, S. 2012, The Messenger, 149, 16 the spectral differences (mainly methane and analysed. During both observing Sharples, R. et al. 2010, The Messenger, 139, 24 bands) in the equatorial zones and the campaigns, the instrument has per- polar caps of the planet. Another exam- formed nearly flawlessly and it is offered Links ple is shown in Figure 7 for observations to the ESO community in the Call for 1 of 30 Doradus in the Large Magellanic Proposals for Period 92 (October 2013– Access to presented KMOS commissioning data: http://www.eso.org/sci/activities/vltcomm/ Cloud, where the cube has been sliced to March 2014). A final “Paranalisation” run kmos.html show the continuum in the K-band, is scheduled for March 2013, after which

The Messenger 151 – March 2013 23 Release eso1237. in details More nebula. the ionises HD 53367 star (B0) early-type bright, located, centrally BVR Imager Field Wide and telescope 2.2-metre MPG/ESO from composed H dusty the of Image Astronomical Science ii region 2-292 Sharpless and H and α images. The Astronomical Science

Boötes-I, Segue 1, the Orphan Stream and CEMP-no Stars: Extreme Systems Quantifying Feedback and Chemical Evolution in the Oldest and Smallest Galaxies

Gerard Gilmore1 function has been extended down to most enigmatic of the ultra-faint systems. Sergey Koposov1 luminosities three orders of magnitude These targets include: the lowest luminos- John E. Norris2 below previous limits in recent years. ity system Segue 1 (Belokurov, 2007a; Lorenzo Monaco3 Remarkably, these extremely low lumi- see Simon et al. [2011] for a detailed Keck David Yong2 nosity objects, the dwarf spheroidal study) and the Orphan stream (Belokurov Rosemary Wyse4 (dSph) galaxies with total luminosities as et al., 2007b), both of which are at similar 1 Vasily Belokurov low as 1000 LA, comparable to a moder- distances to the bifurcated tidal tail of Doug Geisler5 ate star cluster, are quite unlike star Sgr (Ibata, Gilmore & Irwin, 1994); the N. Wyn Evans1 clusters — they are real galaxies. Fortu- common-distance and similar-velocity Michael Fellhauer5 nately, with their very few red giants but pair Leo-IV and Leo-V (Belokurov et al., Wolfgang Gieren5 more populous main-sequence turn- 2008); and the inner regions of Boötes-I Mike Irwin1 off stars, they are within range of detailed (Belokurov et al., 2006b), a surviving ex Matthew Walker1, 6 study, with considerable efforts currently ample of one of the first bound objects Mark Wilkinson7 underway at the Very Large Telescope to form in the Universe, providing a touch- Daniel Zucker8 (VLT) and Keck. stone to test the chemical evolution of the earliest low-mass stars. These lowest-luminosity galaxies provide 1 Institute of Astronomy, Cambridge, a unique opportunity to quantify the Our FLAMES GIRAFFE and UVES spec- United Kingdom formation and chemical enrichment of the tra are beginning to quantify the kine 2 Mount Stromlo Observatory, Australian first bound structures in the Universe. matics and abundance distribution func- National University, Canberra, Australia At present, there are no convincing mod- tions in these systems, including several 3 ESO els for the origin and evolution of these element ratios, providing the first quan 4 Johns Hopkins University, Baltimore, extreme objects — observations lead the titative study of what we find to be survi- USA way. The ultra-faint dSphs certainly have vors of truly primordial systems that 5 Departamento de Astronomia, extreme properties. They are clustered in ap parently formed and evolved before the Universidad de Concepcion, Chile groups on the sky, their velocity disper- time of reionisation. Our target fields are 6 Harvard University, Cambridge, USA sions are tiny — no more than 3–4 km/s summarised in Figure 1. 7 University of Leicester, Leicester, United at the lowest luminosities — yet the ob Kingdom jects themselves are very extended, with 8 Macquarie University, Sydney, Australia half-light radii of hundreds of parsecs, Segue 1 and the Orphan Stream implying extreme dark matter dominance. Their chemical abundances are also Segue 1 is the lowest luminosity galaxy Galactic satellite galaxies provide a extreme, with dispersions of several dex, known. It has a wide abundance range, unique opportunity to map the history and containing stars down to [Fe/H] = –4. including hosting a very carbon-enhanced of early star formation and chemical There are hints that they are associated metal-poor star with no enhancement evolution, the baryonic feedback on gas with, or possibly entangled in, kinematic of heavy neutron-capture elements over and dark matter, and the structure of streams and superimposed on — or in — Solar ratios (called a CEMP-no star: c.f., low-mass dark matter halos, in surviv- the tidal tails of the more luminous Sagit- Norris et al. [2010a] for our VLT study and ing examples of the first galaxies. We tarius dSph (Sgr) galaxy. Beers & Christlieb [2005] for the defini- are using VLT–FLAMES spectroscopy tions of metal-poor star subclasses). Such to map the kinematics and chemical The lowest luminosity dSphs do not look stars, which are like those in the Milky abundances of stars in several ultra- like the tidal debris of larger systems, Way Halo field, are suspected to be suc- faint dwarf spheroidal galaxies and the they look like the most primordial galax- cessors of the very first supernovae — enigmatic Orphan Stream in the Halo. ies of all. Arguably even more interesting see below. The velocity distribution Two paths of early chemical enrichment than their relevance as galaxy building measured in Segue 1, which is consistent at very low iron abundance are observed blocks is to understand the objects them- with the Keck study of Simon et al. (2011), directly: one rapid and carbon-rich selves. Are they the first objects? Did they shows a very narrow distribution, consist- (CEMP-no), one slow and carbon-nor- contribute significantly to reionisation? ent with a dispersion of less than 4 km/s. mal. We deduce long-lived, low-rate What do they tell us of the first stars? In spite of this low dispersion, Segue 1 is star formation in Boötes-I, implying What was the stellar initial mass function completely dark-matter dominated, with insignificant dynamical feedback on the (IMF) at near-zero metallicity? How are a mass-to-light ratio in excess of 1000. structure of its dark matter halo, and the faintest dSphs related to more lumi- The velocity distribution function, in which find remarkably similar kinematics in the nous dSphs and the Milky Way galaxy? Segue 1 has its radial velocity near apparently discrete systems Segue 1 V = 200 km/s, also indicates the pres- and the Orphan Stream. In order to address these questions, we ence of stars from the Sagittarius tidal are obtaining VLT FLAMES observations stream (at V = 0 km/s), which is at a very using both the spectrographs GIRAFFE similar distance, and stars in a cold With the discoveries from the Sloan and UVES, with exposures of up to more kinematic structure with radial velocity Digital Sky Survey, the galaxy luminosity than 15 hours, of member stars of the V = 300 km/s. This cold highest-velocity

The Messenger 151 – March 2013 25 Astronomical Science Gilmore G. et al., Boötes-I, Segue 1, the Orphan Stream and CEMP-no Stars

Figure 1. The background shows the “Field of Streams” (Belokurov et al., 2006a), the distribution of turn-off stars observed by the Sloan Digital Sky Survey, statistically colour-coded by distance with the bluer colour showing more nearby, the redder more distant streams. The fields observed for this project by the VLT are marked in grey, with representative velocity distributions indicated. The @S HNM velocity distribution for Boötes-I is marked by its extreme narrowness.

#DBKHM The low surface brightness Orphan V 6WUHDP Stream is very evident in velocity space, again with very low velocity 6HJXH %RÓWHV, dispersion. Segue 1 shows three distinct velocity peaks, corresponding 0RQRFHUR to the Sgr Stream, Segue 1 itself, and 6DJLWWDULXV6WUHDP the “300 km/s” stream, evident only in /HR,9 2USKDQ 6WUHDP velocity space.

l 1HFGS@RBDMRHNM stream is not yet well defined, and remains pens to be passing through a busy part 240 pc), at 60 kpc Galactocentric dis- under study. of the outer Galaxy. The metal-poor tance, whose special features are its ([Fe/H] = –3.5) CEMP-no star Segue 1-7, low surface brightness and low total lumi-

The Orphan Stream provides another which we have studied with the VLT, nosity (Mv = –6). Boötes-I has low mean example of a Halo stream, although in lies almost four half-light radii from the metallicity (with a range from [Fe/H] = this case it has a sufficiently high surface centre of Segue 1, while all the other well- –3.7 to –1.9) and hosts a CEMP-no star brightness to allow it to be traced over studied members are inside 2.3 half- that we have studied with the VLT more than 60 degrees of arc. The peri- light radii (70 pc). Does this hint at tidal ([Fe/H] = –3.3; Norris et al., 2010b). Our galacticon of the Orphan Stream orbit truncation of an earlier, much larger (and GIRAFFE s pectra have been analysed for passes close to Segue 1, and hence to more luminous?) predecessor? Segue 1 a kinematic study (see Koposov et al., the Sagittarius tidal tail. As Figure 1 illus- is very deep inside the Galactic tidal 2011). Using careful data reduction tech- trates, the internal velocity dispersion field, well inside the (disrupting) Sgr dSph, niques, Koposov et al. (2011) showed in the Orphan Stream is unresolved at the and the Large Magellanic Cloud–Small that GIRAFFE spectra obtained in single resolution of the observations, being Magellanic Cloud pair, with their gaseous one-hour observing blocks over several less that 3–4 km/s. The Orphan Stream tidal stream. All the dSph galaxies that years can be combined to deliver radial and Segue 1 kinematics and distance, are not deep in the Galactic tidal field velocities with an accuracy floor ap the latter determined from main-sequence have much larger half-light radii (Gilmore proaching 0.1 km/s. From this study we turn-off fitting, provide an interesting et al., 2007). We also have the remarka- demonstrated that Boötes-I has a smaller illustration of the complexity of the outer ble similarity (indeed, near identity) of the velocity dispersion than suggested Galactic Halo. Both Segue 1 and the distances and radial velocities of Segue 1 by previous studies. We showed the kine- Orphan Stream have similarly low internal and the Orphan Stream as further clues. matics to be best described by a two- velocity dispersions. Remarkably, at the In spite of searching, we have not (as yet) component system, a majority with dis- Orphan Stream’s closest approach to found any trace of any extra-tidal Segue 1/ persion 2.5 km/s, and a minority with Segue 1, both have the same Galacto- Orphan Stream member stars, or a dispersion as high as 9 km/s, or by a sin- centric distance (within uncertainties), physical link between the systems: there gle dispersion of 4.6 km/s. Our pre- which is also the same as the local Sagit- are no identified stars with appropriate ferred interpretation is that the apparent tarius tail, being separated by only a few velocities in the spatial region between multi-component kinematic structure kiloparsecs (kpc) at most. Even more the Orphan Stream peri-galacticon and may reflect orbital anisotropy inside bizarrely, at the point of closest approach, Segue 1. Are they just ships passing Boötes-I. Our observations to date are the orbit of the Orphan Stream has in the dark night? The hunt for enlighten- limited to the central regions, so further exactly the same Galactocentric radial ment continues. study at larger radii is required to clarify velocity as does Segue 1. Is this coinci- the situation. dence, or evidence of a common history? Boötes-I There are key issues in early galaxy The analysis of Simon et al. (2011) sug- evolution which can be resolved by the gests that Segue 1 is contained inside Boötes-I provides an example of a comp analysis of chemical element distribu- its tidal radius, and is a robust, albeit lementary case: an apparently normal, tions. These include the early stellar high- small and faint, galaxy, which just hap- extended dSph galaxy (half-light radius mass IMF, star formation rates at very

26 The Messenger 151 – March 2013 a) b) Figure 2. A schematic diagram of the two star for- 1 - FIRST GENERATION SUPERNOVAE 2 - SECOND GENERATION STARS Carbon-rich branch mation and evolutionary paths evident at the lowest First SNe First SNe abundances. The very first stars, apparently of high +3 Carbon-rich +3 Carbon-rich Efﬁcient cooling mass, generate two patterns of chemical enrichment Star formation & SNe ejecta o ejecta — carbon-enhanced and carbon-normal (Figure 2a). o ati ati This difference may correspond to different progeni- n r n r → tors, or may simply be spatial inhomogeneity from ro ro /i

n/i a single SN. The carbon-enhanced material very rapidly cools, apparently forming stars with a wide

Carbo range of masses, including SN progenitors, which First SNe Carbon First SNe 0 C-normal 0 C-normal generate standard Galactic Population ii abundances ejecta ejecta (Figure 2b). This process continues until the carbon abundance in the ISM is diluted to the Solar value, Iron/hydrogen ratio Iron/hydrogen ratio when [Fe/H] ~ –3. The lower carbon abundance ISM –5 –3 –1 –5 –3 –1 does not take part in this enrichment process, but on a slower timescale stars are formed, again with a wide range of masses and an apparently standard IMF (Figure 2c). This enrichment path also eventually c) d) 3 - SECOND GENERATION STARS 4 - THIRD GENERATION STARS reaches [Fe/H] = –3. The whole ISM is now suffi- Carbon-poor branch ciently enriched for efficient cooling, so that chemi- First SNe First SNe cal evidence of the evolutionary path is now lost +3 Carbon-rich +3 Carbon-rich (Figure 2d). Should either path correspond to suffi- ejecta ejecta o o ciently slow star formation, SNe Type i a will generate ati rati low [ /Fe] at this stage. The correspondence of this n α n r ro ro model with data from stars in Boötes-I (circles) and /i /i Segue 1 (triangles) is shown in Figure 2e. Efﬁcient cooling AGB carbon; Carbon Carbon First SNe First SNe Inefﬁcient slow cooling; SN I a Fe production? 0 C-normal 0 C-normal late star formation and SNe ejecta ejecta significant in our present sample. The

Iron/hydrogen ratio Iron/hydrogen ratio observed lack of scatter in these ele- –5 –3 –1 –5 –3 –1 ment ratios at a given [Fe/H] requires that: (i) the stars formed from gas that was enriched by ejecta sampling the e) Bootes-1 STARS mass range of the progenitors of core- collapse supernovae (SNe); (ii) the supernova progenitor stars formed with an 2 +3 IMF similar to that of the Solar neighbour- hood today; and (iii) the ejecta from all o C-rich fast cooling ati 1 SNe were efficiently well-mixed. Both the e] n r first and last points set an upper limit [C /F on how rapidly star formation could have

bon/i ro 0 proceeded, since: the star formation re gions need to populate the entire massive- Car C-poor slow cooling 0 star IMF, the stars need sufficient time –1 to all explode, and the gas needs time to –4 –3.5 –3 –2.5 –2 –1.5 [Fe/H] mix the ejected enriched material. All Iron/hydrogen ratio these steps must occur before substan- –5 –3 –1 tial numbers of low-mass stars form.

The observed lack of scatter in the early times, and their consequences, and Enhanced ratios of α-element/Fe above α-element abundance ratios requires that feedback on baryonic gas and the dark the Solar values are expected in stars the well-sampled IMF of core-collapse matter potential well. Our UVES observa- formed from gas that is predominantly supernova progenitors is invariant over tions of Boötes-I address these points enriched by these endpoints of massive the range of time concerned and/or the directly (Gilmore et al., 2013). stars. Thus chemical abundances in iron abundance. This can be expressed the stars formed within the first 0.5 Gyr as a constraint, from the scatter, on the after star formation began will reflect the variation in slope of the massive star α-elements and the IMF products of predominantly core-collapse IMF, assuming that the ratios reflect IMF- supernovae. averaged yields. A scatter of 0.02 dex The α-elements, together with a small constrains the variation in IMF slope to be amount of iron, are created and ejected Although we see hints of a declining 0.2. The overall agreement between the by core-collapse supernovae, on time- α-element abundance, suggestive of a values of the elemental abundances in scales of less than 108 years after the for- resolution of the duration of the chemical Boötes-I stars and in the field of the Halo mation of the supernova progenitors. evolution of Boötes-I, this is not formally implies the same value of the massive

The Messenger 151 – March 2013 27 Astronomical Science Gilmore G. et al., Boötes-I, Segue 1, the Orphan Stream and CEMP-no Stars

star IMF that enriched the stars in each of Given the amplitude of the [C/Fe] and essentially primordial initial abundances. the two samples, although our formal [Mg/Fe] values in CEMP-no stars, one This allows us uniquely to investigate the limit on this IMF slope is only agreement must also explain why stars are not found place of CEMP-no stars in a chemically within a slope range of 1. with intermediate C and Mg excesses at evolving system, as well as to limit the higher [Fe/H]. Apparently the highly C- timescale of star formation in this dSph. The Galactic Halo and Boötes-I (and and Mg-enriched ISM does not survive to The low elemental abundance scatter Segue 1) display a large range in carbon mix with “normal” enriched ISM and form requires low star formation rates, allowing abundance at low metallicity. For iron more stars with moderate CEMP-no time for SNe ejecta to be created and abundances greater than about enrichment. Rather, the cooling efficiency mixed over the large spatial scales rele- [Fe/H] = –3.2, excess carbon enhance- of the highly carbon-enriched material vant. This is further evidence that B oötes-I ments above the solar [C/Fe] ratio are must be sufficiently great that all of it survived as a self-enriching star-forming consistent with carbon production in cools and forms (the surviving) low-mass system from very early times. It also asymptotic giant branch (AGB) compan- stars mixing with “normal” SNe ejecta im plies that only unimportant amounts of ions (called CEMP-r/s stars, which have before [Fe/H] reaches –3 dex. That is, our dynamical feedback between the star apparent contributions of both rapid (r) Boötes-I data provide direct evidence for formation in Boötes-I and its dark matter and slow (s) nucleosynthetic processes; two discrete channels of chemical enrich- halo can have occurred. Boötes-I is Beers & Christlieb, 2005). At lower values ment at very low iron abundances. indeed a surviving primordial system, of [Fe/H], excess carbon is commonly ideal to investigate the earliest stages of seen, but is inconsistent with AGB pro- With our current knowledge of stars in star formation, chemical enrichment and duction: rather the CEMP-no stars are Boötes-I, there is no direct chemical dark matter properties. more likely to have formed from gas evolution track (assuming standard yields enriched by non-standard supernovae of carbon and iron) between the CEMP- (such as “mixing and fallback” super no stars and the carbon-normal stars Acknowledgements novae), or by the winds from rapidly rotat- with [Fe/H] < –3. This means that at very Based on data obtained under ESO programmes: ing massive stars. In both cases the low iron abundance there is no one-to- P182.B-0372; P383.B-0038; P383.B-0093; supernova progenitors were massive one relationship between [Fe/H] and the P185.B-0946. Data-taking completed in P89. D. G. stars formed from primordial material — time since the first SNe. This conclusion & W. G. gratefully acknowledge support from the the first stars. is summarised in Figure 2, which shows Chilean BASAL Centro de Excelencia en Astrophys- ica y Technologias Afines (CATA) grant PFB-06/2007. the chemical evolutionary enrichment J. E. N. and D. Y. acknowledge support by Australian sequence deduced from our UVES study, Research Council grants DP0663562 and CEMP-no stars and its consistency with observations. DP0984924. R. F. G. W. acknowledges partial sup- The CEMP-no stars form rapidly out of port from the US National Science Foundation through grants AST-0908326 and CDI-1124403, and Our discovery of CEMP-no stars in the gas enriched by only one generation of thanks the Aspen Center for Physics (supported by two dwarf galaxies Segue 1 and Boötes-I SNe and most likely prior to the onset of NSF grant PHY-1066293) for hospitality while this is strong evidence for their self-enrichment effective mixing. This results in a small work was completed. from primordial material. The carbon mixing length, spatial inhomogeneity and over-abundance reflects the yields of the a large scatter in elemental abundance References very first generation of supernovae or ratios. massive stars. This provides an oppor Beers, T. C. & Christlieb, N. 2005, ARAA, 43, 531 tunity to consider the evolutionary history Such a scenario requires that the gas Belokurov, V. et al. 2006a, ApJ, 642, L137 Belokurov, V. et al. 2006b, ApJ, 647, L111 of the extremely carbon-enriched, iron- within which the CEMP-no stars form can Belokurov, V. et al. 2007a, ApJ, 654, 897 poor interstellar medium gas in these gal- cool and be locked up in low-mass stars Belokurov, V. et al. 2007b, ApJ, 658, 337 axies. very rapidly, and with high efficiency, so Belokurov, V. et al. 2008, ApJ, 686, L83 that material with this abundance pattern Caffau, E. et al. 2011, Nature, 477, 67 Gilmore, G. et al. 2007, ApJ, 663, 948 A key piece of information is that the is removed from the system at early times. Gilmore, G. et al. 2013, ApJ, 793, 61 most iron-poor star currently known This picture is consistent with models Ibata, R., Gilmore, G. & Irwin, M. 1994, Nature, in Boötes-I is not carbon-enhanced. of the formation of very metal-poor low- 370, 194 Carbon-enhanced and carbon-normal mass stars which appeal to enhanced Koposov, S. et al. 2011, ApJ, 736, 146 Norris, J. E. et al. 2010a, ApJ, 722, L104 stars co-exist at the same low iron cooling due to carbon. It may well be that Norris, J. E. et al. 2010b, ApJ, 711, 350 abundance within the same system (and the CEMP-no material resulted from a Norris, J. E. et al. 2013, ApJ, 762, 28 in the Galactic field Halo; c.f. Caffau et very small number of (Population III?) Simon, J. et al. 2011, ApJ, 733, 46 al., 2011). This provides direct evidence supernovae, possibly only one. that carbon enhancement is not required for very low-iron abundance gas to cool and form low-mass stars. The additional A surviving primordial galaxy information we consider here is that CEMP-no stars are not found at [Fe/H] Our metallicity and elemental abundance greater than –2.5, either in the field Halo data show that Boötes-I has evolved as or in dwarf spheroidal galaxies. a self-enriching star-forming system, from

28 The Messenger 151 – March 2013 Astronomical Science

SUDARE at the VST

Maria Teresa Botticella1 events, suggest the existence of an unex- stars in binary systems losing the largest Enrico Cappellaro2 pected SN diversity (Benetti et al., 2005), fraction of their initial mass. Giuliano Pignata3 which is difficult to explain within the Andrea Baruffolo2 standard scenarios. With the goal of Concerning SNe i a, there is general Stefano Benetti2 achieving a better insight into the physics consensus that they correspond to Filomena Bufano3 of SN progenitors of all different flavours, thermonuclear explosions of a carbon Massimo Capaccioli4 we have started the SUDARE programme and oxygen white dwarf (WD) which Enrico Cascone1 which is currently running at the VLT Sur- reaches the Chandrasekhar mass due Giovanni Covone4 vey Telescope (VST). to accretion from a close companion. Massimo Della Valle1 Two kinds of evolutionary paths for the Aniello Grado1 progenitors are mostly considered in Laura Greggio2 Background: SNe as fascinating tran- the literature: a) the single degenerate Luca Limatola1 sients scenario, in which a WD, accreting from Maurizio Paolillo4 a non-degenerate companion (a main Andrea Pastorello2 SNe are energetic explosions related to sequence star, a red giant or a helium Lina Tomasella2 some of the most important problems star), grows in mass until it reaches the Massimo Turatto2 of modern astrophysics. They are one of Chandrasekhar limit; b) the double degen- Mattia Vaccari5 the more promising tools to probe the erate scenario, in which a close double nature of dark energy in the Universe and WD system merges after orbital shrinkage provide a natural laboratory for studying due to the emission of gravitational waves. 1 INAF–Osservatorio Astronomico di the physics of hydrodynamic and nuclear If the total mass of the system reaches Capodimonte, Italy processes under extreme conditions. the Chandrasekhar limit, carbon ignition 2 INAF–Osservatorio Astronomico di SNe are involved in the formation of neu- under degenerate conditions may produce Padova, Italy tron stars, black holes, and gamma- a Type i a SN explosion. 3 Departemento de Ciencias Fisicas, ray bursts and are sources of neutrino Universidad Andres Bello, Chile emission, high-energy cosmic rays and 4 Dipartimento di Fisica, Universita gravitational waves. The energy release Motivations: SN progenitors and the Federico II, Italy from SNe can trigger episodes of star nature of SN diversity 5 Physics Department, University of the formation (SF), impacting the evolution of Western Cape, South Africa gas flows and contributing to the feed- The current picture of the death of mas- back processes in galaxies. They are also sive stars is far from clear and several the main producers of heavy elements important questions, such as what is the The SUpernova Diversity And Rate and are fundamental for modelling the mass range of the progenitor stars of dif- Evolution (SUDARE) programme on the chemical evolution of galaxies and abun- ferent CC SN sub-types and what are the VLT Survey Telescope aims to collect dance patterns in clusters of galaxies. effects of rotation, metallicity and binary an unbiased and homogeneous sample Moreover, the metal-rich ejecta of SNe evolution on these mass ranges, still of supernovae (SNe) in all types of gal- are believed to be potentially important await answers. The simple scheme where axies out to redshift ~ 0.6. In four years, sites of cosmic dust formation. only mass loss drives the evolution of around 500 Type i a and core-collapse massive stars has difficulties in explaining SNe are expected to be discovered, We recognise two physically different the wide range of properties shown by including significant numbers of rare SN classes of SNe: core-collapse induced CC SNe of the same type and the relative types. The programme is outlined and explosions of short-lived massive stars frequencies of the different types (ii P 69%, 100 SNe candidates have already been (CC SNe) and thermonuclear explosions ii b 12%, ii n 9% and ii L 10% of all Type ii; detected in the first year of the proof long-lived low-mass stars (SNe i a). i b 22%, i c 54% and 24% peculiar events gramme. Follow-up spectroscopy of the All stars more massive than about eight of all Type i bc; Li et al., 2011). SN candidates, an important aspect solar masses develop an iron core that of the programme, is also described. cannot be supported by any further The direct detection of the SN progenitor nuclear fusion reaction, or by electron on pre-explosion images provides a degenerate pressure, and hence collapse robust mapping between the progenitor Despite the key role played by super to form a neutron star or a black hole. stars and their explosion, but requires novae in discovering the accelerating Different sub-types of CC SNe have been high resolution and deep pre-explosion expansion of the Universe (Perlmutter et identified on the basis of their spectro- images, so that reliable results are avail al., 1998; Riess et al., 1998) there are scopic and photometric properties (ii P, able only for a dozen nearby SNe (Smartt still basic questions to answer about SN ii L, ii n, ii b, i b, i c; see Turatto et al., 2003). et al., 2009). The nature of the SN i a progenitors and explosion mechanisms. These subtypes have been associated progenitor system and the details of the Furthermore the discovery of a growing with a possible sequence of progenitor explosion mechanisms are thus still number of exceptionally bright and characteristics related to mass-loss his- debated. extremely faint SNe, as well as peculiar tory, with the most massive stars and

The Messenger 151 – March 2013 29 Astronomical Science Botticella M. et al., SUDARE at the VST

The use of SNe i a as standard candles Figure 1. The number of expected is based on the assumption that all ( @ SNe discovered by SUDARE in CDFS "" (200 SNe of which 25% CC SNe) as SNe i a are highly homogeneous (at dif a function of redshift. The blue (red) ferent cosmic epochs). However, in histogram shows the Type i a SNe the last few years spectroscopic and (CC SNe) with spectroscopic classifi- photometric peculiarities have been cation discovered in the first season. noted with increasing frequency (about AHM

50%) and new subclasses of SNe i a ES

have been introduced (20% with high CRGH expansion velocities, 10% as SN 1991bg- QD

like objects, 15% as SN 1991T-like D

ob jects, 5% as 2002cx-like objects; see 2- Li et al., 2011). Whether these subclasses form distinct physical groups from normal SNe i a, with different progenitors and explosion mechanisms, or whether they lie at the extreme end of a continuous distribution, is still unclear. In this framework, the relationship 1DCRGHES between SN properties and the parent stellar populations can help constrain the progenitors and hence deepen Similar considerations hold for the cosmic optics, offers an unprecedented oppor understanding of the origin of the diver- SN i a rate in relation to the cosmic SFR. tunity for an SN search in the redshift sity. In particular, the simultaneous analy- range 0.3 < z < 0.6. This redshift range is sis of the cosmic evolution of SN rates crucial to connect measurements from and the dependence of SN rates on A new SN search past SN surveys in the nearby Universe some host galaxy properties is a power- and the future high-redshift surveys ful diagnostic tool to investigate the Our efforts to investigate the cosmic like the Dark Energy Survey (DES) or, in effects of age, environment and metal evolution of SN rates began a decade the longer term, with facilities such as the licity on the SN progenitors and their ago with a SN search exploiting the Large Synoptic Survey Telescope (LSST) diversity. For example, it appears that Wide Field Imager (WFI) at the 2.2-metre and the ESA Euclid satellite mission. subluminous SNe i a preferably occur MPG/ESO telescope. The Southern in massive non-star-forming host galax- inTermediate Redshift ESO Supernova Detailed simulations assuming the VST ies, while super-luminous SNe i a occur Search (STRESS) discovered 86 SNe performance and the observational in relatively metal-poor host galaxies. (nine SNe i a and 16 CC SNe with spec- strategy of SUDARE show that we should troscopic classification) during 16 ob discover about 500 SNe, of which 25% Taking into account the short lifetime of serving runs distributed over a period of are expected to be CC SNe (Figure 1) by massive stars, the CC SN progenitor six years (from 1999 to 2005; Cappellaro the end of a four-year programme. The scenarios can be probed by comparing et al., 2005). We found that the CC SN size of this SN sample is suitable both for the star formation rate (SFR) and the rate rate is already higher by a factor of two the measurement of the rate of all SN of CC SNe in the same galaxy sample, with respect to the local value by redshift sub-types and to discover rare types of assuming the distribution of the masses z = 0.2, whereas the SN i a rate remains SN explosions. Indeed the depth of with which stars were born, i.e. the initial almost constant. This finding implies that SUDARE images allows us to exploit, mass function (Botticella et al., 2012). a significant fraction of SN i a progeni- during each epoch, a volume of space On the other hand, the SN i a rate echoes tors have a lifetime longer than 2–3 Gyr that is about 1000 times larger than the whole star formation history of the ( Botticella et al., 2008). However, the that sampled by nearby SN surveys and host galaxy due to the time delays SN sample collected from STRESS was thus is more suitable to discover rare between the birth of an SN i a progenitor not large enough to perform a statistically and peculiar events. Given an observed and its death. By comparing the observed significant investigation of the SN diversity. rate of peculiar SNe of the order of 5% SN i a rate in different galaxy types with of “standard” CC and SN i a rates, we that expected for the star formation Therefore we decided to contribute to the expect, by the end of our programme, to history of the parent galaxy population, it international consortium for the delivery have detected about two dozen of such is possible to constrain the distribution of OmegaCAM and the VST telescope “weird” stellar explosions. of the delay times (Greggio, 2010). In turn, (Capaccioli & Schipani, 2011; Kuijken, this allows us to test the progenitor sce- 2011). The wide field of view and high The novelty of SUDARE is the emphasis narios, which predict different fractions of spatial resolution of OmegaCAM , jointly that we put on the analysis of the binaries exploding with different delays. with the excellent quality of the VST parent stellar population, with the aim of

30 The Messenger 151 – March 2013 constraining the SN progenitors and long-term monitoring of the selected sky investigating a possible evolution of SN fields, in the r- (with a cadence of 2–4 diversity with cosmic time. Our goal of days), g- and i-bands (with a cadence of measuring SN rates as a function of gal- one week) to a limiting magnitude of axy age, mass, SFR, metallicity and in 25 mag. In order to reduce the possible different environments requires a detailed effects due to cosmic variance, the characterisation of the galaxy sample pointing will change by one degree from surveyed. We therefore decided to search season to season so that, by the end for SNe in two sky fields: the Chandra of the survey we will have covered two Deep Field South (CDFS) and the Cosmic square degrees both for the CDFS and Evolution Survey (COSMOS) field. These COSMOS fields. fields have an extraordinary amount of ancillary data from X-ray to radio wave- The transients are detected in the r-band lengths (e.g., the GALEX Deep Imaging on difference images obtained by sub- Survey in the ultraviolet, the VISTA– tracting from a given image a template VIDEO ESO public purvey in the near- image acquired at a different epoch (see infrared, the Spitzer–SERVS and Spitzer– Figure 2 for some examples). The mag SWIRE Surveys in the mid- to far-infrared, nitude limit in the difference image is the Herschel–HerMES Survey in the far- about 24 mag depending on the quality infrared and submillimetre, and the ATCA– of the search image and the brightness of ATLAS Survey in the radio) that will allow the host galaxy in the transient location. us to retrieve important properties of Images in g- and i-bands will provide col- the surveyed galaxies, including redshift, our evolution for each transient. A rolling luminosity, morphology, star formation search secures photometric typing for history and mass. each transient that will be validated by spectroscopic classification for a fraction In addition, the VST–Optical Imaging of (30%) of the SN candidates, obtained CDFS and ES1 (VOICE) survey (PIs G. through dedicated programmes at Covone and M. Vaccari) is observing 8-metre-class telescopes such as the CDFS in the u-band and obtaining addi- VLT, Magellan and Gemini South. tional g-, r- and i-band images to improve the accuracy of the photometric A key feature of our strategy is the very redshifts and to estimate galaxy stellar rapid turnaround from observation to masses, SFRs and environmental proper- transient detection. This can be accom- ties. The COSMOS field will be also plished because of the excellent services monitored over the next five years in the offered by ESO, beginning with service Y-, J-, H- and Ks-bands to unprecedented observing mode, which is crucial for our depth by the UltraVISTA ESO public sur- programme. This is accompanied by vey. It will be very interesting to compare real-time archive ingestion and delivery the optical and near-infrared SN rates in along with access to a mature tool for the same galaxy sample up to redshift VST data reduction (VST-Tube; Grado et 0.3–0.4. This comparison will allow us to al., 2012). As a result we are in the posi- estimate the fraction of missed SNe in tion to obtain spectroscopic classification the optical search due to dust extinction. for transient events within 24 hours of An important by-product of our search their detection. will be the detection of the variability of active galactic nuclei (AGNs) and the gathering of their optical light curves. The first SNe are coming out ... and it is only the beginning!

Observational strategy SUDARE started on 20 October 2011 and has imaged CDFS in 55 epochs The strategy of the SUDARE survey has (ESO Periods 88, 89 and 90) exploiting been tuned to collect an unbiased and VST and OmegaCAM guaranteed Figure 2. Search image (left panel), template image homogeneous sample of all SN types in observing time (PI Cappellaro) and (centre panel), and difference image (right panel) an unbiased galaxy sample. We are per- imaged the COSMOS field in 30 epochs for the ten SUDARE SNe with spectroscopic classifi cation. forming a “rolling search”, a frequent, (ESO Period 88: PI Pignata). So far we

The Messenger 151 – March 2013 31 Astronomical Science Botticella M. et al., SUDARE at the VST

have discovered a hundred SN candi- 2- FR dates, several variable AGNs and a num- FR ber of variable stars. In three different (@# nights we obtained spectroscopic clas sification for a dozen of the SN candidates at the VLT, equipped with the FOcal

Reducer and low dispersion Spectro- Ä F F

graph and at Gemini-South, equipped DQ W with the Gemini Multi-Object Spectro- Q L@ graph. These SNe are reported in the %KT Central Bureau for Astronomical Tele- grams (CBET) 3236, 3274, 3311. Six of these SNe are Type i a with an average redshift of 0.5 (Figure 3 shows the light curve and spectrum of one example, SN 2012gs at z = 0.52), two are Type i c (Figure 4 shows the light curve and ,)#l 6@UDKDMFSGÄ spectrum of SN 2012fn, a Type i c at z = 0.28) and two are Type ii in a redshift Figure 3. Light curve and spectrum of SN 2012gs, a range from 0.3 to 0.6. Classifications Type i a at z = 0.52 discovered by SUDARE. The green spectrum is the best-fit template obtained by were performed with the GELATO tool GELATO. ( Harutyunyan et al., 2008).

Four transients were discovered within 0.1 arcseconds from the host galaxy 2- EM nuclei and all exhibited the spectrum of EM (B IC a Seyfert galaxy. All the SNe were discovered well before maximum light thanks to the temporal cadence of our survey that allows both an early discovery and an optimal photometric coverage. Ä F F

The distribution in redshift, magnitude DQ

and SN type of this subsample with Q L@ spectroscopic classification is in excellent %KTW agreement with that expected from our simulations (Figure 1).

The first systematic SN search began about 80 years ago by F. Zwicky at Mount Palomar with a Schmidt telescope (with a field of view of several degrees) ,)#l 6@UDKDMFSGÄ equipped with photographic plates. SN candidates were searched for by scan- Figure 4. Light curve and spectrum of SN 2012fn, a ning by eye two overlapped plates Type i c at z = 0.28 discovered by SUDARE. The green spectrum is the best-fit template obtained by acquired on different nights, and over a GELATO. thousand images were inspected to find only a dozen SNe. In a single image of OmegaCAM with SUDARE, the improved magnitude limit now allows us to detect SUDARE (in Italian this word means “to Cappellaro, E. et al. 2005, A&A, 430, 83 the same number of SNe. This extra exude sweat”) would have been more Grado, A. et al. 2012, MSAIS, 19, 362 Greggio, L. 2010, MNRAS, 406, 22 ordinary improvement is due to modern appropriate for Zwicky’s survey. Harutyunyan, A. et al. 2008, A&A, 488, 383 CCD mosaic cameras, adaptive optics Kuijken, K. 2011, The Messenger, 146, 8 and the subtraction process of digital Li, W. et al. 2011, MNRAS, 412, 1441 images, allowing us to discover faint tran- References Perlmutter, S. et al. 1998, Nature, 391, 51 Riess, A. et al. 1998, AJ, 116, 1009 sients also in distant galaxies. The Benetti, S. et al. 2005, APJ, 623, 1011 Botticella, M. T. et al. 2008, A&A, 479, 49 Smartt, S. J. et al. 2009, MNRAS, 395, 1409 authors of this paper consider it a privi- Botticella, M. T. et al. 2012, A&A, 537, 132 Turatto, M. et al. 2003, ESO Astrophysics Symposia, lege to have started an SN search in Capaccioli, M. & Schipani, P. 2011, The Messenger, eds. Hillebrandt, W., Leibundgut, B. (Heidelberg: 2011 and they all agree that the acronym 146, 2 Springer-Verlag)

32 The Messenger 151 – March 2013 Astronomical Science

Disentangling the Kinematics and Stellar Populations of Counter-rotating Stellar Discs in Galaxies

Lodovico Coccato1 Different scenarios have been proposed to simultaneously, allowing the different for- Lorenzo Morelli2, 3 explain the formation of these peculiar ob mation scenarios to be disentangled. Alessandro Pizzella2, 3 jects. The internal origin scenario (Evans & Enrico Maria Corsini2, 3 Collett, 1994) describes the dissolution of Lucio Maria Buson3 a triaxial potential or a bar. In this process, Results of the spectroscopic observations Elena Dalla Bontà2, 3 the stars, moving on box orbits, escape from the confining azimuthal potential well We started an observational campaign and move onto tube orbits. During this with the integral field unit (IFU) of the 1 ESO process, half of the box-orbit stars are VIMOS spectrograph at the VLT aimed at 2 Dipartimento di Fisica e Astronomia scattered onto clockwise-streaming tube determining the most efficient mecha- “G. Galilei”, Università degli Studi di orbits, the other half onto counterclockwise nisms in building large-scale counter- Padova, Italy ones. In this way, two identical counter- rotating stellar discs, like those observed 3 INAF–Osservatorio Astronomico di rotating stellar discs can be built. In the in NGC 4550. For this study, we devel- Padova, Italy gas accretion scenario, a disc galaxy oped a new spectroscopic decomposition acquires gas from extragalactic reservoirs technique that fits a galaxy spectrum and onto retrograde orbits (e.g., Pizzella et al., separates the contributions of two counter- Spectroscopic VIMOS/IFU observations 2004). If the amount of acquired gas is rotating stellar components (Coccato et are presented for three galaxies known sufficiently large, the new gas drives away al., 2011). At each position on the sky, the to host two stellar counter-rotating discs the pre-existing gas and it settles onto code builds two synthetic templates (one of comparable sizes. For the first time a counter-rotating disc. New stars are then for each stellar component) as a linear both the kinematics and stellar popu born from the acquired gas, forming the combination of spectra from an input stellation properties of the two counter- counter-rotating stellar disc. In the binary lar library, and convolves them with two rotating discs in the observed galaxies merger scenario (e.g., Crocker et al., 2009), Gaussian line-of-sight velocity distribu- were separated and measured. The two disc galaxies with opposite spin directions with different kinematics. Gaussian secondary, less massive, stellar compo- tions collide and form two coplanar coun- functions are also added to the convolved nent rotates in the same direction as the ter-rotating stellar discs, depending on the synthetic templates to account for ionised ionised gas and is on average younger geometry of the encounter. gas emission lines (Hγ, Hβ, [O iii] and [N i]). and less metal-rich than the main galaxy disc. These results support the scenario These different formation mechanisms are The spectroscopic decomposition code of gas accretion followed by star for expected to leave differing signatures in returns the spectra of two best-fit syn- mation as the origin for large counter- the properties of the stellar populations of thetic stellar templates and ionised gas rotating stellar discs in galaxies, and set the counter-rotating component. In par- emission (Figure 1), along with the best- an upper limit of 44% to those formed ticular, age is a key element in differentiat- fitting parameters of luminosity fraction, by binary galaxy mergers. ing among these scenarios. The internal velocity and velocity dispersion. The line origin predicts the same mass, luminosity, strengths of the Lick indices of the two chemical composition and age for both counter-rotating components are measu Counter-rotating galaxies counter-rotating stellar components. Gas red on the two best-fit synthetic templates. acquisition followed by star formation We then compare the indices Hβ, Mgb, Counter-rotating galaxies are those that predicts younger ages for the counter- Fe5270, and Fe5335 to the predictions of host two components that rotate in oppo- rotating stellar component in all cases, and stellar population models to infer the stel- site directions to each other. These pecu- it allows for different metallicity and lar age, metallicity ([Z/H]), and abundance liar objects have been observed in all mor- α-enhancement between the two discs. ratio of α-elements ([α/Fe]) of the two phological types, from ellipticals to spirals. Direct acquisition of stars through mergers counter-rotating discs. We also computed They are classed by the nature (stars vs. also allows for different metallicity and the mass-to-light ratios and the mass frac- stars, stars vs. gas, gas vs. gas) and size α-enhancement, but the younger compo- tion of the two counter-rotating compo- (counter-rotating cores, rings, discs) of nent will be determined by the difference nents from the luminosity fraction and the the counter-rotating components (see in age between the host galaxy and inferred stellar population parameters. Bertola & Corsini [1999] for a review). In the merged system. Roughly, one would The estimated mass is used to determine this work, we investigate the peculiar class expect younger counter-rotating stars in which component is the main (i.e., the of counter-rotating galaxies with two coun- ~ 50% of the cases. most massive) and which is the secondary ter-rotating stellar discs of comparable (i.e., the least massive). size. The prototype of this class of objects A proper spectroscopic decomposition is the famous E7/S0 galaxy NGC 4550, that separates the relative contribution of We started this project (programme IDs: whose counter-rotating nature was first the two counter-rotating stellar compo- 383.B-0632 and 087.B-0853A) by observ- discovered by Rubin et al. (1992). To date, nents to the observed galaxy spectrum is ing with VIMOS/IFU three galaxies that there are only a few known counter-rotating therefore needed. In this way, the kine were known to host counter-rotating stel- galaxies similar to NGC 4550, but the matics and the stellar populations of both lar discs of comparable size: NGC 3593 census will increase as a result of the new the stellar components can be measured (Bertola et al., 1996), NGC 4550 (Rubin et two-dimensional spectroscopic surveys. al., 1992) and NGC 5719 (Vergani et al.,

The Messenger 151 – March 2013 33 Astronomical Science Coccato L. et al., Counter-rotating Stellar Discs in Galaxies

Figure 1. Fit of the galaxy spec- Table 1. Luminosity-weighted values for the stellar '` ,F( %D( trum (black) in a spatial bin. The population parameters of the stellar discs. best-fitting model (green) is the sum of the spectra of the ionised gas component (magenta) and Age [Gyr] [Z/H] [α/Fe] TW the two stellar components (blue NGC 3593 Ck and red). The differences in the Main: 3.6 ± 0.6 −0.04 ± 0.03 0.09 ± 0.02 position of absorption line features Secondary: 2.0 ± 0.5 −0.15 ± 0.07 0.18 ± 0.03 and in the Hβ equivalent widths NGC 4550 -NQL@KHRD between the two stellar compo- Main: 6.9 ± 0.6 −0.01 ± 0.03 0.20 ± 0.02 nents (indicating different kinemat- Secondary: 6.5 ± 0.5 −0.13 ± 0.04 0.28 ± 0.02 ics and stellar population content) NGC 5719 are clearly evident. Main: 4.0 ± 0.9 0.08 ± 0.02 0.10 ± 0.02 Secondary: 1.3 ± 0.2 0.3 ± 0.02 0.14 ± 0.02 6@UDKDMFSGÄ

2007). The combination of the collecting are younger, more metal-poor, and have the kinematics and the Lick indices of power of an 8-metre-class telescope, the higher abundances of α-elements than the fitted components. The measured large wavelength coverage (4150–6200 Å) the main stellar discs. kine matics are used to construct the two- and the high spectral resolution (full width dimensional velocity fields, where the half maximum [FWHM] of 2.0 Å) with the Table 1 summarises the mean properties structure of the adopted spatial binning is HR-blue grism makes VIMOS on the VLT of the two counter-rotating stellar popula- still visible, and the counter-rotation the best-suited integral field unit for this tions, and Figures 2, 3 and 4 illustrate our between the two stellar components is kind of study. results. In these figures, the extension of remarkable (lower panels). The Lick indi- the VIMOS/IFU field of view is plotted over ces are shown in the diagnostic plots In all the sample galaxies, we confirm the the galaxy image (upper-left panels). The (upper right panels) with the predictions of presence of two stellar discs of compara- collected spectra are then spatially binned single stellar population models (Thomas ble size, and one ionised gas component. over the field of view with the Voronoi et al., 2011). We use Hβ and the combined The secondary stellar component and the binning technique to increase the signal- [MgFe]: = √(Mgb · [0.82 · Fe5270 + 0.28 · ionised gas component counter-rotate to-noise ratio (see Coccato et al. [2013] for Fe5335]) index as indicator of stellar age with respect to the main stellar disc. More- further details). The spectral decomposi- and metallicity. We also take into account over, in all the observed galaxies, these tion technique is then applied on the the variation in the abundance of counter-rotating secondary components spectrum of each spatial bin to measure α-elements and metallicity by measuring

-&" Figure 2. Results of the FD&XQ :_%D< spectroscopic decom- FD&XQ %D<l :_ position of NGC 3593. %D< FD &XQ :_ The top left panel shows the galaxy image with FD&XQ B %D< the location of the _ Ä : RD

Ä VIMOS observed field of

QB :9'< ` FD&XQ D view. The bottom panels ' "@ % :9'< :9'<l FD&XQ show the two-dimen- #$

6 l FD&XQ :9'< sional kinematics of the :9'<l :9'< :9'<l :9'< FD&XQ main, secondary and :9'< l ionised gas compo- JOB :9'<l nents, respectively. The top-right panels show l ll the measured equivalent 61 @QBRDB ,F%DÄ ,FAÄ width of the Lick indices; ,@HMBNLONMDMS 2DBNMC@QXBNLONMDMS (NMHRDCF@R grids with the predictions -&" - -&" -&" from single stellar population models are also shown. The crosses on the top-right side of the panels show the mean B B B error bars on the meas- RD RD RD

QB QB QB ured indices. Each spatial bin returns two sets 8@ 8@ 8@ of Lick indices, one for l l l each stellar component: red symbols represent OB the main stellar compo- l l l nent, whereas blue sym- l l l l l l bols represent the sec- 7@QBRDB 7@QBRDB 7@QBRDB ondary counter-rotating l l l l l l component. 5JLR 5JLR 5JLR

34 The Messenger 151 – March 2013 -&" Figure 3. As Figure 2, _%D< FD&XQ but for NGC 4550. FD&XQ

%D<l FD &XQ _ %D< FD&XQ _ B Ä RD Ä

%D< QB ` FD&XQ _ ' :9'< %D "@ :9'<l FD&XQ :9'< #$ 6 FD&XQ l :9'<l :9'< :9'<l :9'< FD&XQ :9'< l :9'<l JOB

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` FD&XQ ' "@ %D :9'< :9'<l FD&XQ #$ :9'< 6 l FD&XQ :9'<l :9'< :9'<l :9'< FD&XQ :9'< l JOB :9'<l

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The Messenger 151 – March 2013 35 Astronomical Science Coccato L. et al., Counter-rotating Stellar Discs in Galaxies

the magnesium Mgb index and the mean &@K@WHDRVHSGK@QFDlRB@KDBNTMSDQlQNS@SHMFRSDKK@QCHRBR Figure 5. Schematic iron index = (Fe5270 + Fe5335)/2. representation of the probability PE of observ- (. - ing the secondary stellar 3 NGC 3593. An isolated, highly inclined, disc younger than the

S0/a spiral at a distance of 7 Mpc. It is .1, main galaxy disc, as a characterised by a patchy spiral dust pat- l,EQ@BSHNMNEBNTMSDQlQNS@SHMF ,EQ@BSHNMNEBNTMSDQlQNS@SHMF function of the fraction F@K@WHDROQNCTBDCAXF@R@BBQDSHNM F@K@WHDROQNCTBDCAXAHM@QXLDQFDQR M of galaxies formed tern in the centre. The two counter-rotat- through the binary gal- ing stellar discs have different scale axy merger scenario. lengths, but the same intrinsic flattening.

The secondary component dominates the 2% RDBNMC@QX RDBNMC@QX OQHL@QX BNLONMDMSXNTMFDQ BNLONMDMSXNTMFDQ BNLONMDMSXNTMFDQ innermost 500 pc. The ages of the two (.- %Q@BSHNMl, %Q@BSHNM, %Q@BSHNM, components date the accretion event to 3 between 2.0 and 3.6 Gyr ago, i.e., 1.6 ± /QNA@AHKHSX/$NEjMCHMF@BNTMSDQlQNS@SHMFF@K@WXVHSG 0.8 Gyr after the formation of the main RDBNMC@QXBNLONMDMSXNTMFDQSG@MSGDL@HMBNLONMDMS .!2$15 / ,l, ,l, stellar disc (Coccato et al., 2013). $

NGC 4550. An E7/S0 galaxy in the Virgo

Cluster, at a distance of 16 Mpc, and it is The most efficient mechanism to build mising ΠE (M). In our case N = T = 3, often indicated as the prototype of galax- counter-rotating stellar discs therefore MMAX < 44% at 1σ confidence ies with counter-rotating stellar discs. It level. has an elliptical galaxy nearby, NGC 4551, Our results favour the external origin of to the northeast of NGC 4550 at a pro- the counter-rotating components in all Thus, it is fundamental to measure the dif- jected distance of 14 kpc. An interaction in the three observed galaxies, and discard ference in ages of the counter-rotating the past between these two systems the internal origin scenario. As stated components in a larger sample of counter- could have produced the counter-rotating above, in the gas-accretion scenario the rotating galaxies to identify the most effi- stellar disc in NGC 4550, although no stellar component associated with the cient mechanism and derive more precise photometric signatures of the interaction, ionised gas is predicted to always be constraints. Large spectroscopic surveys such as tidal tails or gas streams, have younger than the main stellar component. like MaNGA will help to identify other been detected. The two counter-rotating In binary galaxy mergers instead, one potential candidates by recognising the stellar discs in NGC 4550 have the same would expect that the younger stellar kinematic signatures of stellar counter- scale lengths, but slightly different ellip component is associated with the ionised rotating discs, such as the two symmetric ticity (εmain = 0.6, εsecond = 0.5) meaning gas only in 50% of the cases. Although peaks in the velocity dispersion map. that they have different scale heights. The we always observe the secondary compo- The MaNGA survey is one of the Next measured ages date the accretion event nent to be younger than the main galaxy Generation Sloan Digital Sky Surveys, and ~ 7 Gyr ago, i.e. less than 1 Gyr after the disc, thus favouring the gas accretion it will collect IFU spectroscopic data for formation of the main stellar disc (Coccato scenario, we cannot rule out the binary ~ 10 000 galaxies in the nearby Universe et al., 2013). galaxy merger scenario. within six years. Moreover, the next generation integral field unit MUSE at the VLT NGC 5719. An Sab galaxy at a distance On the other hand, we can infer an upper will represent a significant step forward for of 23 Mpc, and a member of a rich group. limit to the fraction of galaxies with two these studies, because of the better It is currently interacting with the Sbc counter-rotating stellar discs that were spectral resolution, wavelength coverage galaxy NGC 5713, which is to the west of formed by binary mergers by statistical and field of view with respect to VIMOS. NGC 5719 at a projected distance of arguments. We define M as the fraction 77 kpc. The interaction between the two of galaxies hosting two counter-rotating systems is traced by a bridge of neutral stellar discs of comparable sizes that were References hydrogen (Vergani et al., 2007), which fuels generated by a binary major merger (thus, Bertola, F. & Corsini, E. M. 1999, IAU Symposium, the secondary counter-rotating stellar (1 – M) is the fraction produced by gas 1 8 6 , Galaxy Interactions at Low and High component in NGC 5719. The two s tellar accretion), and E as the event of finding Redshift, eds. Barnes, J. E. & Sanders, D. B. components in NGC 5719 have similar the stellar component co-rotating with the ( Dordrecht: Kluwer), 149 luminosity, but the secondary is less mas- gas to be the youngest. The probability Bertola, F. et al. 1996, ApJ, 458, L67 Coccato, L. et al. 2011, MNRAS, 412, L113 sive because of its younger age. Moreover, PE to observe E is: PE = 1 – M/2 (see Fig- Coccato, L. et al. 2013, A&A, 549, 3 the youngest ages are observed in the ure 5). The probability ΠE (M) of observing Crocker, A. F. et al. 2009, MNRAS, 393, 1255 secondary component at ~ 700 pc from E in exactly N galaxies out of a sample Evans, N. W. & Collett, J. L. 1994, ApJ, 420, L67 the centre, where the H emission lines of T counter-rotating galaxies is given by Pizzella, A. et al. 2004, A&A, 424, 447 β Rubin, V. C., Graham, J. A. & Kenney, J. D. P. 1992, are more intense (Coccato et al., 2011). the first term of the binomial distribution. ApJ, 394, L9 The ages of the two components date the It is therefore possible to compute the Thomas, D., Maraston, C. & Johansson, J. 2011, accretion event between 1.3 and 4.0 Gyr most probable value for the fraction of MNRAS, 412, 2183 ago, i.e. 2.7 ± 0.9 Gyr after the formation of counter-rotating galaxies produced Vergani, D. et al. 2007, A&A, 463, 883 the main stellar disc (Coccato et al., 2011). by binary mergers, MMAX, simply by maxi

36 The Messenger 151 – March 2013 Astronomical Science

Angular Momentum of Galaxies in the Densest Environments: A FLAMES/GIRAFFE IFS Study of the Massive Cluster Abell 1689 at z = 0.18

Francesco D’Eugenio1 of these empirical laws — alongside their bined with the collecting power of the Ryan C. W. Houghton1 very small scatter — imposes strong ESO Very Large Telescope (VLT), are the Roger L. Davies1 constraints on the structure and evolution ideal tools for this task. Elena Dalla Bontà2, 3 of ETGs (Bower et al., 1992). This makes them ideal testing grounds for any galaxy formation theory. Their study, important FLAMES/GIRAFFE observations of 1 Sub-department of Astrophysics, in its own right, is also fundamental Abell 1689 Department of Physics, University of for our understanding of the process of Oxford, United Kingdom structure formation in the Universe. Abell 1689, a massive galaxy cluster at 2 Dipartimento di Fisica e Astronomia redshift z = 0.183, has regular, concen- “G. Galilei”, Università degli Studi di The advent of integral field spectroscopy tric X-ray contours suggesting that it Padova, Italy (IFS) started a revolution in the study of is relaxed. Its X-ray luminosity outshines 3 INAF–Osservatorio Astronomico di ETGs. The SAURON survey discovered Coma by a factor of three, and Virgo Padova, Italy the existence of two kinematically distinct by over an order of magnitude. Its comov- classes of ETGs, slow and fast rotators ing distance is 740 Mpc, giving a scale (SRs and FRs, see Emsellem et al. [2007]) of 1 arcsecond per 3.0 kpc. Alongside its Early-type galaxies (ETGs) exhibit kine- and Cappellari et al. (2007). The former physical properties, Abell 1689 was an matically distinct slow and fast rotator have little or no rotation, exhibit kinemati- ideal target for FLAMES because the (SR, FR) morphologies. The former cally decoupled cores and misalignment spatial resolution of the GIRAFFE-deploy- are much less common (10% of ETGs), between kinematics and photometry. The able integral field units (IFUs) samples up but their incidence is higher in the core latter are flattened systems, compatible to one effective radius (Re) for most gal- of the Virgo Cluster (25%). Here we pre- with rotational symmetry and a disc-type axies. Finally, a wealth of archival data, sent FLAMES/GIRAFFE integral field origin. The new division c rucially crosses including imaging from the Hubble Space spectroscopy of 30 galaxies in the mas- the boundary between Es and S0s, in Telescope (HST) Advanced Camera for sive cluster Abell 1689 at z = 0.183. that FRs populate both morphological Surveys (ACS), is available and vital to a Abell 1689 has a density 30 times classes. ATLAS3D (the volume-limited fol- study of this nature. higher than that of Virgo, making it the low-up survey to S AURON; Cappellari ideal place to test the effects of envi- et al., 2011a; Emsellem et al., 2011), F625W-band imaging from the HST ACS, ronment, such as local density and established that 66% of morphological combined with g:- and r:-band GEMINI cluster properties. We find 4.5 ± 1.0 ellipticals are FRs, and thus share the imaging were used for the photometry

SRs (or an average ETG fraction, ƒSR, of same internal structure as S0s. This is (Houghton et al., 2012). The spectroscopic 0.15 ± 0.03) in Abell 1689, identical to evidence for a new classification para- data (spectral resolution, R = 11 800, the value for field/groups in ATLAS3D. digm, based on kinematics rather than spectral range 573 nm < λ < 652 nm Within Abell 1689 ƒSR increases towards morphology (Cappellari et al., 2011b). [486 nm < λ < 552 nm rest frame]) covers the centre, exceeding the value found in standard V-band absorption features. the core of Virgo. This work is the high- The ATLAS3D team presented the kine- GIRAFFE provides 15 independent mini est redshift study of its kind. matic morphology–density (kT–Σ) relation, IFUs, deployable anywhere on the focal analogous to the morphology–density plane; each IFU is positioned by a mag- relation (Dressler, 1980). It links the frac- netic button and contains an array of

Kinematical classification of ETGs tion of SRs in the ETG population (ƒSR) 20 square microlenses. They are arranged with the local number density of galaxies: in four rows of six (with four “dead” cor-

ETGs comprise morphologically distinct they found that ƒSR is independent of ners) for a total field of view of 3 by 2 arc- elliptical (E) and lenticular (S0) galaxies. the environment density over five orders seconds. Each lenslet is then connected Despite their differences, Es and S0s of magnitude from field to group environ- to the spectrometer with a dedicated opti- have lots in common. They are both char- ments. But they noticed a sharp increase cal fibre bundle. Alongside the 15 IFUs, acterised by old stellar populations, which in ƒSR in the inner core of the Virgo Clus- the instrument also provides 15 fully de has earned them the attribute “early- ter, the highest density probed by the ployable sky fibres. type”. The average ETG has little or no ATLAS3D survey. Virgo is an unrelaxed, cold gas, which is reflected in the star low-density cluster, but what would be Since the magnetic buttons are larger formation rate. Its light profile is smooth measured in the denser environments (10 arcseconds) than the IFU field of view, and its shape fairly regular. One of the beyond the local Universe? Addressing they cannot be deployed closer than a most puzzling facts about these galaxies this question gives further insight on minimum distance of 11 arcseconds. is how, with masses and luminosities that the kT–Σ relation, and on the processes GIRAFFE permits the observer to target span several orders of magnitude, they that drive galaxy formation and evolution. 15 objects simultaneously and we chose obey a number of tight scaling relations. to target 30 galaxies as a compromise These include the colour–magnitude Since rich, relaxed clusters are rare, they between sample statistics and integration relation, the colour–σ and Mg–σ relations can only be found at higher redshifts. time. In order to gain the maximum pos- (where σ is the velocity dispersion) and the The multiplexing capabilities of FLAMES/ sible signal-to-noise ratio, we initially fundamental plane. The mere existence GIRAFFE (Pasquini et al., 2002), com- selected the 30 ETGs with the highest

The Messenger 151 – March 2013 37 Astronomical Science D’Eugenio F. et al., Angular Momentum of Galaxies in the Densest Environments

01 02 03 Figure 1. Kinematic –150/150 0/225 –100/100 0/125–150/1500/225 maps of the Abell 1689 sample. For each of the 30 galaxies in the sample we present a set of four images. The first 04 05 06 –100/100 0/125 –100/100 0/300–100/1000/325 one shows FLAMES/ GIRAFFE IFU footprints superimposed on HST imaging (Gemini imaging for target 20). The second plot shows the 07 08 09 –100/100 0/150 –100/100 0/225–100/1000/150 reconstructed image from VLT integral field spectroscopy, where each square is a spaxel and corresponds to a 10 11 12 lenslet of the IFU. Also –100/100 0/225 –100/100 0/150–100/1000/350 shown is an isophote at

either Re, or the closest integer fraction that fits into the IFU footprint. The four black corners 13 14 15 –100/100 0/200 –175/175 0/325–100/1000/200 correspond to unavaila- ble “dead” spaxels, while other black spaxels (seen in 11, 15 and 30) correspond to bro- ken or unused fibres. 16 17 18 –100/100 0/175 –250/250 0/325–125/1250/200 Velocity and velocity dispersion maps are depicted in the third and fourth plots. The black compass arrows show 19 20 21 north and east direc- –100/100 0/275 –100/100 0/150–100/1000/150 tions. Colour-bar limits are given in km/s.

22 23 24 –200/200 0/250 –100/100 0/200–100/1000/200

25 26 27 –200/200 0/225 –100/100 0/275–100/1000/250

28 29 30 –175/175 0/175 –150/150 0/200–100/1000/200

surface brightness within a 3-arcsecond was exposed five times for two hours, for tions of the Virgo Cluster (for which the radius. This sample was then subject a total of ten hours per galaxy. The ob SR population is known from ATLAS3D) to two practical constraints. We needed servations were carried out in visitor using the luminosity function of our sam- all of our targets to have high-resolution mode, which proved to be both efficient ple. This showed that we could recover

HST imaging, which limited our choice to and accurate in terms of object acquisi- the true value of ƒSR for Abell 1689. candidates in the innermost regions of tion. Excellent seeing of 0.60 arcseconds Although we did not do a colour selec- the cluster. The 11-arcsecond proximity reduced the correlation between neigh- tion, our sample falls entirely on the Red constraint ruled out some targets in the bouring spaxels. Sequence (RS). However, the number most crowded regions, forcing us to re- of galaxies that do not fall on the RS in select from a reserve list. This left us with Our sample is biased towards bright Abell 1689 is extremely low, and we 29 galaxies inside the HST field of view ob jects, which in turn could bias us to found the bias to be minimal. and one outside (galaxy 20). Each plate detect more SRs. We simulated observa-

38 The Messenger 151 – March 2013

(%4 (%4 1 1 h h

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Figure 2. λR(IFU) vs. εe for the simulated observations in the Virgo core (Cappellari et al., 2011b). Figure 3. λR(IFU) vs. εe for all target galaxies in Abell of the SAURON sample of galaxies. The green lines However, contamination from face-on 1689. The green line separates FRs (blue dots separate SRs (below) from FRs. Red and blue circles above) from SRs (red dots below). The magenta and denote SRs and FRs respectively, according to the discs, which may appear as SRs, can dashed lines represent the view of an axisymmetric original SAURON classification (Emsellem et al., bias the estimate. galaxy, edge-on and at various inclinations. Details 2007). Due to the different observing setup, some about these models are given in Cappellari et al. galaxies have been misclassified: these are the red Five more objects, despite exhibiting (2007) and Emsellem et al. (2011). dots above the green line and the blue dots below. large-scale rotation, have misaligned kinematic and photometric axes, a fea- To reduce the FLAMES/GIRAFFE data we ture more common in SRs than in FRs introduces additional differences used the official ESO pipeline1, following ( Krajnovíc et al., 2011): these are galaxies between our setup and that of ATLAS3D, the guidelines ESO offers2. Stellar kine- 1, 3, 5, 9, 17 and 25 (Figure 1). Galaxies 3 but we used existing SAURON data to matics were extracted using pPXF3; we and 17 have very high ellipticities, and determine how our observations and def- used a line-of-sight velocity dispersion are thus unlikely to be SRs, which have inition compare to those of ATLAS3D. (LOSVD) expressed by a Gaussian func- ellipticity ε < 0.4. Galaxy 5 has high We made models of the SAURON galax- tion, obtaining just the velocity V and velocity dispersion, and also contains ies using kinemetry5 and, after projecting velocity dispersion σ. The stellar template an inner disc (R = 1.5 kpc) in the HST at redshift z = 0.183 and convolving with library of choice was the high-resolution imaging. the seeing, we sampled them using the version (R = 40 000) of the ELODIE tem- FLAMES/GIRAFFE setup. The resulting plate library4. simulated data, after adding noise, have

λR measurements and kinematic classifi- been used to measure λR, which we then cation compared with the original SAURON Slow and fast rotators at z = 0.18 values to estimate both bias and system- Emsellem et al. (2007) introduced the atic error.

Figure 1 shows the resulting kinematic estimator λR to measure the projected maps. Although the spatial resolution is specific angular momentum of galaxies; We corrected λR(IFU) according to the low (compared to SAURON) rotation can and Emsellem et al. (2011) further show bias measured and included the system- be clearly seen in some galaxies, and not how the combination of λR and ε con atic error in quadrature with the random in others. veniently captures the kinematic bound- error. This correction takes into account ary between SRs and FRs. They define both the different apertures between

Since our spatial resolution is coarse, we λR(Re) as the value of λR computed inside λR(IFU) and λR(Re) and the different spatial cannot detect kinematically decoupled Re, and use it in their λR(Re) vs. ε diagram. resolutions between λR(IFU) and εe. In cores (KDCs) and double σ peaks (2σ) as Figure 2 we plot simulated v alues of in Krajnovíc et al. (2011). If we try to In our study the galaxies are not sampled λR(IFU) against published values of εe detect SRs from the velocity maps by eye evenly, because Re varies while the size (Emsellem et al., 2007). Despite the afore- (as done by the SAURON and ATLAS3D of the IFUs is fixed. We cannot follow the mentioned differences, there is little teams) we identify at most six: galaxies 4, ATLAS3D prescription precisely and there- (< 10%) misclassification in our diagram,

8, 12, 20, 26 and 27 (see Figure 1). The fore introduced λR(IFU); defined as the especially at high values of Re. Given overall value of ƒSR in the sample would value of λR computed using all the availa- the known uncertainties, we can calcu- then be 0.20, in line with what was found ble spaxels in the IFU field of view. This late the probability distribution for the

The Messenger 151 – March 2013 39 Astronomical Science D’Eugenio F. et al., Angular Momentum of Galaxies in the Densest Environments

measured number of SRs in the SAURON Figure 4. Fraction of slow rotators ƒSR over the ETG population, as a function survey (galaxies below the green line in of the environment density. The green Figure 2 defined by 0.31√ε and the green circles and line are from the ATLAS3D line in Figure 2, Emsellem et al. [2011]). survey (Cappellari et al., 2011b), red We adopt a Monte Carlo approach (for symbols are for Abell 1689. The num- each galaxy we assumed Gaussian bers at the top give the total number of galaxies in each bin. The uncertainty errors in λR). The resulting probability dis- in the SR classification is reflected 21 tribution is Gaussian-like and we find c in the error bars. The green square is 12.3 ± 1.7 slow rotators, where the true the value of ƒSR that we measure, value is 12. resampling Virgo using our sample 5HQFNBNQD luminosity function. The error bars are smaller than the point size. The aver- When we correct the values for our Abell age fraction for Abell 1689 is shown by 1689 data in the same way (Figure 3), the red square. we can similarly calculate the probability distribution for the number of SRs in l KNF- ,OBl Abell 1689. This analysis finds 4.5 ± 1.0 slow rotators, corresponding to ƒSR = 3D 0.15 ± 0.03. starts exactly where ATLAS finished. age particle mass. Hence the higher ƒSR Abell 1689 shows a sharp increase in ƒSR in the core of clusters is consistent with Emsellem et al. (2007) warn about using with projected density, from ƒSR = 0.01 in the effects of dynamical friction. only λR to assign a galaxy to either the least dense environment to ƒSR = 0.58 the slow or fast rotator class. The dis- in the innermost regions. The densest On account of the importance of the crepancy between the classification “by bin in Abell 1689 has a higher fraction of SR/FR division in understanding galaxy eye” and the classification we adopted SRs than the core of Virgo (Figure 4). formation/evolution, it is crucial to expand here underscores that warning. However, The intermediate bin has a value of ƒSR this study, in particular by increasing the when studying galaxies beyond the local compatible with both the field/group number of observed clusters, to quantify

Universe, a detailed analysis such as that envi ronments and the overall Virgo clus- the scatter in ƒSR and the radial variation carried out by the ATLAS3D team is not ter value, but is less than the Virgo core. within different clusters. Sampling clus- feasible. We are thus forced to rely on a ƒSR in the least dense bin is lower than ters with different densities and dynami- statistical approach. the ATLAS3D field and group values. cal states would give us great insight on the topic. Observations of the Abell 1650 Considering the whole Abell 1689 sam- cluster, with an intermediate mass, lying

Slow rotators and environment density ple, we find an average value of log10 Σ3 = between that of Virgo and Abell 1689, are 2.77 and a SR fraction of 0.15 ± 0.03 (red already scheduled at the VLT. Interesting For each galaxy in the sample we esti- square in Figure 4), which is the same times are ahead! mate the local environment density as the overall SR fraction in the Virgo following Cappellari et al. (2011b). We cluster, when sampled in the same way References defineΣ 3 as the number density of galax- (green square). Furthermore, both values ies inside the minimum circular area, are similar to the field and group samples Bower, G., Lucey, J. R. & Ellis, R. S. 1992, MNRAS, 3D centred on the target galaxy, and encom- in ATLAS , suggesting little to no dif 254, 613 passing three other galaxies (down to ference in ƒSR when it is averaged over an Cappellari, M. et al. 2007, MNRAS, 379, 418 a magnitude limit). Interlopers were dealt entire cluster population. Cappellari, M. et al. 2011a, MNRAS, 413, 813 with by subtracting everywhere a con- Cappellari, M. et al. 2011b, MNRAS, 416, 1680 Dressler, A. 1980, ApJ, 236, 351 stant mean value of Σ3 = 0.49 galaxies Abell 1689 has a higher average density Emsellem, E. et al. 2007, MNRAS, 379, 401 per square arcminute. In Figure 4 we than Virgo, but the same average slow Emsellem, E. et al. 2011, MNRAS, 414, 818 Houghton, R. C. W. et al. 2012, MNRAS, 423, 256 show ƒSR versus log10 Σ3 for Abell 1689 rotator fraction ƒSR. Inside the cluster, ƒSR (red), compared to the results of the rises with projected density. In the least Krajnovíc, D. et al. 2011, MNRAS, 414, 2923 3D Pasquini, L. et al. 2002, The Messenger, 110, 1 ATLAS survey (green; Cappellari et al., dense region, ƒSR is significantly smaller 2011b). The densest environment in than the ATLAS3D field/group value. Given ATLAS 3D (i.e., the core of the Virgo Clus- the low number of galaxies per bin, we Links ter) has ƒ = 0.25, double that typi- cannot rigorously claim that this is repre- SR 1 ESO Giraffe Pipeline: http://www.eso.org/sci/soft- cally found in less dense environments sentative. However, a similar “depletion” ware/pipelines/giraffe/giraf-pipe-recipes.html 2 (ƒSR ≈ 0.12). is observed in the outskirts of the Virgo Guidelines for Giraffe Pipeline: ftp://ftp.eso.org/ cluster (Cappellari et al., 2011b). SRs are pub/dfs/pipelines/giraffe/giraf-manual-2.8.7.pdf 3 In this study we probed e nvironments uniformly distributed across a range of pPXF: http://www-astro.physics.ox.ac.uk/~mxc/idl/ 4 Elodie template library: www.obs-u-bordeaux1.fr/ with values of log10 Σ3 between 2.06 environments; we know that they are on m2a/soubiran/elodie_library.html and 3.75: the minimum is comparable to average more massive than FRs, and 5 Kinemetry: www.davor.krajnovic.org/idl the core of Virgo, and the maximum is that dynamical friction is more efficient in 1.7 dex higher. In this respect our work objects with mass higher than the aver-

40 The Messenger 151 – March 2013 Astronomical Science

VIPERS: An Unprecedented View of Galaxies and Large- scale Structure Halfway Back in the Life of the Universe

Luigi Guzzo1 performed with ESO telescopes. In this in the measured galaxy correlations. The and the VIPERS Team* article we describe the survey construc- observed anisotropy is proportional to tion, together with early results based the growth rate of cosmic structure ƒ(z), on a first sample of 55 000 galaxies. which is a trademark of the gravity the- 1 INAF–Osservatorio di Brera, Milano, Italy ory: if GR holds, we expect to measure a 0.55 growth rate ƒ(z) = [Ωm(z)] (Peebles, There is no doubt that one of the major 1980). RSD are now recognised as one of The VIMOS Public Extragalactic Red- achievements of observational cosmology the primary ways to make this test (Guzzo shift Survey (VIPERS) is an ongoing in the 20th century has been the detailed et al., 2008). Directly probing the ampli- Large Programme to map in detail the reconstruction of the large-scale structure tude and anisotropy of clustering, redshift large-scale distribution of galaxies at of the Universe around us. Starting in the surveys promise to play a major role also 0.5 < z <1.2. With a combination of vol- 1970s these studies developed into what in 21st-century cosmology, at least as ume and sampling density that is nowadays is the industry of redshift sur- important as they did in the past one, as unique for these redshifts, it focuses on veys, beautifully exemplified by the ever- several planned experiments, including the measuring galaxy clustering and related growing Sloan Digital Sky Survey project forthcoming ESA Euclid mission (Laureijs cosmological quantities as part of the (SDSS, e.g., Eisenstein et al., 2011). et al., 2011), testify. grand challenge of understanding the origin of cosmic acceleration. Moreover, Maps of the large-scale galaxy distribu- However, the yield of a redshift survey is VIPERS has been designed to guaran- tion have shown not only that the topol- much more than this. By building statis tee a broader legacy, allowing detailed ogy of large-scale structure is quite dif tically complete samples of galaxies with investigations of the properties and ferent from how it was imagined at the measured luminosity, spectral properties evolutionary trends of z ~ 1 galaxies. time of Edwin Hubble and Fritz Zwicky, and often colours and stellar masses, The survey strategy exploits the spe- but have also been crucial to quantita- they are a key probe of galaxy formation cific advantages of VIMOS, aiming at a tively supporting the current, successful and evolution and of the relationship final sample of nearly 100 000 galaxy model of cosmology. The inhomogeneity between the baryonic component that redshifts to iAB = 22.5 mag, which repre- that we can measure in the galaxy dis we observe and the hosting dark-matter sents the largest redshift survey ever tribution on different scales is one of the halos. A survey like the SDSS, for exam- most important relics of the initial con ple, based on one million redshifts, was ditions that shaped our Universe. The able to measure to exquisite precision * The VIPERS Team: observed shape of the power spectrum global galaxy population trends involving L. Guzzo1 (P.I.), U. Abbas2, C. Adami3, S. Arnouts3, 4, P(k) of d ensity fluctuations (or its Fourier properties such as luminosities, stellar J. Bel5, M. Bolzonella6, D. Bottini7, E. Branchini8, transform, the correlation function (r)), masses, colours and structural parame- 9 6, 10 11 6 ξ A. Burden , A. Cappi , J. Coupon , O. Cucciati , indicates that we live in a Universe in ters (e.g., Kauffmann et al., 2003). I. Davidzon12, 6, S. de la Torre13, G. De Lucia14, C. Di Porto6, P. Franzetti7, A. Fritz7, M. Fumana7, which only ~ 25% of the mass–energy B. Garilli7, B. R. Granett1, L. Guennou3, O. Ilbert3, density is provided by (mostly dark) mat- In more recent years, deeper redshift A. Iovino1, J. Krywult15, V. Le Brun3, O. Le Fevre3, ter. Combined with other observations, it surveys over areas of 1–2 square degrees 7 16 17, 1 D. Maccagni , K. Malek , A. Marchetti , also implies that a ubiquitous repulsive have focused on exploring how this C. Marinoni5, F. Marulli12, H. J. McCracken18, Y. Mellier18, L. Moscardini12, R. C. Nichol9, L. Paioro7, “dark energy” is required to provide the detailed picture emerged from the distant J. A. Peacock13, W. J. Percival9, S. Phleps19, remaining ~ 75% and make sense of the past. Most of these efforts saw the VLT M. Polletta7, A. Pollo20, 21, H. Schlagenhaufer19, overall picture. and the VIMOS spectrograph play a cen- 7 16 3 9 M. Scodeggio , A. Solarz , L. Tasca , R. Tojeiro , tral role, specifically in the case of the D. Vergani22, M. Wolk18, G. Zamorani6, A. Zanichelli23 The peculiar motions of galaxies, which VVDS (VIMOS–VLT Deep Survey; Le 1 INAF–Osservatorio di Brera, Milano, Italy; 2 INAF– reflect the overall growth of structure Fevre et al., 2005) and zCOSMOS (Lilly Osservatorio di Torino, Italy; 3 LAM, Marseille, driven by gravitational instability, also et al., 2009) surveys. The main goal of 4 France; Canada-France-Hawaii Telescope, Hawaii, produce measurable effects on these these projects was to trace galaxy evolu- USA; 5 CPT Universite de Provence, Marseille, France; 6 INAF–Osservatorio di Bologna, Italy; 7 clustering measurements. They provide a tion back to its earliest phases and/or INAF–IASF Milano, Italy; 8 Universitá Roma 3, Rome, way to check whether the “dark energy” understand its relationship with environ- Italy; 9 ICG, University of Portsmuth, United Kingdom; hypothesis is really correct, or rather that ment. Only the Wide extension of the 10 Université de Nice, Obs. de la Cote d’Azur, Nice, the observed acceleration is indicating VVDS (Garilli et al., 2008), encompassed France; 11 Inst. of Astron. and Astrophys., Academia Sinica, Taipei, Taiwan; 12 Dip. di Fisica e Astronomia, a more radical possibility, i.e., that the sufficient volume to attempt cosmologi- Universitá di Bologna, Italy; 13 Institute for Astronomy, theory of general relativity (GR), describ- cally meaningful computations (Guzzo et University of Edinburgh, United Kingdom; 14 INAF– ing the force of gravity, needs to be al., 2008), but with large error bars. At 15 Osservatorio di Trieste, Italy; Jan Kochanowski revised on large scales. the end of the past decade it therefore University, Kielce, Poland; 16 Dept. of Particle and Astrophys. Science, Nagoya Univ., Japan; became clear to us that a new step in 17 Universitá degli Studi di Milano, Italy; 18 IAP, Paris, Galaxy velocities affect the measured deep redshift surveys was needed, in the France; 19 MPE, Garching, Germany; 20 Astronomi- redshifts and produce what are known direction of building a sample at z ~ 1 cal Observ., J agiellonian University, Cracow, Poland; as redshift space distortions (RSD) in with volume and statistics comparable to 21 National Centre for Nuclear Research, Warsaw, Poland; 22 INAF–IASF Bologna, Italy; 23 INAF–IRA the maps of large-scale structure (Kaiser, those of the available surveys of the local Bologna, Italy 1987; Peacock et al., 2001) and, in turn, Universe.

The Messenger 151 – March 2013 41 Astronomical Science Guzzo L. et al., VIPERS

VIPERS Figure 1. Snapshots from the VIPERS project monitoring web page, giving the detailed status of each VIMOS VIPERS was conceived to fill this gap pointing that is part of the survey. The by exploiting the unique capabilities of two images shown here refer to the VIMOS. Started in Period 82, the sur- PDR-1 catalogue discussed in the vey aimed to measure redshifts for ~ 105 text, which contains data observed up to January 2012. These correspond to galaxies at 0.5 < z < 1.2, covering an the areas depicted in red. Other col- unprecedented volume. Its goals are to ours mark different phases of the data accurately and robustly measure galaxy acquisition/processing. The large clustering, the growth of structure and number of grey rectangles in W4 (bottom) represents VIMOS quadrants galaxy properties at an epoch when the for which the mask insertion failed. As Universe was about half its current age. can be seen, field W4 is nearly com- The galaxy target sample is based on the plete. excellent five-band photometric data of the Canada–France–Hawaii Telescope Legacy Survey Wide catalogue (CFHTLS– Wide1).

To achieve its goals, VIPERS covers ~ 24 square degrees with a mosaic of 288 VIMOS pointings, split over two areas in the W1 and W4 CFHTLS fields (192 and 96 pointings respectively). With a total exposure time of 45 minutes per VIMOS pointing, VIPERS will use a total of 372 hours of multi-object spectrograph (MOS) observations, plus 68.5 hours of pre-imaging. Its area and depth correspond to a volume of 5 × 107 h–3 Mpc3, VIMOS, a fully automated pipeline to analyses, the distribution of results and similar to that of the 2dF Galaxy Redshift process the observations from the raw draft papers, can be monitored and co Survey at z ~ 0 (Colless et al., 2001). frames to the final redshift measurement ordinated through related web pages. Such a combination of sampling and vol- was set up at INAF–IASF in Milan. In this Finally, validated redshifts and spectra ume is unique among redshift surveys scheme, human work is limited only to are fed into an SQL-based database at at z > 0.5. The target sample includes all the final verification and validation of the the completion of the validation phase, galaxies with iAB < 22.5 mag, limited to measurements, which is still necessary such that the real-time survey catalogue z > 0.5 through a robust ugri colour pre- to recover about 20% of the correct red- (visible only to the data handling group) is selection. The use of an aggressive short- shifts for the lowest quality data. constantly and automatically updated to slit strategy (Scodeggio et al., 2009), the very last redshift measured. Internal allows the survey to achieve a sampling Most importantly, the whole management releases can then be made by simply rate > 40%. The VIMOS low-resolution and book-keeping of the survey process creating a snapshot of the catalogue at a red grism (spectral resolution R = 210), was also organised within a web-based given moment, assuring full version con- yields a spectral coverage between 5500 environment, named EasyLife (Garilli et trol on the catalogues used for science and 9500 Å, for a typical redshift root al., 2012). This is a key feature of VIPERS, investigations (internally or publicly) at any mean square (rms) error of σz = 0.00047 which allows us to control in real time stage of the project. A dedicated Wiki- (1 + z) (directly estimated from double any past, present and future events con- page system provides the team with the measurements of 1215 galaxies). These cerning each of the 288 VIMOS pointings appropriate environment for science dis- and more details on the survey con that compose the VIPERS mosaic, such cussions and to share results. Public web struction and the properties of the sam- as pre-imaging, mask preparation, real- pages are also available, to provide up ple can be found in Guzzo et al. (2013). time atmospheric conditions during the dates about the general project progress2. MOS observations, quality of the spectra, names of the redshift reviewers, etc. Survey and data management This is achieved through a point-and-click The VIPERS PDR-1 catalogue graphical interface, whose appearance Handling a spectroscopic survey of this is shown in Figure 1. The two panels give After processing, reduction and valida- size requires the automation of most the real-time status of each VIMOS point- tion, the data observed up until January of the typical operations and that human ing in the two W1 and W4 VIPERS fields. 2012 yielded a catalogue of 55 358 intervention is reduced to the minimum redshifts, representing about 60% of necessary. Building on the experience Similarly, the complete work output of the the final expected sample. This cata- accumulated with previous surveys using team, from data validation to the science logue, corresponding to the red areas in

42 The Messenger 151 – March 2013 structure, when the Universe was only 02h30m 02h15m 02h00m GL GL between five and eight billion years old.

The following step is to quantify the observed structure as a function of scale. One of the main goals of VIPERS is the measurement of the amplitude and an isotropy of the galaxy two-point correlation function: a first estimate from the PDR-1 sample is shown in the two panels of Figure 4. Crucial for these measurements is an accurate knowledge of several ancillary pieces of information from the survey, such as the photometric and spectroscopic angular selection masks, the target sampling rate and the spectroscopic success rate. These allow us to assign a weight to every observed galaxy

in the survey to correct for the overall

0.8 0.85 0.9 0.95 1.0 1.05 2000 2100 2200 2300 2400 2500 incompleteness introduced by the different factors.

The fingerprint of RSD is evident in the 1DCRGHES Redshift flattening ofξ (rp,p) along the line-of-sight direction (left panel of Figure 4). This anisotropy yields a first estimate of the mean growth rate of structure, which is Comoving distance (Mpc/h) "NLNUHMFCHRS@MBD,OBG presented in de la Torre et al. (2013). The measured value is in agreement with the predictions of general relativity within the current uncertainty of ~ 17%. Com-

parison of the projected correlation functions wp(rp) (right panel, Figure 4) shows how well the measurements from the two independent fields agree, in both shape and amplitude. The final VIPERS catalogue will allow us to extend such measurements over two or more redshift bins.

Statistical errors will also be reduced by 0.5 0.55 0.6 0.65 0.7 0.75 measuring RSD with two independent

1300 1400 1500 1600 1700 1800 1900 galaxy populations (McDonald & Seljak, 2009), an important specific advantage allowed by the high sampling of VIPERS. Figure 2. The stunning view of the large-scale struc- Figure 3. Same as Figure 1, but for the W4 area. The ture of the Universe at 0.45 < z < 1.1, provided by the declination projection here is ~ 1.6 degrees. Figure 5 shows another way of using distribution of ~ 25 000 galaxies in the VIPERS W1 field (Guzzo et al., 2013). The opening angle the VIPERS data and quantifying galaxy corresponds to right ascension and the data are pro- clustering. The panels show different jected over ~ 1 degree in declination. The size of each Unveiling the structure of the younger estimates of the power spectrum P(k) dot is proportional to the galaxy B-band luminosity. Universe obtained from the de-projection of the angular clustering measured over the full The first immediate outcome of VIPERS is photometric parent sample of VIPERS Figure 1, has been frozen and is now shown by the maps of the galaxy distribu- i.e. the ~ 140 square degrees of the called the Public Data Release 1 (PDR-1) tion in Figures 2 and 3. The two cone dia- CFHTLS (Granett et al., 2012). This has catalogue. All data and analyses pre- grams present a remarkable combination been made possible by knowledge of sented in the journal papers recently sub- of volume and dynamical range (in terms the galaxy redshift distribution provided mitted for publication are based on this of scales sampled), which is a unique by an earlier version of the VIPERS cata- catalogue, which will become fully public achievement of VIPERS at these redshifts. logue. This measurement of P(k) has in September 2013. Here we present a They allow us to appreciate both the de been used to obtain improved constraints selection of these recent results. tails and the grand picture of large-scale on the number of neutrino species and

The Messenger 151 – March 2013 43 Astronomical Science Guzzo L. et al., VIPERS

10 "NLAHMDC6 6jDKCR 40 6jDKC 6jDKC L@RRMNMlKHMD@Q LNBJR 20 1 B ,O l Mpc) G

0 –1 O Q (h

O π V 0.1 –20

–40 0.01 –40 –20 0 20 40 r (h–1 Mpc) l p QOG ,OB

Figure 4. The redshift-space two-point correlation contours (de la Torre et al., 2013). Right: The projected Dark Matter model for the mass (dotted line, prediction function over the full 0.5 < z < 1.0 range, from the correlation function (obtained by integrating the data in using the HALOFIT code). The shaded area corre- VIPERS PDR-1 catalogue. Left: The 2D correlation the first quadrant of the upper figure along thep direc- sponds to the 1σ error corridor, computed from the function ξ(rp,p), showing the well-defined signature of tion), for W1 and W4 fields separately and for the total scatter in the measurements of a large set of mock linear redshift distortions, i.e. the oval shape of the sample. These are compared to the best-fittingΛ Cold surveys, custom built for VIPERS.

MFTK@QRB@KDCDFQDDR Figure 5. Early estimates of the real-space galaxy power spectrum P(k),through a combi "NLNUHMFCHRS@MBDGl,OB nation of the photo /J 10 metric data from the full /J '@KNjS CFHTLS area (140 square "NMUNKUDC/J '@KNjS

"NMUNKUDC/J+HMD@Q degrees) and the red-

$RSHL@SD shift distribution dN/dz

B from VIPERS (Granett et ,O al., 2012). The window l

G function of each band is J

/ shown in the panel 5(/$12lKHJD below each plot. The Y 2 YOGNS angular power spectrum is estimated from a VIPERS-like colour- selected sample (upper- HMC NV

6 left panel), and different slices in photometric redshifts are shown in the other three panels. The angular power spectrum is then de- projected to obtain the spatial power spectrum, knowing the dN/dz 2 Y 2 Y and selection function OGNS OGNS from VIPERS.

JG,OBl

44 The Messenger 151 – March 2013 Figure 6. Plot of the first four :.((< * ' eigenspectra obtained from the princi- '` ,F( pal component analysis of about %D( 'd 11000 VIPERS spectra (Marchetti et al., 2013). Each spectrum can be clas- 'b & A@MC :.(((< sified in terms of the amplitude of each "@ %D of its principal components, when it is decomposed into a linear combination of these. This technique allows us to 'a build a spectral classification scheme that is complementary to the SED- fitting technique. In contrast, specific spectra (such as those of active galac-

TW l tic nuclei) can also be spotted among

Dk l normal galaxies as not being well reproduced by the simple combination of the principal eigenvectors. 1DK@SHU l l l 6@UDKDMFSGÄ

their total mass (Xia et al., 2012). A direct bined to obtain, for all VIPERS galaxies, matter density parameter Ωm at z ~ 0.8 measurement of the 3D distribution of reliable spectral energy distribution (SED) (Bel et al., 2013), the luminosity depend- P(k) from the VIPERS redshift data alone fits and, in turn, luminosities and stellar ence of clustering (Marulli et al., 2013) is under development. masses. Figure 7 graphically shows the and the non-linearity of the galaxy biasing unique power of combining large-scale function (Di Porto et al., 2013), the evolu- (positions) and small-scale (here galaxy tion of the colour–magnitude relation and Pinpointing the properties of the galaxy colour) information: the fact that the col- luminosity function of galaxies (Fritz et al., population seven billion years ago our–density relation of galaxies is already 2013) and an automatic classification of in place at these redshifts is obvious stars, galaxies and active galactic nuclei Figure 6 refers to another recently pub- from this figure. Such a wealth of infor (AGN) based on Support Vector lished result, i.e., the decomposition of mation can be quantitatively encapsu- Machines (SVM; Malek et al., 2013). the first ~ 11 000 VIPERS spectra based lated by statistical measurements of the on principal component analysis (PCA; global population, to reveal overall evolu- The PDR-1 catalogue includes only Marchetti et al., 2013). The main goal here tionary trends. One such statistic is the ~ 60% of the final expected data. During has been to develop an objective classifi- galaxy stellar mass function; in Figure 8 the summer and autumn of 2012, 31 cation of galaxy spectra, capable of sepa- we show our estimate of this from the ad ditional pointings were observed, cover- rating different populations in a robust VIPERS PDR-1 catalogue and Davidzon ing another full row in W1 (the purple way. This will have applications for studies et al. (2013) provide more plots and and cyan fields in the upper panel of Fig- in both galaxy evolution and cosmology details. Given the volume of VIPERS, Fig- ure 1). These data are being processed (e.g., to define complementary large-scale ure 8 presents, without doubt, the most and, based on the usual yield, are ex structure tracers). The application of PCA precise estimate ever of the bright end pected to deliver around 11000 new red- to the whole PDR-1 sample is ongoing. of the mass function at z ~ 1 (Davidzon et shifts. With the current pace, we expect al., 2013), establishing a new reference spectroscopic observations at Paranal to As in the case of other deep surveys, for the mean density of massive galaxies be completed by 2014. an important feature of VIPERS is the at 0.5 < z < 1.2. complementary photometric information We can foresee a number of exciting over a wide wavelength range. For results being obtained from the VIPERS VIPERS, the five high-quality bands of the Further results and future perspectives data in the coming years, with many that CFHTLS have been further enriched with will originate from the general community, ultraviolet (UV; Galex) and near-infrared There are several other important results once the PDR-1 sample is in the public K-band (WIRCAM) photometric obser being obtained from the current VIPERS domain in September 2013. The grand vations. These measurements are com- data. These include an estimate of the view of large-scale structure in the young

The Messenger 151 – March 2013 45 Astronomical Science Guzzo L. et al., VIPERS

GL GL GL Figure 7. A zoom into the fine structure Acknowledgements of the W1 field galaxy distribution,

with an additional dimension provided We acknowledge the continuous support of the ESO by galaxy restframe colours. This pic- staff for all operations in Garching and at Paranal. ture gives an idea of the power of cou- We especially thank our project support astronomer, pling multiband photometry to galaxy Michael Hilker, for his enthusiastic contribution to all positions, when scales well above phases of the observation preparation and realisa- 100 h–1 Mpc are mapped. In this exam- tion chain.

ple, galaxies have been marked in red, green or blue, depending on their U–B restframe colour. In addition, the References size of each dot is proportional to the B-band luminosity of the correspond- Bel, J. & VIPERS Team, 2013, A&A, submitted

ing galaxy. The result shows, in all its de la Torre, S. & VIPERS Team, 2013, A&A, glory, the colour–density relation for submitted galaxies, already in place at these red- Colless, M. et al. 2001, MNRAS, 328, 1039 shifts, with red early-type galaxies Davidzon, I. & VIPERS Team, 2013, A&A, submitted tracing the backbone of structure and Di Porto, C. & VIPERS Team, 2013, A&A, submitted blue/green star-forming objects filling Eisenstein, D. et al. 2011, AJ, 142, 72

the more peripheral lower-density Fritz, A. & VIPERS Team, 2013, A&A, submitted regions. Garilli, B. et al. 2008, A&A, 486, 683 Garilli, B. et al. 2012, PASP, 124, 1232 Granett, B. J & VIPERS Team, 2012, MNRAS, 421, 251

1DCRGHES Guzzo, L. et al. 2008, Nature, 451, 541

Guzzo, L. & VIPERS Team, 2013, A&A, submitted Kaiser, N. 1987, MNRAS, 227, 1

"NLNUHMFCHRS@MBD,OBG Kauffmann, G. et al. 2003, MNRAS, 341, 54 Ilbert, O. et al. 2010, ApJ, 709, 644 Laureijs, R. et al. 2011, arXiv 1110.3193 Le Fevre, O. et al. 2005, A&A, 439, 845

Lilly, S. J. et al. 2009, ApJS, 184, 218 Malek, K. & VIPERS Team, 2013, A&A, submitted Marchetti, A. & VIPERS Team, 2013, MNRAS, 426, 1424 Marulli, F. & VIPERS Team, 2013, A&A, submitted McDonald, P. & Seljak, U. 2009, JCAP, 10, 007

Peacock, J. A. et al. 2001, Nature, 410, 169 Peebles, P. J. E. 1980, The Large-Scale Structure of the Universe, (Princeton: Princeton University Press) Pozzetti, L. et al. 2007, A&A, 474, 443 Pozzetti, L. et al. 2010, A&A, 523, 10 Scodeggio, M. et al. 2009, The Messenger, 135, 13

Xia, J.-Q. et al. 2012, JCAP, 06, 010

Links Universe provided by the first data we will be those that were not even men- have discussed here, makes us hope that tioned in the original proposal, but are 1 CFHTLS: http://www.cfht.hawaii.edu/Science/ — as has happened with previous red- there awaiting us, written inside the large- CFHLS/ 2 shift surveys — the most exciting results scale distribution of galaxies. VIPERS public web pages: http://vipers.inaf.it

Figure 8. The VIPERS galaxy stel- Y Y Y lar mass function (MF) at three ref-

l erence redshifts, estimated from W l the PDR-1 catalogue (blue points CD with error corridor, Davidzon l et al., 2013). Comparison is pro- OB l vided with previous estimates from , 5(/$12 5(/$12 5(/$12 two spectroscopic VLT surveys

G 55#2 55#2 55#2 (Pozzetti et al., 2007; 2010) and Y".2,.2 Y".2,.2 Y".2,.2 from the COSMOS photo-z sample \ l (Ilbert et al., 2010). Note the small

F ".2,.2 ".2,.2 ".2,.2 size of the error corridor, indicating KN how, at large masses, VIPERS is l providing a remarkably precise measurement for these redshifts, l owing to its large volume. KNF, G ,ी

46 The Messenger 151 – March 2013 eso1305. Release See (left). Zeeuw de Tim General, Director ESO the by accompanied shown is 2013 and January in Paranal visited Barroso, Manuel José The President of the European Commission,

European Commission/ESO ment ann12097. Announce See (right). Tarenghi Massimo Chile, in ESO’s Representative with pictured are and 2012 December in offices Santiago ESO visited early March 2013. from image this in apparent is extension quarters Head ESO the of construction the of Progress Dr Heinz Fischer, and his wife Margit Fischer Fischer Margit wife his and Fischer, Heinz Dr Austria, of Republic the of President Federal The

- Astronomical News Astronomical News

Report on the Workshop Ecology of Blue Straggler Stars held at ESO Vitacura, Santiago, Chile, 5–9 November 2012

Henri Boffin1 systems, stellar evolution and stellar (talk by F. Ferraro), in open clusters (talks Giovanni Carraro1 populations, as well as the dynamics of by R. Mathieu and J. Ahumada) and in Giacomo Beccari 1 clusters. The chosen format of the event nearby dwarf galaxies (Y. Momany). Field (i.e., a low number of participants and a blue stragglers have also been identified large amount of time devoted to discus- from their anomalous kinematics and 1 ESO sion) resulted in a very lively workshop, chemical abundances (G. Preston). These which was much appreciated by the par- reviews revealed the fantastic advances ticipants. The discussions were triggered made in the field in the past decades. The last workshop dedicated to by the very detailed and useful invited blue straggler stars (BSS) took place talks — no less than 12 were given — Ferraro and his group discussed the chal- 20 years ago and there have been a providing a unique and insightful view on lenges associated with observing these great number of subsequent develop- the field. relatively faint stars in overcrowded stellar ments since in both observations and regions, such as the cores of globular theory. The wide range of BSS topics The introductory talk by R. Cannon clusters, and the key advances obtained covered at the workshop are briefly reminded us of the first discovery of blue through high-resolution ultraviolet (UV) summarised; the published proceed- straggler stars in 1953 by Alan Sandage photometry. The speakers provided de ings will form the first book on the sub- in the globular cluster M53, as well as the tailed evidence that BSS are a common ject. fact that the only previous proper work- population found in each globular cluster shop on BSS took place in October 1992, properly observed, with some clusters at the Space Telescope Institute, i.e. (e.g., M80) having more than 100 identi- The existence of blue straggler stars 20 years ago! It was also Cannon who fied BSS. The observations of many (BSS), which appear younger, hotter, and recalled that the germ of the idea that clusters allow a comparative analysis of more massive than their siblings, is BSS are due to binaries was planted by BSS in globular clusters with different at odds with a simple picture of stellar none other than Fred Hoyle, only two physical parameters to be made, show- evolution, as such stars should have years after their discovery, as well as ing the clear connection that is emerging exhausted their nuclear fuel and evolved by John Crawford in the same year, and between BSS properties and the parent long ago to become cooling white dwarfs. then further developed by William cluster dynamical evolution. Indeed, With the many advances in observational McCrea in 1964. the shape of the BSS radial distribution and theoretical work on blue straggler provides a record of the degree of dynam- stars, the time was considered ripe for ical evolution experienced to date by a dedicated workshop to summarise Observations of BSS the p arent cluster, indicating how efficient the current state of the field, identify dynamical friction has been, while the the many still open questions and define As is typical for astronomical confer- presence of double BSS sequences in in a coordinated way new avenues of ences, the first few days were dedicated research to address these issues. The to a review of the observational evidence, resulting workshop brought together clearly demonstrating that BSS are ubiq- Figure 1. The conference photograph spec ialists in binaries and multiple star uitous: they exist in globular clusters in the grounds of ESO Vitacura.

48 The Messenger 151 – March 2013 the colour–magnitude diagram could tes- seem to indicate that mass transfer from As R. Cannon also reminded us during tify to, and even date, the occurrence of a giant star may be much more stable his introductory talk, the few good re- the cluster core collapse event. Ferraro’s than previously thought, leaving a much views about BSS date back to the 1990s group also presented exhaustive chemical wider parameter range to explain the and no dedicated book exists on this and kinematical analysis of BSS in globu- existence of BSS. However, it is not cer- exciting topic. We have thus decided to lar clusters. tain that this mass transfer happens early remedy this situation and make use of enough that plenty of mass is still availa- the unique expertise gathered by the R. Mathieu presented a fine study of ble to be transferred, a pre-requisite for a workshop to produce the first ever book the BSS population in the open cluster BSS. dedicated to BSS. The book will be pub- NGC 188, allowing him and his col- lished by Springer in its Astronomy and leagues to perform “micro-astronomics”, H. Perets, M. Davies and A. Geller Astrophysics Library Series and will con- i.e., determination of the binary frequency presented the possible formation chan- tain major chapters from all the invited and study of the distributions of the nels for BSS in various environments, speakers, edited by us. We aim at pro- orbital parameters (period, eccentricity S. McMillan reviewed the dynamical evo- ducing a book that will appeal to a large and secondary mass). G. Preston did lution of globular clusters and how BSS community of researchers and especially the same for the BSS in the field, and the fit into the picture, while C. Knigge and to graduate students. The book should conclusion of both these studies is that A. Sills showed detailed confrontations appear by the year’s end. In the mean- BSS present a high binary fraction, with between the theory and observations. In time, you can still view the presentations orbital periods of 1000 days, low orbital some cases, data exist that are precise and watch some of the recorded talks on eccentricities and typical secondary enough to derive detailed information on the conference web page1. masses of 0.5 MA. Whether this is similar the characteristics of some blue straggler to the population of BSS in globular systems (namely mass, temperature and clusters is still unknown, but such prop- luminosity), to enable comparison with Acknowledgements erties are, as explained by H. Boffin, very evolutionary tracks and mass transfer It is a pleasure to thank all the participants for con- reminiscent of the population of barium modelling. There were indeed a few sur- tributing so actively to the workshop, and especially and other peculiar red giant stars, and prises: as several reviewers indicated, it the invited speakers for providing very clear and thus possibly the result of wind mass is still unclear how to produce BSS with exhaustive reviews of their respective areas. Special transfer from an asymptotic giant branch their observed luminosities, which appear thanks go to Bob Mathieu for providing an illuminat- ing and entertaining summary talk, from which we (AGB) star. The fact that most field BSS to be much too low for their mass, or unashamedly borrowed to write the present report. are s-process enriched — the exact sig- how one can even produce BSS with Warm thanks also go to the Local Organising Com- nature of barium stars — is thus perhaps such high masses. Similarly, it was gen- mittee for the smooth organisation of the workshop. no surprise, even though much more erally assumed that two mechanisms work is required to connect the two cate- were responsible for blue straggler stars Links gories of stars. — merger and mass transfer — both of which can operate in the same cluster: 1 Ecology of BSS workshop pages: http://www.eso. the exact preponderance of one mech org/sci/meetings/2012/bss2012.html Interpreting BSS anism over the other possibly depending on the cluster’s property, that is, the blue Following the observational talks, the straggler’s ecology. The wealth of obser- next days were devoted to the theory and vations reviewed during the workshop the interpretation of the data. As men- showed that it is still impossible to con- tioned, Boffin reviewed the scenario of clude whether stellar collisions do occur, mass transfer by winds, while N. Ivanova and could create some BSS. More work covered Roche lobe overflow. If the latter is clearly still required in this area. mass transfer scenario is most likely to occur in the very short period systems The last invited talk, by L. Deng, showed (with orbital period of a few days or less), the importance of BSS in stellar popu the crucial question is to know under lation synthesis, and how the presence which conditions mass transfer from an of BSS can dramatically alter the observ AGB star could be stable, so as to avoid ables of distant systems — their neglect the common-envelope (CE) phase. For- can lead to large errors in the inferred mation of a CE is thought to cause a dra- spectrophotometric properties of galax- matic shrinkage of the orbit and thus ies. The last word was given to R. Mathieu would not allow the long orbital periods who brilliantly summarised the workshop observed in open clusters to be explained. and led the final discussion. The recent results from Ivanova’s group

The Messenger 151 – March 2013 49 Astronomical News

Report on the Conference The First Year of ALMA Science held at Puerto Varas, Chile , 12–15 December 2012

Leonardo Testi1 Paola Andreani1

1 ESO

The conference reviewed the scientific results of the first year of ALMA Early Science operations and a summary of the highlights is presented. All areas of ALMA Cycle 0 science were covered, with emphasis on new results for astrochemistry, the Solar System, star and planet formation, the life cycle of stars, nearby galaxies, active galactic nuclei and the high redshift Universe. The pri- orities and prospects for ALMA Full Science and ALMA upgrades were also discussed.

ALMA Early Science Operations Cycle 0 observations started on 30 September Figure 1. The participants at the First Year of ALMA 2011. Before then, in spring and summer Science conference held in Puerto Varas, Chile. 2011, the observatory had started to release science-qualified Science Verifi- Raphael Bachiller (Director of the Obser- mately 100 posters on observational, cation (SV) datasets. The first scientific vatorio Astronómico Nacional [OAN] theoretical and instrumental topics con- papers based on ALMA data started to in Madrid, ESO Council Member and nected with ALMA. Below we provide a appear in press at the beginning of 2012. Chairman of the Radionet-3 Board) and short summary of the main science high- Since the Cycle 0 observation season Juan Cortes of the Joint ALMA Obser lights; the programme is available on the was completed at the beginning of 2013 vatory (JAO) presenting the ALMA project conference web page1. (see Zwaan et al. p. 20), December 2012 and its science objectives to the general was perfect timing to review the first public. ALMA science results in a dedicated con- Astrochemistry ference. The promise of ALMA was to revolution- ise many scientific areas by providing an Astrochemistry was one of the main The conference was co-organised and unprecedented quantity and quality of recurring topics in the conference, across co-sponsored by all the ALMA partners, high spatial and spectral resolution (sub) all the science areas. ALMA’s sensitivity with an important additional contribution millimetre wavelength spectral line data. has transformed the field of astrochemis- from the European Commission FP7 The ALMA challenge is then to allow try from the confines of exotic Galactic Radionet-3 project. 199 astronomers observers to perform detailed tests of sources and a few starburst galaxies to a from all over the world gathered in the astrochemical models, star and planet theme that encompasses all areas of beautiful setting of the town of Puerto formation, galaxy formation and evolu- ALMA science. Different chemical evolu- Varas in southern Chile to discuss ALMA tion, and many other investigations. tionary paths during the formation of science (see Figure 1). Senior astrono- Throughout the conference, the transfor- proto stars were discussed at the confer- mers and many young students and mational power of ALMA data, even with ence: the new ALMA data are highlighting postdocs shared their enthusiasm over the limited capabilities available so far not only the distinction between “hot the first ALMA results. Thijs de Graauw, during SV and Cycle 0, were emphasised corino” and “warm carbon chain chemis- Massimo Tarenghi and Pierre Cox, cur- many times. The enormous progress in try” protostars, which need to be under- rent, previous and future ALMA Directors sensitivity and image fidelity provided by stood and reconciled in a common respectively, addressed the participants, ALMA, even at these early stages, was framework, but also the chemical com- sharing with them their insights and clearly demonstrated. plexity of the interplay between dust, ices reflections on the initial phases of con- and different molecular species and struction, the excitement of delivering the The science programme for the confer- isotopologues in the path from clouds to first science observations and the great ence included eight overview talks intro- planetary systems. expectations for future science results. ducing the different areas of ALMA sci- Two public evenings were also organised ence, 43 oral contributions, all presenting The chemistry of deuterated and complex as part of the conference events, with results from ALMA data, and approxi- organic molecules in protostars and discs

50 The Messenger 151 – March 2013 ŻP ǥ *+] ࣳ @A ¦ ǥ 5 ,) +2 ࣳ X 1 ǥ RS JL DQ

¦ ࣳ &,, ) @C ) b R b ¦ ǥ ǥ

ࣳ SF ࣳ ¦ G L R R G L R R G L R R R

¦ _) _)

Figure 2. The candidate Keplerian disc around a filled circles showing the displacement of the photo- of vibrationally excited methanol (CH3OH) and the massive (proto-)stellar system in G35.20-0.74N. In centre in various velocity channels and the coloured HC3N molecule, both spatially and kinematically, at the left panel, the ALMA 350 GHz continuum emis- contours showing the full width at half maximum sub-arcsecond resolution. These complex organic sion (green contours) is overlaid on the 4.5 μm of the emission in each of the velocity channels. To molecules trace the inner few thousand astronomical Spitzer image. The right panels show the kinematical the right is shown the comparison to a disc with a units of a disc that is well modelled by the Keplerian

analysis of the disc. To the left is shown the result Keplerian velocity pattern. ALMA resolves the emis- rotation pattern orbiting a central mass of 18 MA. of the kinematical analysis of the molecular line data sion from several components of the (19-18) transi- Figure adapted from Sánchez-Monge et al. (2013),

towards the hot core (B) in this region with the small tion of methyl cyanide (CH3CN), as well as transitions in press.

was a major discussion topic, with talks Herschel–ALMA study of the great storm of the collapsing envelope within the cen- and posters showing the mapping of in Saturn’s atmosphere was also pre- tral 30–40 AU, an indication of a small water isotopes and deuterated species in sented. The analysis of the data from the inner disc in Keplerian rotation around the the planet-forming regions of discs. In two observatories confirms that, while the central protostar. a young solar analogue a simple sugar, differing CO intensity inside and outside glycolaldehyde, has been detected (see the storm is just caused by a higher tem- The quest for the initial conditions for Release eso1234), which is thought to perature within the storm and not by an high-mass star formation has already

be an essential step in developing biotic abundance variation, the H2O abundance been brought to a new level with ALMA, molecules, in particular the RNA mole- in the storm is higher than in the rest of where detailed studies of different can cule. The impact of astrochemistry on the stratosphere of the planet and was didates across the Galaxy provide critical extragalactic studies was also highlighted probably caused by the vapourisation of data that can now be directly compared by the Cycle 0 observations of nearby icy clouds and enrichment with material with numerical models. The role of discs and high-redshift galaxies, which at the from the O-rich troposphere. Much pro- and outflows and their structure in the ALMA sensitivity are now showing emis- gress is expected to come from the study formation of highest-mass stars was also sion from many of the complex and less of the chemical composition of comets, addressed. Tantalising new evidence for abundant molecules that have, so far, which should provide important con- Keplerian discs surrounding very massive been mostly studied in our own Galactic straints on the origin of water and, possi- protostellar candidates provides direct environment. bly, complex organic molecules on Earth. constraints on the formation mechanism (see Figure 2 for an example). The high angular resolution, sensitivity and wide- Solar System science Star formation area interferometric mapping capabilities of ALMA are also proving to be a key The power of ALMA to study and under- Besides the chemical studies, ALMA is tool to understand the formation of very stand the atmospheres and surfaces of now providing new insights on the physi- massive clusters, both in our Galaxy and bodies in our own Solar System was cal and kinematical structure of proto- in the Local Universe. The spectacular reviewed. Some of the main topics where stars and young stellar objects. The first images of a proto young massive-cluster ALMA is expected to make a contribu- hints that ALMA has started to address candidate near the Galactic Centre re- tion are in the characterisation of the directly the long-standing problem of the veal for the first time a chemical, physical chemical composition and seasonal vari- kinematical signature of disc formation and kinematical complexity that will keep ation of the atmospheres of planets during protostellar collapse was pre- both observers and theorists occupied and moons, and preliminary ALMA maps sented at the meeting. Detailed analysis for several years. of Venus and Titan illustrated this point. of the CO isotopes in Class 0 protostars A detailed analysis of a combined reveals a possible break in the kinematics

The Messenger 151 – March 2013 51 Astronomical News Testi L., Andreani P., Report on the Conference “The First Year of ALMA Science”

Planet formation regions of the system (see Figure 3 and Galaxy formation Release eso1301). The dust asymmetries Several new ALMA Cycle 0 results were are interpreted as the effect of a planet In the nearby Universe there is the poten- presented on the structure and evolu- that induces an asymmetric pressure var- tial for ALMA to directly study the sites tion of protoplanetary discs and the impli- iation in the outer disc, creating an effi- of star formation, i.e. giant molecular cations for the formation of planetary cient trap for dust grains. The ALMA sen- clouds (GMCs), in order to derive the star systems. Observations of dust evolution sitivity and angular resolution also allows formation efficiency and the gas deple- in discs around very low-mass stars and the direct detection of the CO-emitting tion time on sub-galactic scales. These brown dwarfs with ALMA cannot easily layer in the large disc around HD 163296 can be related to galaxy properties, such be explained with the existing dust evolu- and to directly constrain the flaring of the as metallicity, cloud densities and pres- tion models, suggesting that our under- disc in molecular gas. sures, and velocity dispersions. Some standing of the processes governing dust nearby galaxies have already been targets evolution in discs is not complete (see of ALMA SV projects. The impressive Release eso1248). The detection of CO in Stellar evolution M100 large-scale mosaic shows that CO several of these discs around young emission traces a two-armed spiral and brown dwarfs confirms that some of ALMA can also provide new constraints, a double bar out to 10 kpc and that the these are indeed surrounded by relatively not only on the cool side of the Universe, time needed for the current star forma- large and massive discs. but also on the hot atmospheres of stars. tion rate to consume the existing gas Multi-wavelength observations at centi- reser voir is 1.7–1.9 Gyr. Even in Cycle 0, ALMA has already metre and millimetre wavelengths of the started to transform the field of planet stellar chromospheres can allow the Molecular gas fragmentation has been formation. The sensitivity of ALMA in amount of magnetic heating in stars to be observed to occur at parsec (pc) scales the high frequency bands, as compared probed. For this reason, its capability to along filamentary structures in NGC 253, to the previous facilities, has allowed observe the Sun is one of the key fea- the Antennae Galaxy and 30 Doradus. high quality images to be obtained of the tures of ALMA, and has been designed At galactic scales, the parents of these asymmetries in the dust distribution and into the system from the very beginning filamentary structures are GMCs, with 5–6 quantitative measurement of the gas con- of the project. While observations of the masses of ~ 10 MA and sizes of tens of tent in the inner dust-evacuated holes of Sun are still being tested and commis- pc. These are found in spiral galaxies and evolved discs. The data reveal indirectly sioned, ALMA has been observing differ- in the interarm region of the overlap of the presence of forming planets and con- ent phases of stellar evolution from the the arms of the Antennae. A newly discov- strain the flow of material from the outer beginning of Cycle 0. Millimetre flares in ered tidal filamentary arm was presented disc through the planet and into the inner young stellar objects have been recently in NGC 4039, 3.4 kpc long and < 200 pc observed and will become an impor- wide, where the star formation efficiency is tant topic for ALMA science owing to the a factor of ten larger than in disc galaxies. high sensitivity available. ALMA’s resolution also enables details of Millimetre continuum observations will the centres of nearby mergers to be also be critical to separate the non- probed. Double nuclei have been detected thermal emission from the coronae and in NGC 3256, similar to those in Arp 220, the stellar wind components, allowing while in NGC 34 (a luminous infrared direct measurements of the mass loss in galaxy with an active galactic nucleus stars of various masses and ages. Initial [AGN]) Band 9 CO(6–5) observations are

ALMA (ESO/NAOJ/NRAO), S. Casassus et al. results in this area are expected from consistent with two nuclei: one assoc Cycle 1 programmes. In Cycle 0, several iated with a starburst and another with programmes focused on the study of the AGN. the mass loss in the late stages of evolved stars. Observations of stars in the late Several presentations clearly pointed out stages of stellar evolution provide con- the fundamental contribution that ALMA straints on the chemical enrichment of the is providing to the field of galaxy forma- Figure 3. The disc around the young star HD 142527 interstellar medium. Some of the most tion in addressing the major mechanisms: + shown in a montage of HCO (4-3) and CO(3-2) emis- spectacular ALMA data on the late stages merger and starburst-driven or governed sion and dust continuum, highlighting the streams of gas flowing across the gap in the disc. The dust of stellar evolution presented at the meet- by secular evolution. An initial attempt to emission in the outer disc is shown in red, dense gas ing included: the mass-loss history follow- answer some specific questions was car- in the streams flowing across the gap, as well as ing the thermal pulse in the asymptotic ried out by the LESS and COSMOS con- + in the outer disc, is shown in green (HCO emission), giant branch star RScl (see ESO release tinuum surveys with the determination of and diffuse gas in the central gap in blue (CO). The gas filaments can be seen at the three o’clock and eso1239 and the cover of The Messenger galaxy counts. These surveys also enable ten o’clock positions. From Casassus et al. 2013; 149) and detection of the dust, CO and better estimation of the spectral energy see Release eso1301 for more details. SiO emission in the ejecta of SN 1987A in distribution (SED) of galaxies, and there- the Large Magellanic Cloud. fore of the dust mass and gas fraction.

52 The Messenger 151 – March 2013 Active galactic nuclei ALMA is able to put strong constraints on infrared/millimetre range, and at z > 5 the the presence of cool dust and star form line is redshifted into ALMA bands. ALMA One of the biggest puzzles in active ation, and to confirm that this sample can detect [C ii] from a galaxy with a star galactic nuclei physics is the removal of consists of heavily obscured Type 2 qua- formation rate of only 5 MA/yr at z = 7 the angular momentum from the disc sars, often Compton-thick and very in 1 hour (5σ in two channels). Further- gas and mechanisms driving infall down strongly AGN-dominated; some sources more, in low metallicity systems, as high-z to the nucleus on scales of tens of par- do not show any evidence of star form objects are expected to be, the ratio secs. Simulations suggest a role for gal- ation. [C ii]/far-infrared is larger, i.e. increases axy bars, but no correlation between with decreasing metallicity. Outflows can AGN activity and bars is seen. New The environment around galaxies, such also be detected in such distant galaxies, ALMA results for two sources (NGC 1433 as the X-ray cavities in galaxy clusters as revealed by [C ii] emission line pro- and NGC 1566) show that the dense provides good locations for measuring files in a z = 6.4 quasar with velocities molecular gas seems to fall into the the mechanical power injected by the > 1000 km/s, size > 10 kpc and an out- nucleus at the unprecedented spatial res- SMBH. AGN heating is energetically suf flow mass rate of ~ 3000 MA/yr. The gas olution of 24 pc. The kinematics of the ficient to offset radiative cooling in galaxy consumption timescale due to outflow nuclear spiral arms in NGC 1097 have cluster cores and can be coupled to the may be less than the star formation time- been followed down to ~ 50 pc from the cooling gas and therefore to feedback. scale, highlighting the “quasar-mode” central supermassive black hole (SMBH) CO has been detected in the centre of feedback process which inhibits further from the ALMA detection of HCN, a two nearby clusters with extreme X-ray star formation and enriches the local tracer of high density gas. cooling rates; a radiative cooling time intergalactic medium. < 1 Gyr and a star formation rate of

Absorption lines in the spectra of AGN, 10–100MA/yr for the central radio galaxy the nearby Centaurus-A (Cen-A) and were derived. The bulk of the cold gas Gravitational lenses PKS1830-211 at z = 0.886, were also is centrally condensed and has a similar shown. Such investigations offer a unique spatial extent to the star formation. The flux magnification provided by gravi- opportunity to find gas that might be tational lensing enabled a spectroscopic feeding the AGN. Towards the SMBH of Observations of two extremely obscured redshift survey with ALMA to be per- Cen-A, the gas becomes denser, warmer luminous infrared galaxies (LIRGs) with formed in Cycle 0, targeting 26 sources and influenced by the presence of pho- very large obscuration and hidden com- from the South Pole Telescope using CO ton dissociation regions (PDRs). Detailed pact infrared cores show a rich, hot-core- line detections (see Figure 4). 40% of study of absorption lines towards AGN like chemistry with vibrationally excited these sources lie at z > 4. It appears that reveals the chemical enrichment of the HC3N, HNC and HCN. In NGC 1266, an the fraction of dusty starburst galaxies Universe through isotopic ratios and can interacting galaxy, we are witnessing a at high redshift is far higher than previ- constrain the constancy of fundamental rapid cessation of star formation, with a ously thought. Two sources were found constants by detecting line shifts with dense molecular gas outflow rate of at z = 5.7, placing them among the respect to laboratory measurements, ~ 100 MA/yr, much larger than the star highest redshift starbursts known, and such as in PKS1830-211, where ALMA formation rate. An AGN is the likely driver demonstrating that large reservoirs of observations include water in absorption. of the outflow, and shocked molecular molecular gas and dust can be present in gas is located near the launch point of massive galaxies near the end of the Molecular outflows may be associated the outflow, as seen in ALMA multi-transi- epoch of cosmic reionisation. The ALMA with AGN activity or with vigorous star- tion SiO observations. The detection of detection of the arcs and source images bursts and have been detected with other molecular species with ALMA will of a beautiful gravitational lens, g15.v2.19, ALMA in HCO+(4-3) and CO(3-2) through help build a more complete chemical pic- was also shown and discussed. their high-velocity wings. In the centre ture of NGC 1266. of NGC 253, the ALMA detection of the H40α line in a molecular outflow raises Prize poster competition the question of the mechanism for effi- High redshift sources cient transfer of angular momentum to Given the large number of young partici- the molecular gas. Several talks pointed The redshifts of very high-z (z > 5) galax- pating students and postdocs, who out the need to measure outflow rates ies leads to fuller understanding of the presented many excellent results in the of cold gas and test star formation and objects responsible for the reionisation of poster sessions, the Scientific Organising AGN feedback models. A key issue is the Universe. Their redshifts can be Committee decided to organise a com- the investigation of the processes that determined through detection of the [C ii] petition for the best posters amongst quench star formation and turn galaxies line, which is the principal interstellar them. The poster prize committee, com- into “red and dead”. New ALMA results medium gas coolant, traces PDRs, and posed of the overview speakers and were presented on a sample of extremely warm intergalactic and circumnuclear the project scientists, awarded three rare ultra/hyper-luminous very red radio- media, and CO lines (see Figure 4 for an prizes for the best science posters to: loud quasars, which are considered young example). [C ii] is up to ten times more E. Akiyama for the analysis of the SV data jet feedback candidates at z = 0.5–3. luminous than any other line in the far on the protoplanetary disc around the

The Messenger 151 – March 2013 53 Astronomical News Testi L., Andreani P., Report on the Conference “The First Year of ALMA Science”

z = 3.369 z = 4.296 CO(5–4) 20 20 CO(4–3) CO(4–3) CI(1–0) ) 13CO(4–3) Jy

(m 10 10 v

0 0

z = 4.567 CO(5–4) z = 5.656 20 20 CO(5–4) CO(6–5) p–H2O(211–202)

)S + H2O Jy

(m 10 10 v CI(1–0) S

0 0

90 100110 90 100110

vobs (GHz) vobs (GHz)

Figure 4. Example ALMA Band 3 spectra of gravita- of the ALMA data, and a copy of the Gregorio Monsalvo, Violette Impellizeri, tionally lensed submillimetre galaxies selected from book Cerca del cielo, to remind them of Hanifa Nalubowa, and Gautier Mathys the South Pole Telescope survey (Weiss et al., 2013). The spectra demonstrate the sensitivity of ALMA the beauty and biological richness of the (chair). The conference was co-spon- and the richness of the survey with detections of region of northern Chile that hosts the sored by ESO, NAOJ, NRAO, the EC-FP7 12 13 + CO, CO, C i, H2O and H2O . ALMA Observatory. Two posters describ- Radionet-3 project and CONYCIT. ing important technical developments intermediate-mass pre-main sequence for ALMA also received a special men- star HD 163296; R. Herrera-Camus, tion: A. Avison for his work on the Obser- References for the important work on the calibration vation Support Tool and H. Nagai for the Casassus, S. et al. 2013, Nature, 493, 191 of the [C ii] line as a star formation tracer description of the status of ALMA polari- Sánchez-Monge, Á. et al. 2013, A&A, in press in the deep Universe; and M. McCoy sation observations. Weiss, A. et al. 2013, ApJ, in press for the study on the Early Science ab sorption spectrum of the nearby active The practical organisation of the meeting Links galactic nucleus of Cen-A. Each of the was a great success, thanks to the three winners received an ALMA coffee efforts of the local organising committee 1 First Year of ALMA Science conference website: mug, as a useful tool for the long hours at the JAO: Mariluz Calderón, Ann http://www.almasc.org/ to be spent on the scientific interpretation Edmunds, Valeria Foncea, Itziar de

A recent view of the Chajnantor Plateau ESO/B. Tafreshi (twanight.org) and ALMA taken from the nearby peak of Cerro Chico. See Picture of the Week 24 December 2012 (potw1252a).

54 The Messenger 151 – March 2013 Astronomical News

Report on the ESO Workshop Real Time Control for Adaptive Optics 2012

held at ESO Garching, Germany, 4–5 December 2012

Enrico Fedrigo1 Facts and figures designed a custom board populated by a large number of FPGA chips. Some- This was the second in a series of Real thing similar was made by Microgate 1 ESO Time Control for AO workshops; the [presented by Biasi], with custom boards first was held in Durham in April 20111. made with both FPGA and DSPs (Digital Sixty-six outside participants, com Signal Processors), the latter a technol- The Real Time Control for Adaptive plemented by a number of ESO staff ogy that does not seem to hold any pros- Optics workshop series was conceived members, attended the 2012 workshop: pects for the future. SPARTA3 for the to bring together international special the 28 talks were divided into seven VLT also contains FPGAs and DSPs ists in real-time control (RTC) for sessions and there was one panel and [Suarez], integrated in commercial boards. adaptive optics in order to share and two open discussions (access the work- exchange experience regarding the shop programme via the QR code [Fig- While recognising the value of predictabil- design and implementation of these ure 1] or directly via the web page2). Most ity and determinism, important for multi- systems. During two full days, the par- of the participants were European (see year development projects, the panel dis- ticipants were presented with 28 talks the breakdown in Figure 2), with about cussion immediately pointed out the divided into seven sessions, one panel 10% non-European participants (USA, main problem with this technology, which discussion and two free-form open Canada, east Russia), and almost 20% is the long round-trip engineering cycle discussions. The major topics covered of the participants were from industry, required to develop under FPGAs. This during this second RTC workshop are all former or current ESO partners. The aspect was exacerbated in ESO’s SPARTA briefly reported. workshop also invited participants to a project, as all FPGA development is out- social dinner in true Bavarian style at the sourced and therefore any new require- Augustiner restaurant in central Munich, ment takes a long time to be completed, The real-time control system is a crucial surrounded by the warm atmosphere of mostly due to contractual issues. With component for any astronomical adaptive the Christkindl open-air market. respect to this point, some talks [Dipper] optics (AO) system. The computational identified the Open Computing Language demands placed on the next generation (OpenCL) framework as a promising ap RTCs for future extremely large tele- Technology proach for enhancing FPGA design pro- scopes (ELTs) are enormous, and even ductivity that would, at the same time, current systems require specialised skills The major topics covered in the work- unify the development between FPGAs, to implement. The workshop series shop were technology and algorithms, GPUs and the advanced mathematical brings together international AO RTC the former divided into three techno units of the CPUs. specialists with the aim of sharing and logical families: Central Processing Units exchanging experience in order to im (CPUs), Graphical Processing Units The second family of technology that prove the design of new and proposed (GPUs) and Field Programmable Gate was considered is the GPU, or rather AO systems, increasing their perfor- Arrays (FPGAs). Different groups took dif- General Purpose Graphical Processing mance and usability. Although the work- ferent approaches and none was really Unit (GP-GPU), currently being looked shops are focused principally on astro- identified as the “silver bullet”. FPGAs are at by many groups. When used in real nomical AO, attendance of participants components that can execute a program time, this approach suffers from the com- from non-astronomical areas, including at hardware level and are therefore poten- puting model offered by the GPU cards industry, was welcomed, and indeed tially very fast but, above all, extremely presently on the market: no on-board encouraged, to allow cross-disciplinary deterministic, since every phase of the input/output is featured and they must discussions to take place. process is under the control of the pro- receive data from the central processing grammer. This is the approach taken unit and its memory. Recent develop- Figure 1. The QR code used to announce the by one group at the Thirty Meter Tele- ments such as NVIDIA GPUDirect [talks website2 of the RTC Workshop 2012. scope (TMT) project [talk by Ljusic] who by Gratadour and Dipper] promise to

USA Canada United Kingdom 4% 3% 15% Austria Denmark The 11% 3% Netherlands 6% France Spain 14 % 1% Germany Russia Italy 17 % 23% 3% Figure 2. The breakdown of participants to the second Real Time Con- trol for Adaptive Optics workshop.

The Messenger 151 – March 2013 55 Astronomical News Fedrigo E., Report on the ESO Conference “Real Time Control for AO 2012”

alleviate some of the problems. Several all-CPU system, from solar astronomy at SPIE 2010 meeting. The main idea is to prototypes and projects were presented the Kiepenheuer Institute (Linux, ~ 500 maximise the reuse of the SPARTA archi- by LESIA [Sevin, Gratadour], another subapertures; with plans to switch to the tecture and software to achieve the high- group from TMT [Wang] and the Dutch higher performance FPGA for the future est cost-saving possible, while abandon- Organization for Applied Scientific 1600-subaperture system, [Bekerfeld]), ing the VMEbus in favour of using Research [TNO; Doelman], the latter pro- to Force Technology (FreeBSD, with 2500 server-class systems to host accelerators jecting a possible GPU-based system subapertures, [Kamp]), to the Durham of various types, or even just using the for an instrument of the size of the E-ELT DARC real-time controller (Linux, with available plain CPU to achieve lower Exoplanet Imaging Camera and Spectro- ~ 200 subapertures, [Basden]), to the all- hardware costs and better maintenance graph (EPICS; see Kasper & Beuzit, CPU version of ESO’s SPARTA running capability. 2010). on the Intel version of the real time operating system VxWorks (1300 subaper- However, even though of a different mag- tures, [Tischer]). Algorithms nitude, GPUs suffer from a similar problem to the FPGAs: they need specialised The clear advantage of all-CPU systems The other major topic of the workshop tools and specialised knowledge to really is the ease of programming and the short concerned which algorithm a real-time harness the computing power available. development time required to achieve controller should implement. A typical GPUs are now very common; so many a minimum functionality. This was clearly measure of the complexity of an AO RTC libraries are available to implement stand- demonstrated by the Durham system is the product of the number of degrees ard algorithms, without the need to learn where a number of strategies and algo- of freedom at the input (the total number a new technology. Also mentioned in rithms were prototyped and tested of gradients, or double the number of several talks was the upcoming Intel Phi [ Basden]. What it takes to scale the sys- subapertures), the number of degrees of [Dipper, Gratadour], the first instance tem up is more debatable: how to tune it freedom at the output (the total number of the new Intel many-core architecture. It to the best performance possible and of mirror actuators) and the sampling shares several aspects of a GPU since move the implementation from prototype rate. Without going into the details of it sits on the same peripheral component to production. The major issue with this latency requirements [as discussed by interconnect (PCI) bus and acts as an approach might not be the debate about Fedrigo], this measure defines the mini- accelerator without dedicated input/out- whether performance can come by mum computing power required, assum- put. However inside it is a many-core tweaking and hacking a freely available ing a standard least squares estimate system, so will be something potentially operating system or by purchasing an reconstructor, which can be easily imple- easier to program with standard tools already optimised one together with its mented as a matrix-vector multiplication and languages. optimisation tools, but rather the people (MVM). For certain systems like EPICS factor: any coding effort, including the this measure can be prohibitively high, so Especially relevant here was the invited “hacking” part, requires people to do it this is where smart algorithms come into talk delivered by a worldwide expert in and perform long-term maintenance. It is play. the field of high performance computing, this latter aspect that will play a major author of FFTW (Fastest Fourier Trans- role in the decision process more than Smart algorithms can be divided into two form in the West) and Cilk (a computing the technical solution. broad categories: ones that use a sparse, language for multi-threaded parallel com- or sparsified, interaction matrix without puting), Matteo Frigo. One of the issues The other problem with an all-CPU strat- inverting it; and others that use a model clearly understood and mentioned also egy that the audience identified is the of the system, sometimes applying an in several talks is the need to develop a unpredictability of any CPU-based imple- interaction matrix to tune the model. In strategy for managing obsolescence, mentation: until code is instantiated on the former case the solution is found by since the main subject of the workshop is a given platform you will never know how using a conjugate gradient descent or a devoted to computer systems that will well it runs, making the cycle of design- variation of it. In the latter case it depends be operational for the first time in ten years on-paper-then-implement-on-silicon diffi- on which model is used. Several talks from now and will run for 10 to 20 years. cult to manage without proper proto in the algorithms session came from the Frigo explained how he designed FFTW typing. But it is clear that a system based Austrian Adaptive Optics group who are and Cilk in a fully portable way regardless on CPU with its inherent flexibility would contributing to ESO with in-depth research of the number of available cores, their be a powerful tool to test new strategies on novel reconstruction algorithms. Some cache or interconnections, without penal- and algorithms as well as powering a of their proposed algorithms have already ising performance, hints that can be laboratory system, where downtime is been tested on the laboratory bench and exploited in developing a CPU-based normally not the first issue to solve. even on sky (as reported at the work- system, in particular with the Phi. shop, [Bitenc]) and seem very promising. As a synthesis of all the presented tech- The portfolio of proposed algorithms The last technology family, standard nologies, the SPARTA team proposed a spans a broad range running from a sin- CPUs, was presented by several groups concept [Suarez] that encompasses gle conjugate AO (SCAO)/extreme AO who are pursuing implementations of many of the previous ideas in a flexible (XAO) system (the CuRE family of algo- small or medium-sized AO systems on an architecture originally presented at the rithms, [Rosensteiner] and [Shatokhina])

56 The Messenger 151 – March 2013 Figure 3. One of the Real Time Control for Adaptive Optics workshop sessions in the auditorium of ESO Headquarters.

real-time AO simulation system, similar to the end-to-end AO simulators used to predict system performance [Gratadour]. This will be desperately needed since the number of ELT-size AO benches and their availability will be extremely limited in the future and therefore the majority of the development and testing of the RTCs for the ELT AO-based instruments will be to multi-conjugate (MCAO)/laser tomo means of approximated methods. The done without a bench and only with the graphy (LTAO) AO (Kaczmarz and wave- feeling of the audience was that the con- aid of a simulation tool. Yet another chal- lets, [Ramlau] and [Yudytskiy]) with multi- vergence point has already passed, such lenge for the community. object AO in the works. that smart algorithms can be implemented into relatively small and cheap systems, Given the success of this second work- Further contributions from Lyon [Bechet] while traditional MVMs can now reach shop the community agreed to convene presented an optimisation of the already very large dimensions. It might now be a again in about 18 months for a third one. mature, at least in the simulation world, matter of choice: a relatively cheap Exact date and place will be published Frim algorithm, that has versions available system based on an approximated smart both on the workshop mini-site2 and on for SCAO and MCAO. This algorithm is algorithm or a more expensive, bigger the AO RTC collaborative web hub4. essentially a pre-conditioned conjugate system based on the well-known and Meanwhile all of the presentations given gradient (PCG) method, with an arrange- feature-rich MVM. Smart algorithms will at the workshop are available online2. ment that exploits the closed-loop nature certainly be more complex to implement of the process and thus reduces the than a plain MVM where extreme opti iterations of the PCG to only one, pushing misations can be obtained; therefore Acknowledgements the others outside the latency cycle, a smart algorithms might be best coupled The workshop was only possible thanks to the dedi- smart arrangement that is rather generic. with all-CPU systems or with CPU-based cation of the members of the Scientific Organising A contribution from TU-Delft [Verhaegen] accelerators, while highly optimised Committee (Alastair Basden, Dolores Bello, Corinne uses splines on triangular partitions to MVM-based algorithms can be better Boyer, Enrico Fedrigo [chair], Glenn Herriot, Arnaud reconstruct the wavefront in a highly par- served by GPU- or FPGA-based or accel- Sevin and Marcos Suarez [co-chair]), the Local Organising Committee (Samantha Milligan, Marcos allelisable architecture that, in a similar erated systems. Suarez, Enrico Fedrigo), the ESO IT Helpdesk, in way to the CuReD (a fast wavefront particular the video-conferencing team, and many re constructor), could address the E-ELT Amongst the major drivers that need others, who provided logistical support. We are par- planet-finder EPICS directly. Finally careful examination, the workshop identi- ticularly grateful to Samantha Milligan and her passion for detail, that everything in the organisation ran a method that only uses the images in fied on the one hand that the future RTC smoothly, and the very positive spirit of all attendees the science detector was proposed for AO will likely be a heterogeneous made all tasks very pleasant. I thank all the organis- [ Koriakoski], however it is still in an early computing environment [Dipper, Suarez] ers and participants. stage and suffers from several limitations. and, on the other, that software devel Overall, an impressive array of methods opment costs are going to be the impor- References and algorithms are now available to tant factor [Dipper]. Therefore the need replace traditional matrix-vector multipli- to share developments across instru- Kasper, M. & Beuzit, J. L. 2010, The Messenger, cation methods and the next step is to try ments arises. Amongst real systems, 140, 24 them out. SPARTA for the VLT has already achieved that [Suarez], serving 20 AO instruments Links of various sizes and characteristics. 1 Conclusions Moreover it features an almost complete The 2011 RTC for AO workshop pages: http://www.dur.ac.uk/cfai/ adaptiveoptics/rtc2011/ supervisor software that accounts for the 2 The 2012 RTC for AO workshop pages: http:// Two trends are developing and converg- majority of the coding effort. But other www.eso.org/sci/meetings/ 2012/RTCWorkshop. ing: a push to make the real-time con initiatives aim at achieving similar results. html 3 troller hardware faster and computation- SPARTA platform for AO RTC development for the VLT: http://www.eso.org/sci/facilities/develop/ao/ ally more powerful, and a push to reduce A “killer” feature of the future platforms tecno/sparta.html the required computational power by will be the capability to integrate a quasi 4 The AO RTC hub: http://aortc.ast.cam.ac.uk/

The Messenger 151 – March 2013 57 Astronomical News

Llullaillaco and Paranal’s Skyline

Reinhard Hanuschik1

1 ESO Gianluca Lombardi/ESO Gianluca The visibility of the volcano Llullaillaco from Paranal is discussed. That it can be seen at all depends on two circum- stances: a fortunate geometry and the superb quality of the atmosphere over the Atacama Desert, stretching over a baseline of 190 kilometres, much longer than in any astronomical observation.

If you have ever happened to visit Paranal you will have very likely recognised a majestic peak on the eastern horizon. This is Llullaillaco (pronounced You-ya-i-yaco, meaning “dirty lagoon” in Figure 1. Llullaillaco as seen from the VLT platform. metres). For orientation, the ruta 5 is also Ketschua), at 6739 metres above sea Close-up of a picture taken by Gianluca Lombardi on marked (red square). It is clear that we 19 December 2011. level, the third-highest peak in Chile, the have been lucky (or b enefit from careful seventh highest in the Andes, and argu planning) with the siting of the Paranal ably the highest active volcano in the Chilean–Argentine border. This is almost platform: if it had been blasted just a few world. The view from Paranal is shown in the entire width of Chile at this latitude. tens of metres lower, the view towards Figure 1. The last eruption of Llullaillaco the Llullaillaco summit would have been was recorded in 1877. It has beautiful lava If you take it for granted that one can vignetted by the nearby Sierra Vicuña flows extending both to the north and spot a 6700-metre peak from a distance Mackenna, as one can confirm by walk- south. During most of the year it appears of 190 kilometres, then it is interesting to ing down from the platform along the as snow-capped, although without gla- check the LOS profile (Figure 2, dotted blue road to the hairpin bend. The other ele- ciers: the snow limit in that part of the line) from Paranal (P) towards Llullaillaco ment of luck is that the LOS crosses the Andes is the highest in the world, at (L). There are two “critical” points: the Sierra just south of Cerro Armazones. about 6500 metres. Even in that part of nearby Sierra Vicuña Mackenna (A, the Andes you would have to travel 20 kilometres distant from Paranal, and In addition to the purely fortuitous terrain 265 kilometres to find a higher contour including Cerro Armazones), and the dis- morphology, there is another important (Tres Cruzes, 6749 metres). It is impres- tant Cordillera de Domeyko (B, 125 kilo- effect to take into account: the curvature sive even by Chilean standards, and of the Earth. With distance D from the dwarfs Europe’s highest mountain, Mt. reference point P, the deviation of the Blanc at 4810 metres. Figure 2. The line of sight (in blue), the terrain, and tangential plane from the (ideal) surface atmospheric layers, neglecting surface curvature curvature grows as D2/(2R), where R The first recorded ascent was in 19521, between Paranal (P) and Llullaillaco (L) . Intervening (6371 kilometres) is the mean Earth places are explained in the text. The terrain has been 2 but there were earlier visitors: the mum- taken from Google Earth. Distances are in kilome- radius . Figure 3 shows the LOS with cur- mies of three Inca children were discov- tres, elevation in metres. vature taken into account. Since the ered close to the summit in 1999, thus making Llullaillaco the highest archaeo- + logical site in the world. / Visibility ! There are several interesting aspects about Llullaillaco that are related to Paranal itself and its skies. First, as l Google Earth confirms, the Paranal– l l Llullaillaco line of sight (LOS) spans 190 kilometres, starting on the Paranal platform at an elevation of 2600 metres SLNROGDQHBBNMSNTQR +.2VHSGBTQU@STQD 2TQE@BD and ending at 6739 metres, right at the +HMDNERHFGS 3DQQ@HM

58 The Messenger 151 – March 2013 Light travelling through the atmosphere, no matter whether it is starlight or sun- / light scattered off Llullaillaco towards Paranal, is both absorbed and scattered. 3 We are discussing here much stronger $ % effects than are usual in astronomy: lines of sight towards the stars traverse the atmosphere roughly vertically, with a typi- l cal scale height of 8 kilometres, and the l first, and worst, 2.6 kilometres have l already been truncated by Paranal’s elevation. Here, we look through 190 kilo- 3DQQ@HMVHSŰ GBTQU@STQD SLNROGDQHŰ BBNMSNTQR metres of air, almost tangentially. What is 2TQE@BŰŰDVHSGBTQU@STQD +.2VHSŰ GBTQU@STQD the typical atmospheric elevation across that LOS? The blue LOS in Figure 2 stead- Figure 3. Same line of sight as Figure 2 but now The curvature effect is strongest for the ily increases from 2600 to 6700 metres, considering surface curvature of the Earth. The LOS most distant points, and much less so for but that needs to be corrected since the intersects with lower atmospheric layers than in Figure 2. This LOS with curvature is also sketched in the nearby and intermediate terrain. So, atmospheric layers follow the gravita- Figure 2 (red dotted line). surface curvature makes it much easier tional curvature (Figure 3). This is the red for the Sierra Vicuña Mackenna to mask LOS in Figure 3, repeated in Figure 2: all Llullaillaco, although it is only at the same points except the two end points cross curvature effect grows with D2 it affects altitude (2645 metres, curvature-cor- lower atmospheric layers than the uncor- Sierra Vicuña Mackenna by 30 metres rected) as Paranal itself. The curvature- rected LOS, with the maximum difference and the Cordillera de Domeyko, 125 kilo- corrected LOS requires 2763 metres at of about 600 metres in the middle, 95 kilo metres away, by 1.2 kilometres. At the that distance, giving a clearance of just metres from Paranal. Assuming constant distance of Llullaillaco (190 kilometres) 120 metres (point A in Figures 2 and 3), density in the atmosphere, the effective the surface curves down by an amazing which could indeed be called a near-miss average altitude in the uncorrected LOS 3.1 kilometres with respect to the tangen- given the geometrical dimensions of the would be 4700 metres, and 4200 metres tial plane! So that the summit has effec- problem. The much higher Cordillera de with curvature correction. A more realis- tively only an elevation of 3600 metres as Domeyko (3882 metres and 125 kilome- tic description of the atmosphere would seen from Paranal. tres distance away; point B in Figures 2 take into account its exponential struc- and 3) is less critical for the LOS, since it ture, with a much higher weighting given A careful analysis would also take atmos- is itself curvature-reduced by 1.2 kilo to the lowest layers. Since these are pheric refraction into account: objects metres, giving a comfortable clearance of close to Paranal, where curvature is in the far distance are effectively lifted up more than 800 metres. smallest, we can keep things simple and and the effect of curvature is thus re ignore the curvature-induced correction duced. This is usually accounted for by in the following. choosing a 10% higher value for R in the Transparency above formula, lifting Llullaillaco by the The LOS towards Llullaillaco is dominated same 10% to 4.1 kilometres. This effect is With the geometry sorted out, now we by atmospheric layers well above the neglected in the following discussion. need to look at sky transparency: how is atmospheric boundary layer, sometimes it possible to look through the atmos- also called the inversion layer. Most of the phere along a 190-kilometre baseline and atmospheric dust, aerosols and humidity Figure 4. Llullaillaco in winter, displaying a spectacu- larly rich contrast and wealth of details (taken on still retain excellent contrast (as evident are trapped below that boundary zone. 14 July 2012 by Dimitri Gadotti). from Figure 4)? Astronomical observations with Paranal Dimitri Gadotti/ESO

The Messenger 151 – March 2013 59 Astronomical News Hanuschik R., Llullaillaco and Paranal’s Skyline

instruments measure the quality of the atmosphere by the extinction, the fraction of light being absorbed or scattered by the atmosphere. In the V passband (visual, centred around 550 nm) the extinction towards the zenith is about 0.12 mag, or about 12% on a good Paranal night, occurring in the roughly 4–5 kilometre-long column of air effectively contributing above the observatory. Most of the extinction is caused by scattering, whereby the wavelength of the photon is preserved, but its directional information is lost, degrading the contrast. (Light is scattered out of the LOS, Figure 5. Summer view of Llullaillaco taken by the but light from other sources is also ran- author, from Cerro Armazones, in November 2009. domly scattered into the LOS. Blue day- light is an example of the scattering of blue sunlight, completely disassociated Figure 6. Satellite pic- from its original direction.) ture of Llullaillaco, ren- dered in 3D by the author using the infor- In clear skies, mountains turn blue in the mation available from distance, just like the open sky, and even- Google Earth (view tually can’t be distinguished from the sky. towards the east into Argentina, north is left, So what do you need to see a target at with Paranal behind the 190 kilometres, apart from visibility? Con- viewer). This close-up trast! Llullaillaco is very cooperative with view is from almost the visible snow fields on dark lava rocks same direction as from Paranal. throughout the year, and in particular during the winter months (Figures 4 and 7).

Still, with 12% contrast loss over 5 kilometres, less than 1% of “quality” light 3500–4000 metres, the Atacama atmos- famous aerial photo (Figure 7), helps a (with preserved directional and colour phere does not contribute significantly lot when trying to spot the volcano information) would remain over a 190-kilo to the extinction, and the larger part of Socompa. This mountain to the north of metre baseline, while a rule-of-thumb the LOS towards Llullaillaco suffers virtu- Llullaillaco is also visible from Cerro suggests that a minimum of 2% contrast ally no extinction. Armazones. Possibly Cerro Pular is also is required3. Looking at Figure 4, the visible (6230 metres, 244 kilometres), contrast of Llullaillaco must be much bet- The very long baseline must also be but this is unconfirmed. None of them ter than 2%: one can distinguish crisp essentially free of dust; a significant offers the same spectacular view as Llull- white and dark bands that can readily be assertion given all the open-pit mining aillaco since they are lower in altitude, identified with features visible on satellite and industrial activity taking place in further away, and have few if any snow imagery presented by Google Earth (Fig- the Atacama Desert. The main dust fields. ure 6). Visibility of this quality is not a rare source in that direction, the Escondida exception, as confirmed by quotes from copper mine (currently the largest on Finally, there is another interesting frequent Paranal observers (Gadotti, Earth), is comfortably north of the LOS to question: could one spot Paranal from 2013; priv. comm.) and by other pictures, Llullailliaco. Llullaillaco? The issue is contrast, again. like the one by Gerd Hüdepohl (Figure 7). Seen from Cerro Armazones, Paranal Are there other peaks visible from P aranal, is mainly visible by its structures, and the The apparent contradiction between constituting a true “skyline”? There are contrast is poor even at short distances, these photographs with their amazing some other candidates in the “summit at least for most of the day. Spotting contrast, and the estimates from astro- 6000” club, like Socompa (6050 metres Paranal from the summit would require nomical observations can likely be at 222 kilometres); Lastarria (5700 metres, climbing to at least 5500 metres (roughly explained by assuming that most of the 202 kilometres; not quite 6000 metres, the altitude of the lowest part of Llullaillaco atmospheric extinction actually hap- but close); or Pular (6230 metres, 244 kilo visible from Paranal). The best contrast pens even closer to the ground than metres). However, all of these are hidden could be expected in the morning, so you assumed above, in the densest parts of behind the Sierra Vicuña Mackenna as would need to stay overnight, at tempera- the atmosphere just above the Obser seen from Paranal. But moving just a bit tures reported by mountaineers to be as vatory. It seems that beyond roughly higher, as Gerd H üdepohl did for his low as –20 or –30°C. Just before morning

60 The Messenger 151 – March 2013 Astronomical News

Figure 7. Winter view of coffee you could probably spot the Llullaillaco, taken by first rays of the Sun reflected off the silver Gerd Hüdepohl in July 2002 from an aeroplane, domes in a spectacular flash, as in i.e., with a slightly dif Gianluca Lombardi’s picture of Paranal

Gerd Hüdepohl/ESO Gerd ferent LOS than in the taken from Cerro Armazones4. Probably other pictures, but from the three Inca children could tell, as a similar distance. The volcano Socompa is they might have enjoyed this view every the peak close to the morning for a few years. Not for too long lefthand edge. though, since their mummies were discovered in 1999 and taken to a museum in Salta/Argentina.

Links

1 Cerro Llullaillaco: http://en.wikipedia.org/wiki/Llullaillaco 2 Mean radius of the Earth: http://en.wikipedia.org/wiki/Horizon 3 Contrast of distant objects: http://en.wikipedia.org/wiki/Visibility 4 View of Paranal from Armazones: http://www.eso.org/public/images/potw1205a/

Hännes Heyer Retires

Lars Lindberg Christensen1 Figure 1. Among the gifts received by Hännes Heyer at his farewell reception on 6 Decem- 1 ESO ber 2012 was a mounted print of one of his photographs signed by his colleagues. He is shown Hännes, or Hans Hermann, Heyer was at holding this trophy aloft. ESO for 25 years and experienced the remarkable coincidence of being hon- oured for both his retirement and celebrat- ing his 25th anniversary at ESO on the same day. On the morning of 6 December 2012 the Director General hosted a small ceremony for Hännes as well as two other staff members, Hélène Neuville and Enzo Brunetto, and in the afternoon Hännes was at the centre of a reception in the Council Room in Garching (see Figure 1).

There is hardly anyone at ESO who does Information and Photographic Service exciting time of the 1985–86 Halley appa- not know Hännes. He has played an (IPS, reflecting the origins of key staff in rition. At that time, science communica- important role in taking and curating our the former ESO Sky Atlas Laboratory). tion as a profession hardly existed and a photographs since the days of the ESO The IPS was created in 1986, during the fully developed conceptual framework

The Messenger 151 – March 2013 61 Astronomical News

for such activities had yet to materialise. In that sense, at least in Europe, ESO certainly found itself among the pioneers in the field. Hännes, hired as a photographer and one of the first people in this new progressive department in 1987, was one of those pioneers.

With growing experience came the reali- sation that information is a commodity that must be managed, and the department changed its name in the early 1990s to the ESO Education and Public Rela- tions Department (EPR), and naturally Hännes moved into the new era. The new name revealed the strategic choice that ESO had made in engaging in science education activities. In 2005, the department underwent a restructuring, following the recommendations of the 2004 ESO Visiting Committee as far as possible. The name change to the Public Affairs Depart- ment (PAD) signified a step towards addressing political decision-makers and Figure 2. One of Hännes' early photographic images Hännes has really left his mark on ESO: administrators. After a review in 2008, of which he was proud — moonrise over the Andes when you walk around the buildings from La Silla. PAD became the education and Public in Garching and Chile, many of the photo Outreach Department (ePOD) as it is graphs you’ll see on the walls are from known today. As our photographer, Claus Madsen on many of the photo- him. Also many of the photographs that Hännes has documented many of the key graphs in his book The Jewel on the have featured in The Messenger were moments in ESO’s history during his time Mountaintop. Historical photographs are taken by Hännes and many ESO staff, here, and he has an almost encyclopae- an area where Hännes made an impor- visitors and committee members have dic knowledge of the events, people, and tant and long-lasting impact: in the lead- been photographed by him, whether images over the decades. up to the anniversary a significant effort at meetings, in group photos, or even for was made to digitise the most important staff ID cards. As such, he played an important role in photographs in ESO’s historical photo our celebrations of ESO’s 50th Anniver- archive to create a legacy that will stand A big thank you to Hännes for all he has sary in 2012, and he worked closely with for many years. put into ESO over the past 25 years!

New Implementation of the ESO Data Access Policy

As of ESO Observing Period 91, the ESO allows associated calibrations and ancil- This new implementation applies to all Science Archive Facility is the sole lary files to be associated to raw science observations belonging to Observing access point for data obtained with ESO files for further processing. Period 91 and onwards, as well as data telescopes. This includes access to pro- from earlier Observing Periods which prietary data for both Visitor and Service As of 1 April 2013, the proprietary period were carried over to Period 91. Mode runs. for all science and acquisition files will run from the moment the file can be accessed Typically, the files become available from and downloaded from the Archive. This Links the Science Archive Facility1 within a few means that the “proprietary period” will 1 Science Archive Facility: http://archive.eso.org hours of the time of observation. The begin on that date. No PI or PI delegate Archive Calibration Selector service action will affect the proprietary period.

62 The Messenger 151 – March 2013 Astronomical News

Fellows at ESO

Luca Cortese

Becoming an astronomer was definitely not my childhood dream. Until secondary school, I wanted to become an architect and design something as amazing as the Sydney Opera House. I suspect that this was mainly driven by my early great passion for LEGO.

I was born and grew up in Milano (Italy) and only started to develop a deep interest in astrophysics during high school. A significant influence on this passion came from my father’s fascination with astronomy and, probably, also from the fact the walls of my parents’ house Luca Cortese have always been filled with maps of the night sky and images of Jupiter’s moons taken by Voyager 2. Thus, when I started staying in Milan, where I started a PhD to the radio regime, as I carried out 21 cm my undergraduate degree in physics under Peppo’s supervision at the end of observations of nearby galaxies to study at Milan University in the autumn of 1997, 2002. Looking back at those days, I am their atomic gas reservoir. This gave my goal was to become a professional very glad with how things went. I was me the opportunity to use the Arecibo astronomer. However, I had to wait until lucky enough to win a grant that allowed radio telescope in Puerto Rico, the larg- winter 2001 to start getting my hands me to carry out half of my thesis work in est single-dish telescope in the world, dirty with what, since then, has become France, at the Laboratoire d’Astrophysique and definitely one of the most amazing my everyday job. de Marseille, under the supervision of astronomical facilities I have had the privi- Alessandro Boselli. This gave me the op lege to use. Then, starting from 2008, As part of Peppo Gavazzi’s course of portunity to become heavily involved I changed wavelength domain again, laboratory astrophysics, we went to in the exploitation of the data obtained by becoming deeply involved in the planning the Loiano Observatory (in the Italian the GALEX mission, a NASA space tele- and exploitation of far-infrared and sub- Apennines) to observe galaxies in nearby scope which carried out the first survey millimetre surveys of nearby galaxies clusters. At least this was the original of the entire sky at ultraviolet wave- carried out with ESA Herschel Space plan. Out of the ten nights we had, eight lengths. So, I spent the three years of my Observatory. Herschel observations are were lost due to bad weather and we PhD studying the effects of the environ- crucial to gain information on the role were almost ready to pack and go back ment on the star formation and dust played by the dust on the star formation home when the sky finally started to ex tinction properties of cluster galaxies. cycle of nearby galaxies. clear. Unfortunately, it had snowed a lot It was during this time that I had my first during the previous days and the dome experience at ESO, observing at the In the summer of 2010, I crossed the was covered in snow. Thus, we ended up 3.6-metre telescope in La Silla. This was Channel again to start a Fellowship spending the entire afternoon manually a very different experience compared at ESO in Garching. Working at ESO has clearing the dome and the roof of the to my previous observing trips: the sys- allowed me to experience directly how building, just to be able to have our first tem performance was very smooth, the Atacama Large Millimeter/submillime- hands-on experience at the telescope. which made the observations almost too ter Array (ALMA) works. The opportunity The following night turned out to be an easy (when it comes to observations, to help carry out Cycle 0 observations amazing experience, and I realised then “boring is good”!). at the ALMA site, and experiencing how that observational astronomy was exactly this amazing facility works, is definitely what I wanted to do. For the final stage With a PhD degree in the bag, on a rainy the highlight of my time at ESO. More of my undergraduate degree, I decided to day in January 2006 I filled up my car over, by getting involved in ALMA, I have undertake a Master’s thesis with Peppo with all my stuff and drove the 1500 kilo- been able to gain familiarity with milli on the analysis of Hα images of galax- metres between Milan and Wales to start metre interferometric observations. This ies in nearby clusters. The experience a postdoctoral position at Cardiff Univer- is one of the most amazing parts of this was so rewarding that I was even more sity, in the group led by Jonathan Davies. job. In the last ten years I have been able certain that I had taken the right path. Although my initial contract was for just to keep studying the same galaxies, but one year and half, I spent four and half the advent of new facilities has made it My initial plan was to leave Italy and carry amazing years in Wales. Working at possible to look at them from very differ- out a PhD abroad. However, finding a Cardiff has been a great experience both ent points of view, thus always yielding PhD place turned out to be more compli- professionally and personally. At first, my new insights into how they formed and cated than anticipated and I ended up investigations shifted from the ultraviolet evolved.

The Messenger 151 – March 2013 63 Astronomical News

ESO is definitely a unique place at which to carry out a postdoctoral fellowship. It provides you with deep insights into how modern observatories work, something that it is impossible to imagine while working at other universities or research institutes.

Sadly, my experience at ESO is now coming to an end. In just a few months I will leave Europe to move to Australia, opening another, certainly exciting, chap- ter of my job as an astronomer.

Grant Tremblay

When I was nine years old, I was the world’s worst paleontologist. Based on Grant Tremblay embarrassingly weak evidence, I was convinced that there was a dinosaur bur- ied in the field behind my house in Maine, Space Telescope) and the other half in vates buoyant bubbles large enough to USA. I asked my father to inform the local Rochester, I had dreamed of going to encompass 500 Milky Way galaxies. And science museum of my impending find, Europe for my first postdoc. Being from I thought dinosaurs were big! and I launched a carefully planned and the US, an ESO Fellowship felt so out well-researched expedition to excavate it. of reach. Yet in addition to building the I don’t know where I’ll end up next, but When I mistook the white root of a sap- world’s greatest telescopes, one of I’ll always be grateful for my years at ling for the neck bone of a Dilophosaurus, ESO’s most important gifts to the world is ESO. A year after my failed dinosaur hunt, I was overcome with the sort of elation its perfect illustration of international I first saw the rings of Saturn through that could only herald a future astrono- cooperation toward a common goal, and my tiny toy telescope, and it started me mer’s first spectacular failure in science. of human collaboration that is blind to on the path towards becoming an astron- borders and flags. ESO welcomed me, omer. Twenty years later, thanks to ESO, I may have been disappointed when I and I now live in both Germany and Chile, I find myself writing these words in the realised my dinosaur was actually a and have an incredible group of friends Paranal Observatory control room, using mound of dirt and shrubbery, but the and collaborators from no less than a telescope with 12 000 times greater experience was a perfect illustration 27 different countries. In addition to my light-collecting area. I still haven’t found of why I love science. Amid the collapse Fellowship in Garching, my ESO duties any dinosaurs, but I guess I haven’t of my hypothesis, I learned the differ- are performed as an astronomer in the stopped searching. ence between bones and fossils, discov- Paranal Observatory Science Operations ered that plant roots could be bright team, supporting UT2/Kueyen on the white, and realised, after some follow-up Very Large Telescope. Every night at the research, that a field in Maine is not telescope, I feel like that kid in the field in the likeliest place to find giant ancient Maine. reptiles. Most importantly, I learned that human beings advance our understand- My own research uses data from the VLT, ing of Nature not by becoming more as well as the Hubble Space Telescope, right, but by slowly becoming less wrong. Chandra X-ray Observatory, Herschel Today, I am grateful for the privilege and now ALMA to study the black-hole- of working in a field where getting things powered outflows of nearby radio galax- wrong is the most important part of even- ies. They are amongst the largest and tually getting it right. most powerful objects in the Universe, and many of them are embedded in This is why I feel so lucky to be at ESO. megaparsec-scale halos of ultra-hot pri- After doing half of my PhD research mordial gas. The mechanical feedback at the Space Telescope Science Institute associated with the propagation of these (the operational heart of the Hubble outflows amid their atmospheres exca-

64 The Messenger 151 – March 2013 Astronomical News

ESO

European Organisation for Astronomical Research in the Southern Hemisphere

ESO Studentship Programme

The research studentship programme of the European Southern The Outline of the Terms of Service for Students (http://www.eso.org/ Observatory provides an outstanding opportunity for PhD students public/employment/student.html) provides some additional details on to experience the exciting scientific environment at one of the world’s the employment conditions and benefits. leading observatories for a period of up to two years. If you are interested in enhancing your PhD experience through an ESO is the foremost intergovernmental astronomy organisation in extended stay at ESO please apply online at https://jobs.eso.org/. Europe. Its approximately 110 staff astronomers, 40 Fellows and Reference letters to support your application should be sent to 50 PhD students conduct frontline research in fields ranging from [email protected] for Garching and [email protected] for Chile. exoplanets to cosmology, offering one of the most vibrant and stimulating scientific settings anywhere in the world. Please include the following documents in your application: – a Curriculum Vitae (including a list of publications, if any); ESO’s studentship positions are open to students enrolled in a PhD – copies of your university transcript and certificate(s) or diploma(s); programme in astronomy or related fields. Students accepted into the – a summary of your master’s thesis project (if applicable) and ongo- programme work on their doctoral project under the formal supervi- ing projects, indicating the title and the supervisor (maximum half a sion of their home university, but they come to ESO to work and study page); under the co-supervision of an ESO staff astronomer, normally for a – an outline of the proposed PhD project highlighting the advantages period of between one and two years. Studentships may be hosted of coming to ESO (recommended one page, maximum two); either at ESO’s Headquarters in Garching (Germany) or at ESO’s – two letters of reference, one from the home institute supervisor and offices in Santiago (Chile), where two additional positions per year are one from the ESO local supervisor; provided for students enrolled in South American universities. – a letter from the home institute that i) guarantees the financial support for the remaining PhD period after the termination of the Applicants and their home institute supervisors should agree upon ESO studentship, ii) indicates whether the requirements to obtain and coordinate their research project jointly with their prospective the PhD degree at the home institute have already been fulfilled. ESO supervisor. For this purpose the ESO supervisor should be contacted well in advance of the application deadline (15 June 2013). All documents should be typed in English (but no translation is A list of potential ESO supervisors and their research interests can required for the certificates and diplomas). be found at http://www.eso.org/sci/activities/personnel.html. A list of PhD projects currently being offered by ESO staff is available at Closing date for applications is 15 June 2013, and review of the http://www.eso.org/sci/activities/thesis-topics.html. application documents (including the recommendation letters) will begin immediately. Incomplete applications will not be considered. It is highly recommended that applicants plan to start their PhD studies at their home institute before continuing to develop their Candidates will be notified of the results of the selection process research projects at ESO. during July–August 2013. Studentships typically begin between August of the current year and March of the following year. ESO Chile students have the opportunity to visit the observatories and to get involved in small technical projects aimed at giving insights For further information please contact Christina Stoffer into the observatory operations and instrumentation. Such involve- ([email protected]). ment is also strongly encouraged for Garching students. In addition, students in Garching may attend and benefit from the series of Although recruitment preference will be given to nationals of ESO lectures delivered in the framework of the International Max Planck Member States (members are: Austria, Belgium, Brazil, the Czech Research School on Astrophysics. Republic, Denmark, Finland, France, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and United Kingdom) no Students who are already enrolled in a PhD programme in the nationality is in principle excluded. Munich area (e.g., at the International Max Planck Research School on Astrophysics or a Munich University) and who wish to apply for an The post is equally open to suitably qualified female and male ESO studentship in Garching, should provide a compelling justifica- applicants. tion for their application.

The Messenger 151 – March 2013 65 Astronomical News

Announcement of the ESO Workshop Deconstructing Galaxies: Structure and Morphology in the Era of Large Surveys

18–22 November 2013, ESO Vitacura, Santiago, Chile

The study of the structure and morphol- has grown considerably in recent years. ogy of galaxies is one of the major tools It is thus important to address the astronomers have to address how gal strengths and limitations of the different axies form and evolve. Recent progress techniques, particularly with the expec in the field has boosted our understand- tation that automated procedures ing of the properties of different structural designed to handle large surveys may components in nearby galaxies, as well prevail in the future. as in galaxies at intermediate redshifts (z ~ 1–2). Yet the link between structural This conference will bring together over properties, kinematics, stellar population 100 observers and theorists, and it is content and the complex physics in intended to be highly participative with volved in the formation and evolution of substantial time devoted to discussions. galaxies is a much more challenging It should set the basis for the study of step. One of the major goals of this con- galaxy structure and morphology in the ference is to address this connection, next decade. by questioning, for instance, what the structure of galaxies tells us about their Pre-registration is open until 1 April. formation and evolution, and how observations can help constrain models. Details are available at: http://www.eso.org/sci/meetings/2013/ In addition, the complexity of methods morph2013.html used to obtain structural measures or by email to: [email protected].

Announcement of the ESA/ESO Workshop SCIENCE OPERATIONS 2013: Working Together in Support of Science

10–13 September 2013, ESAC, Madrid, Spain

The objective of SCIOPS 2013 is to pre- ... throughout all project phases from ini- sent and discuss the various approaches tial concepts to legacy products. to science operations in spacecraft missions and ground-based facilities for Details are available at: astronomy and Solar System science. http://www.sciops.esa.int/sciops2013 or by email to: [email protected]. The meeting is intended to: – Compare and improve our processes The abstract deadline is 1 May 2013 and approaches and registration will close on 15 July – Foster innovations 2013. – Enable a more efficient use of our resources – Establish and intensify collaborations

via a focus on: – Community support and services – Science and instrument planning – Instrument handling and calibration – Science data processing – Science data archiving and product generation – Science operations organisation and management

66 The Messenger 151 – March 2013 Astronomical News

Announcement of the Workshop 400 years of Stellar Rotation

17–22 November 2013, Natal, Brazil

In 1613 Galileo Galilei reported in the fundamental parameter can also provide l’Istoria e dimostrazioni intorno alle important constraints for models of stellar macchie solari e loro accidenti the evi- evolution, as well as important informa- dence of solar spots and the inter tion on the presence of external rotational pretation of their motion as due to solar brakes, tidal interactions in binary sys- rotation. After 400 years we are able tems and on the mechanisms controlling to quantify, thanks to extremely fine stellar activity. Rotation also plays a experiments like SOHO, details of the primary role in stellar chemical evolution internal and surface rotation of the and it reflects the complex interaction Sun, and to measure, thanks to precise between stars and the circumstellar/ photometry obtained with the Kepler proto planetary disc in the pre-main and COROT satellites, rotation periods sequence phase. for large numbers of stars. In addition, projected rotational velocities (Vsini) are To celebrate the 400 years of the public now available for thousands of these announcement of the Sun’s rotation by stars, thanks to ground-based high reso- Galileo Galilei, the workshop, 400 Years lution spectroscopy. These data offer the of Stellar Rotation, co-sponsored by the unique possibility to study in detail the European Southern Observatory and behaviour of the rotation of the Sun the International Institute of Physics of over time, as well as the evolutionary Natal, will be held in Natal, Brazil. behaviour of stellar rotation all along the Hertzsprung–Russell diagram. Additional information can be found at the workshop website: Stellar rotation is not only a key ingredient http://www.dfte.ufrn.br/400rotation/. to understanding solar and stellar angular momentum evolution properly. This Registration is open until 1 June 2013.

Personnel Movements

Arrivals (1 January–31 March 2012) Departures (1 January–31 March 2012)

Europe Europe Barbosa, Carlos Eduardo (BR) Student Allouche, Fatme (RL) Instrumentation Engineer De Pascale, Marco (I) Student Alvarez Candal, Alvaro (RA) Fellow Gall, Elisabeth (D) Student Drouart, Guillaume (F) Student Jochen, Haucke (D) Head of Software Engineering Iribarrem, Alvaro (BR) Student Riedel, Mario (D) Administrative Clerk Lakicevic, Masha (SRB) Student Zocchi, Alice (I) Student Longmore, Steven (GB) Fellow Märcker, Matthias (D) Fellow Rushton, Anthony (GB) Fellow Smolcic, Vernesa (HR) Fellow Zilker-Kramer, Irmtraud (D) Paid Associate

Chile Chile González, Edouard (RCH) Telescope Instruments Operator Araya, Ernesto (RCH) Optical Technician Pallanca, Laurent (F) Instrumentation Engineer Barria, Daniela (RCH) Student Razmilic, Jasna (RCH) Executive Assistant Bhatia, Ravinder (GB) Project System Engineer Sippel, Anna (D) Student de Graauw, Mattheus Thijs (NL) ALMA Director Smith, Gerardo (RCH) Electronics Technician Lieder, Stefan (D) Student Riffo, Lidia (RCH) Secretary Tyndall, Amy (GB) Student West, Michael (USA) Head of Science Vitacura

The Messenger 151 – March 2013 67 Annual Index 2012 (Nos. 147–150)

Subject Index A Method to Deal with the Fringe-like Pattern in Astronomical Science VIMOS-IFU Data; Lagerholm, C.; Kuntschner, H.; Cappellari, M.; Krajnovíc, D.; McDermid, R.; Determining the Cepheid Period–Luminosity ESO 50th Anniversary Rejkuba, M.; 148, 17 Relation Using Distances to Individual Cepheids Astronomical Spectrograph Calibration at the from the Near-infrared Surface Brightness A Milestone for The Messenger in ESO’s 50th Exo-Earth Detection Limit; Lo Curto, G.; Pasquini, Method; Storm, J.; Gieren, W.; Fouqué, P.; Anniversary Year; de Zeeuw, T.; 150, 2 L.; Manescau, A.; Holzwarth, R.; Steinmetz, T.; Barnes, T. G.; Granzer, T.; Nardetto, N.; Reflections from Past Directors General; Woltjer, L.; Wilken, T.; Probst, R.; Udem, T.; Hänsch, T. W.; Pietrzyński, G.; Queloz, D.; Soszyński, I.; van der Laan, H.; Giacconi, R.; Cesarsky, C.; González Hernández, J.; Esposito, M.; Rebolo, R.; Strassmeier, K. G.; Weber, M.; 147, 14 150, 3 Canto Martins, B.; Renan de Medeiros, J.; 149, 2 Resolved Stellar Populations with MAD: Preparing ESO 50th Anniversary Gala Dinner; Sirey, R.; 150, 7 ESO VISTA Public Surveys — A Status Overview; for the Era of Extremely Large Telescopes; Arnaboldi, M.; Rejkuba, M.; Retzlaff, J.; Delmotte, Fiorentino, G.; Tolstoy, E.; Diolaiti, E.; Valenti, E.; N.; Hanuschik, R.; Hilker, M.; Hümmel, W.; Cignoni, M.; Mackey, A. D.; 147, 17 Telescopes and Instrumentation Hussain, G.; Ivanov, V.; Micol, A.; Neeser, M.; The Search for Intermediate-mass Black Holes in Petr-Gotzens, M.; Szeifert, T.; Comeron, F.; Globular Clusters; Lützgendorf, N.; Kissler-Patig, High-speed Bandwidth between Europe and Primas, F.; Romaniello, M.; 149, 7 M.; de Zeeuw, T.; Baumgardt, H.; Feldmeier, A.; Paranal: EVALSO Demonstration Activities and On the Photometric Calibration of FORS2 and the Gebhardt, K.; Jalali, B.; Neumayer, N.; Noyola, E.; Integration into Operations; Comerón, F.; Sloan Digital Sky Survey; Bramich, D.; Moehler, S.; 147, 21 Emerson, J.; Kuijken, K.; Zampieri, S.; Wright, A.; Coccato, L.; Freudling, W.; Garcia-Dabó, C. E.; The Gaia-ESO Public Spectroscopic Survey; Filippi, G.; 147, 2 Møller, P.; Saviane, I.; 149, 12 Gilmore, G.; Randich, S.; Asplund, M.; Binney, J.; News of the MUSE; Bacon, R.; Accardo, M.; Adjali, Provisional Acceptance of KMOS; Ramsay, S.; Bonifacio, P.; Drew, J.; Feltzing, S.; Ferguson, A.; L.; Anwand, H.; Bauer, S.-M.; Blaizot, J.; Boudon, 149, 16 Jeffries, R.; Micela, G.; Negueruela, I.; Prusti, T.; D.; Brinchmann, J.; Brotons, L.; Caillier, P.; Gearing up the SPHERE; Kasper, M.; Beuzit, J.-L.; Rix, H.-W.; Vallenari, A.; Alfaro, E.; Allende-Prieto, Capoani, L.; Carollo, M.; Comin, M.; Contini, T.; Feldt, M.; Dohlen, K.; Mouillet, D.; Puget, P.; Wildi, C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Braga- Cumani, C.; Daguisé, E.; Deiries, S.; Delabre, B.; F.; Abe, L.; Baruffolo, A.; Baudoz, P.; Bazzon, A.; glia, A.; Flaccomio, E.; François, P.; Irwin, M.; Dreizler, S.; Dubois, J.-P.; Dupieux, M.; Dupuy, C.; Boccaletti, A.; Brast, R.; Buey, T.; Chesneau, O.; Koposov, S.; Korn, A.; Lanzafame, A.; Pancino, E.; Emsellem, E.; Fleischmann, A.; François, M.; Claudi, R.; Costille, A.; Delboulbé, A.; Desidera, Paunzen, E.; Recio-Blanco, A.; Sacco, G.; Smil- Gallou, G.; Gharsa, T.; Girard, N.; Glindemann, A.; S.; Dominik, C.; Dorn, R.; Downing, M.; Feautrier, janic, R.; Van Eck, S.; Walton, N.; 147, 25 Guiderdoni, B.; Hahn, T.; Hansali, G.; Hofmann, P.; Fedrigo, E.; Fusco, T.; Girard, J.; Giro, E.; Teenage Galaxies; Contini, T.; Epinat, B.; Vergani, D.; D.; Jarno, A.; Kelz, A.; Kiekebusch, M.; Knudstrup, Gluck, L.; Gonte, F.; Gojak, D.; Gratton, R.; Queyrel, J.; Tasca, L.; Amram, P.; Garilli, B.; J.; Koehler, C.; Kollatschny, W.; Kosmalski, J.; Henning, T.; Hubin, N.; Lagrange, A.-M.; Langlois, Kissler-Patig, M.; Le Fèvre, O.; Moultaka, J.; Laurent, F.; Le Floch, M.; Lilly, S.; Lizon à M.; Mignant, D.L.; Lizon, J.-L.; Lilley, P.; Madec, F.; Paioro, L.; Tresse, L.; Lopez-Sanjuan, C.; Perez- L’Allemand, J.-L.; Loupias, M.; Manescau, A.; Magnard, Y.; Martinez, P.; Mawet, D.; Mesa, D.; Montero, E.; Perret, V.; Bournaud, F.; Divoy, C.; Monstein, C.; Nicklas, H.; Niemeyer, J.; Olaya, Möller-Nilsson, O.; Moulin, T.; Moutou, C.; O’Neal, 147, 32 J.-C.; Palsa, R.; Parès, L.; Pasquini, L.; Pécontal- J.; Pavlov, A.; Perret, D.; Petit, C.; Popovic, D.; The Chemistry and Magnetism of Young and Old Rousset, A.; Pello, R.; Petit, C.; Piqueras, L.; Pragt, J.; Rabou, P.; Rochat, S.; Roelfsema, R.; Intermediate-mass Stars Observed with CRIRES; Popow, E.; Reiss, R.; Remillieux, A.; Renault, E.; Salasnich, B.; Sauvage, J.-F.; Schmid, H. M.; Hubrig, S.; Cowley, C. R.; Castelli, F.; González, J. Rhode, P.; Richard, J.; Roth, J.; Rupprecht, G.; Schuhler, N.; Sevin, A.; Siebenmorgen, R.; F.; Wolff, B.; Elkin, V. G.; Mathys, G.; Schöller, M.; Schaye, J.; Slezak, E.; Soucail, G.; Steinmetz, M.; Soenke, C.; Stadler, E.; Suarez, M.; Turatto, M.; 148, 21 Streicher, O.; Stuik, R.; Valentin, H.; Vernet, J.; Udry, S.; Vigan, A.; Zins, G.; 149, 17 POPIPlaN: A Deep Morphological Catalogue of Weilbacher, P.; Wisotzki, L.; Yerle, N.; Zins, G.; Growth of Observing Programmes at ESO; Patat, F.; Newly Discovered Southern Planetary Nebulae; 147, 4 Hussain, G.; 150, 17 Boffin, H. M. J.; Jones, D.; Beletsky, Y.; van den APEX–SZ: The Atacama Pathfinder EXperiment Report of the ESO OPC Working Group; Brinks, E.; Ancker, M.; Smoker, J.; Gadotti, D.; Saviane, I.; Sunyaev–Zel’dovich Instrument; Schwan, D.; Leibundgut, B.; Mathys, G.; 150, 20 Moehler, S.; Ivanov, V. D.; Schmidtobreick, L.; Kneissl, R.; Ade, P.; Basu, K.; Bender, A.; Bertoldi, Holographic Imaging: A Versatile Tool for High 148, 25 F.; Böhringer, H.; Cho, H.-M.; Chon, G.; Clarke, J.; Angular Resolution Imaging; Schödel, R.; Girard, 3D Visualisation of Integral Field Spectrometer Data; Dobbs, M.; Ferrusca, D.; Flanigan, D.; Halverson, J. H.; 150, 26 Campbell, R.; Kjær, K.; Amico, P.; 148, 28 N.; Holzapfel, W.; Horellou, C.; Johansson, D.; The ESO 3D Visualisation Tool; Kuntschner, H.; First published ALMA Early Science Cycle 0 Result Johnson, B.; Kennedy, J.; Kermish, Z.; Klein, M.; Kümmel, M.; Westmoquette, M.; Ballester, P.; — Mapping of the Fomalhaut Debris Disc; Walsh, Lanting, T.; Lee, A.; Lueker, M.; Mehl, J.; Menten, Pasquini, L.; 150, 30 J.; Testi, L.; 148, 32 K.; Muders, D.; Pacaud, F.; Plagge, T.; Reichardt, X-shooter Spectroscopy of Massive Stars in the C.; Richards, P.; Schaaf, R.; Schilke, P.; Sommer, Local Group and Beyond; Sana, H.; de Koter, A.; M.; Spieler, H.; Tucker, C.; Weiss, A.; Westbrook, Garcia, M.; Hartoog, O.; Kaper, L.; Tramper, F.; B.; Zahn, O.; 147, 7 Herrero, A.; Castro, N.; 148, 33 Recent Progress Towards the European Extremely New Surprises in Old Stellar Clusters; Saviane, I.; Large Telescope (E-ELT); McPherson, A.; Held, E. V.; Da Costa, G. S.; Sommariva, V.; Gilmozzi, R.; Spyromilio, J.; Kissler-Patig, M.; Gullieuszik, M.; Barbuy, B.; Ortolani, S.; 149, 23 Ramsay, S.; 148, 2 Stellar Populations of Bulges in Galaxies with Low Monitoring Atmospheric Water Vapour over Paranal Surface-brightness Discs; Morelli, L.; Corsini, E. to Optimise VISIR Science Operations; Kerber, F.; M.; Pizzella, A.; Dalla Bontà, E.; Coccato, L.; Rose, T.; van den Ancker, M.; Querel, R. R.; 148, 9 Méndez-Abreu, J.; Cesetti, M.; 149, 28 PILMOS: Pre-Image-Less Multi-Object Spectros- On the Inside of Massive Galaxies: The Sloan Lens copy for VIMOS; Bristow, P.; Baksai, P.; Balestra, ACS Survey and Combining Gravitational Lensing I.; Dekker, H.; Garcia Dabo, C. E.; Hammersley, P.; with Stellar Dynamics and Stellar Population Izzo, C.; Mieske, S.; Rejkuba, M.; Rosati, P.; Analysis; Koopmans, L.; Czoske, O.; 149, 33 Sanchez-Janssen, R.; Selman, F.; Wolff, B.; 148, 13

68 The Messenger 151 – March 2013 An ALMA Survey of Submillimetre Galaxies in the Astronomical News ESO 50th Anniversary Activities; 149, 56 Extended Chandra Deep Field South: First Fellows at ESO; Rodrigues, M.; Sánchez-Janssen, Results; Swinbank, M.; Smail, I.; Karim, A.; Report on the Workshop “Ten Years of VLTI: From R.; Spezzi, L.; 149, 57 Hodge, J.; Walter, F.; Alexander, D.; Bertoldi, F.; First Fringes to Core Science”; Burtscher, L.; Personnel Movements; 149, 59 Biggs, A.; Brandt, N.; De Breuck, C.; Chapman, Delplancke, F.; Gilmozzi, R.; Melnick, J.; 147, 38 Switzerland Celebrates 30 Years of ESO Member- S.; Coppin, K.; Cox, P.; Danielson, A.; Danner- ESO Telescope Bibliography: New Public Interface; ship; Meylan, G.; Steinacher, M.; 150, 63 bauer, H.; Edge, A.; Ivison, R.; Greve, T.; Knudsen, Grothkopf, U.; Meakins, S.; 147, 41 Report on the Workshop “ESO@50 — The First K.; Menten, K.; Simpson, J.; Schinnerer, E.; Greetings from the ESO Council; Barcons, X.; 50 Years of ESO”; Walsh, J.; Emsellem, E.; West, Wardlow, J.; Weiss, A.; van der Werf, P.; 149, 40 147, 43 M.; 150, 64 Chemical Properties of a High-z Dusty Star-forming Report on the ESO Fellows Days in Chile 2011; Report on the Workshop “Science from the Next Galaxy from ALMA Cycle 0 Observations; Nagao, West, M.; Emsellem, E.; 147, 44 Generation Imaging and Spectroscopic Surveys”; T.; Maiolino, R.; De Breuck, C.; Caselli, P.; Call for Nominations for the European Extremely Rejkuba, M.; Arnaboldi, M.; 150, 67 Hatsukade, B.; Saigo, K.; 149, 44 Large Telescope Project Science Team; 147, 45 Retirement of Preben Grosbøl; Baade, D.; 150, 69 The La Silla–QUEST Southern Hemisphere Variability ESO Celebrates its 50th Anniversary; 147, 46 Announcement of the ESO Public Survey Catalogue Survey; Baltay, C.; Rabinowitz, D.; Hadjiyska, E.; Announcement of the Conference “ESO@50 – for Ultra-VISTA available from the Science Archive Schwamb, M.; Ellman, N.; Zinn, R.; Tourtellotte, The First 50 Years of ESO”; 147, 47 Facility; 150, 70 S.; McKinnon, R.; Horowitz, B.; Effron, A.; Nugent, Announcement of the ESO Workshop “Ecology of Staff at ESO; Gray, P.; 150, 71 P.; 150, 34 Blue Straggler Stars”; 147, 47 Fellows at ESO; Kains, N.; Galván-Madrid, R.; b Pictoris, a Laboratory for Planetary Formation Announcement of the ESO Workshop “Science from 150, 72 Studies; Lagrange, A.; Chauvin, G.; 150, 39 the Next Generation Imaging and Spectroscopic Presenting the ESO Story: One Hundred and Fifty RS Puppis: A Unique Cepheid Embedded in an Surveys”; 147, 48 Messengers; Madsen, C.; 150, 74 Interstellar Dust Cloud; Kervella, P.; Mérand, A.; Announcement of the ALMA Community Days: Announcement of the ESO Workshop “The Deaths Szabados, L.; Sparks, W. B.; Gallenne, A.; Havlen, Early Science in Cycle 1; 147, 48 of Stars and the Lives of Galaxies”; 150, 78 R. J.; Bond, H. E.; Pompei, E.; Fouqué, P.; Bersier, Announcement of the NEON Observing School Personnel Movements; 150, 78 D.; Cracraft, M.; 150, 46 2012; 147, 49 Vistas de la Galaxia; 150, 79 COSMOGRAIL: Measuring Time Delays of Gravita- Fellows at ESO; Westmoquette, M.; Bayo, A.; 147, 50 tionally Lensed Quasars to Constrain Cosmology; ESO Studentship Programme; 147, 52 Tewes, M.; Courbin, F.; Meylan, G.; Kochanek, C. Personnel Movements; 147, 53 S.; Eulaers, E.; Cantale, N.; Mosquera, A. M.; Renewable Energy for the Paranal Observatory; Asfandiyarov, I.; Magain, P.; van Winckel, H.; Weilenmann, U.; 148, 39 Sluse, D.; Keerthi, R. K. S.; Stalin, C. S.; Prabhu, Report on the ESO/IAG/USP Workshop “Circum- T. P.; Saha, P.; Dye, S.; 150, 49 stellar Dynamics at High Resolution”; Rivinius, T.; Breaking Cosmic Dawn: The Faintest Galaxy Carciofi, A.; Baade, D.; 148, 42 Detected by the VLT; Bradač, M.; Vanzella, E.; Hall, Report on the Workshop “Observing Planetary N.; Treu, T.; Fontana, A.; Gonzalez, A. H.; Clowe, Systems II”; Dumas, C.; Sterzik, M.; Melo, C.; D.; Zaritsky, D.; Stiavelli, M.; Clément, B.; 150, 53 Siebenmorgen, R.; Girard, J.; Mouillet, D.; 148, 44 Early ALMA Science Verification Observations of The ALMA Regional Centre in the Czech Republic Obscured Galaxy Formation at Redshift 47; Wagg, and the ALMA Winter School in Prague; J.; Wiklind, T.; Carilli, C.; Espada, D.; Peck, A.; Dąbrowski, B.; Karlický, M.; 148, 47 Riechers, D.; Walter, F.; Wootten, A.; Aravena, M.; Volunteer Outreach Activities at ESO Chile; The Barkats, D.; Cortes, J.; Hills, R.; Hodge, J.; ESO-Chile Outreach Volunteer Team; 148, 48 Impellizeri, V.; Iono, D.; Leroy, A.; Martin, S.; Inspiring Young Brazilian Astronomers at the La Silla Rawlings, M.; Maiolino, R.; McMahon, R. G.; Observatory; Meléndez, J.; 148, 50 Scott, K. S.; Villard, E.; Vlahakis, C.; 150, 56 Retirement of Klaus Banse; Ballester, P.; Péron, M.; Science Verification Datasets on the ALMA Science 148, 52 Portal; Testi, L.; Zwaan, M.; Vlahakis, C.; Corder, Staff at ESO; McPherson, A.; 148, 53 S.; 150, 59 Fellows at ESO; Vučković, M.; Beccari, G.; 148, 53 External Fellows at ESO; Tsamis, Y.; 148, 56 Announcement of the Conference “The First Year of ALMA Science”; 148, 57 ESO Fellowship Programme 2012/2013; 148, 58 The ALMA Newsletter; 148, 59 Personnel Movements; 148, 59 Report on the ALMA Community Days: Early Science in Cycle 1; Randall, S.; Testi, L.; Hatziminaoglou, E.; 149, 47 Report on the ESO Workshop “mm-wave VLBI with ALMA and Radio Telescopes around the World”; Falcke, H.; Laing, R.; Testi, L.; Zensus, A.; 149, 50 Some Reflections on the SPIE 2012 Symposium on Astronomical Telescopes + Instrumentation; Walsh, J.; 149, 54 Report on the Symposium “30 Years of Italian Participation to ESO”; Mainieri, V.; 149, 55

The Messenger 151 – March 2013 69 Author Index Bristow, P.; Baksai, P.; Balestra, I.; Dekker, H.; H Garcia Dabo, C. E.; Hammersley, P.; Izzo, C.; Mieske, S.; Rejkuba, M.; Rosati, P.; Sanchez- Hubrig, S.; Cowley, C. R.; Castelli, F.; González, J. F.; A Janssen, R.; Selman, F.; Wolff, B.; PILMOS: Wolff, B.; Elkin, V. G.; Mathys, G.; Schöller, M.; Pre-Image-Less Multi-Object Spectroscopy for The Chemistry and Magnetism of Young and Old Arnaboldi, M.; Rejkuba, M.; Retzlaff, J.; Delmotte, N.; VIMOS; 148, 13 Intermediate-mass Stars Observed with CRIRES; Hanuschik, R.; Hilker, M.; Hümmel, W.; Burtscher, L.; Delplancke, F.; Gilmozzi, R.; Melnick, 148, 21 Hussain, G.; Ivanov, V.; Micol, A.; Neeser, M.; J.; Report on the Workshop “Ten Years of VLTI: Petr-Gotzens, M.; Szeifert, T.; Comeron, F.; From First Fringes to Core Science”; 147, 38 Primas, F.; Romaniello, M.; ESO VISTA Public K Surveys — A Status Overview; 149, 7 C Kains, N.; Fellows at ESO; 150, 72 Kasper, M.; Beuzit, J.-L.; Feldt, M.; Dohlen, K.; B Campbell, R.; Kjær, K.; Amico, P.; 3D Visualisation Mouillet, D.; Puget, P.; Wildi, F.; Abe, L.; Baruffolo, of Integral Field Spectrometer Data; 148, 28 A.; Baudoz, P.; Bazzon, A.; Boccaletti, A.; Brast, Baade, D.; Retirement of Preben Grosbøl; 150, 69 Comerón, F.; Emerson, J.; Kuijken, K.; Zampieri, S.; R.; Buey, T.; Chesneau, O.; Claudi, R.; Costille, A.; Bacon, R.; Accardo, M.; Adjali, L.; Anwand, H.; Wright, A.; Filippi, G.; High-speed Bandwidth Delboulbé, A.; Desidera, S.; Dominik, C.; Dorn, R.; Bauer, S.-M.; Blaizot, J.; Boudon, D.; Brinchmann, between Europe and Paranal: EVALSO Demon- Downing, M.; Feautrier, P.; Fedrigo, E.; Fusco, T.; J.; Brotons, L.; Caillier, P.; Capoani, L.; Carollo, M.; stration Activities and Integration into Operations; Girard, J.; Giro, E.; Gluck, L.; Gonte, F.; Gojak, D.; Comin, M.; Contini, T.; Cumani, C.; Daguisé, E.; 147, 2 Gratton, R.; Henning, T.; Hubin, N.; Lagrange, Deiries, S.; Delabre, B.; Dreizler, S.; Dubois, J.-P.; Contini, T.; Epinat, B.; Vergani, D.; Queyrel, J.; Tasca, A.-M.; Langlois, M.; Mignant, D.L.; Lizon, J.-L.; Dupieux, M.; Dupuy, C.; Emsellem, E.; L.; Amram, P.; Garilli, B.; Kissler-Patig, M.; Lilley, P.; Madec, F.; Magnard, Y.; Martinez, P.; Fleischmann, A.; François, M.; Gallou, G.; Gharsa, Le Fèvre, O.; Moultaka, J.; Paioro, L.; Tresse, L.; Mawet, D.; Mesa, D.; Möller-Nilsson, O.; Moulin, T.; Girard, N.; Glindemann, A.; Guiderdoni, B.; Lopez-Sanjuan, C.; Perez-Montero, E.; Perret, V.; T.; Moutou, C.; O’Neal, J.; Pavlov, A.; Perret, D.; Hahn, T.; Hansali, G.; Hofmann, D.; Jarno, A.; Bournaud, F.; Divoy, C.; Teenage Galaxies; 147, 32 Petit, C.; Popovic, D.; Pragt, J.; Rabou, P.; Rochat, Kelz, A.; Kiekebusch, M.; Knudstrup, J.; Koehler, S.; Roelfsema, R.; Salasnich, B.; Sauvage, J.-F.; C.; Kollatschny, W.; Kosmalski, J.; Laurent, F.; Schmid, H. M.; Schuhler, N.; Sevin, A.; Sieben- Le Floch, M.; Lilly, S.; Lizon à L’Allemand, J.-L.; D morgen, R.; Soenke, C.; Stadler, E.; Suarez, M.; Loupias, M.; Manescau, A.; Monstein, C.; Nicklas, Turatto, M.; Udry, S.; Vigan, A.; Zins, G.; Gearing H.; Niemeyer, J.; Olaya, J.-C.; Palsa, R.; Parès, L.; Dąbrowski, B.; Karlický, M.; The ALMA Regional up the SPHERE; 149, 17 Pasquini, L.; Pécontal-Rousset, A.; Pello, R.; Petit, Centre in the Czech Republic and the ALMA Kerber, F.; Rose, T.; van den Ancker, M.; Querel, C.; Piqueras, L.; Popow, E.; Reiss, R.; Remillieux, Winter School in Prague; 148, 47 R. R.; Monitoring Atmospheric Water Vapour over A.; Renault, E.; Rhode, P.; Richard, J.; Roth, J.; de Zeeuw, T.; A Milestone for The Messenger in Paranal to Optimise VISIR Science Operations; Rupprecht, G.; Schaye, J.; Slezak, E.; Soucail, G.; ESO’s 50th Anniversary Year; 150, 2 148, 9 Steinmetz, M.; Streicher, O.; Stuik, R.; Valentin, H.; Dumas, C.; Sterzik, M.; Melo, C.; Siebenmorgen, R.; Kervella, P.; Mérand, A.; Szabados, L.; Sparks, Vernet, J.; Weilbacher, P.; Wisotzki, L.; Yerle, N.; Girard, J.; Mouillet, D.; Report on the Workshop W. B.; Gallenne, A.; Havlen, R. J.; Bond, H. E.; Zins, G.; News of the MUSE; 147, 4 “Observing Planetary Systems II”; 148, 44 Pompei, E.; Fouqué, P.; Bersier, D.; Cracraft, M.; Ballester, P.; Péron, M.; Retirement of Klaus Banse; RS Puppis: A Unique Cepheid Embedded in an 148, 52 Interstellar Dust Cloud; 150, 46 Baltay, C.; Rabinowitz, D.; Hadjiyska, E.; Schwamb, F Koopmans, L.; Czoske, O.; On the Inside of Massive M.; Ellman, N.; Zinn, R.; Tourtellotte, S.; McKin- Galaxies: The Sloan Lens ACS Survey and non, R.; Horowitz, B.; Effron, A.; Nugent, P.; The Falcke, H.; Laing, R.; Testi, L.; Zensus, A.; Report on Combining Gravitational Lensing with Stellar La Silla–QUEST Southern Hemisphere Variability the ESO Workshop “mm-wave VLBI with ALMA Dynamics and Stellar Population Analysis; 149, 33 Survey; 150, 34 and Radio Telescopes around the World”; 149, 50 Kuntschner, H.; Kümmel, M.; Westmoquette, M.; Barcons, X.; Greetings from the ESO Council; Fiorentino, G.; Tolstoy, E.; Diolaiti, E.; Valenti, E.; Ballester, P.; Pasquini, L.; The ESO 3D Visualisa- 147, 43 Cignoni, M.; Mackey, A. D.; Resolved Stellar tion Tool; 150, 30 Bayo, A.; Fellows at ESO; 147, 50 Populations with MAD: Preparing for the Era of Beccari, G.; Fellows at ESO; 148, 55 Extremely Large Telescopes; 147, 17 Boffin, H. M. J.; Jones, D.; Beletsky, Y.; van den Ancker, M.; Smoker, J.; Gadotti, D.; Saviane, I.; Moehler, S.; Ivanov, V. D.; Schmidtobreick, L.; G POPIPlaN: A Deep Morphological Catalogue of Newly Discovered Southern Planetary Nebulae; Galván-Madrid, R.; Fellows at ESO; 150, 73 148, 25 Gilmore, G.; Randich, S.; Asplund, M.; Binney, J.; Bradač, M.; Vanzella, E.; Hall, N.; Treu, T.; Fontana, Bonifacio, P.; Drew, J.; Feltzing, S.; Ferguson, A.; A.; Gonzalez, A. H.; Clowe, D.; Zaritsky, D.; Stia- Jeffries, R.; Micela, G.; Negueruela, I.; Prusti, T.; velli, M.; Clément, B.; Breaking Cosmic Dawn: The Rix, H.-W.; Vallenari, A.; Alfaro, E.; Allende-Prieto, Faintest Galaxy Detected by the VLT; 150, 53 C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Bramich, D.; Moehler, S.; Coccato, L.; Freudling, W.; Bragaglia, A.; Flaccomio, E.; François, P.; Irwin, Garcia-Dabó, C. E.; Møller, P.; Saviane, I.; On the M.; Koposov, S.; Korn, A.; Lanzafame, A.; Photometric Calibration of FORS2 and the Sloan Pancino, E.; Paunzen, E.; Recio-Blanco, A.; Digital Sky Survey; 149, 12 Sacco, G.; Smiljanic, R.; Van Eck, S.; Walton, N.; Brinks, E.; Leibundgut, B.; Mathys, G.; Report of the The Gaia-ESO Public Spectroscopic Survey; ESO OPC Working Group; 150, 20 147, 25 Gray, P.; Staff at ESO; 150, 71 Grothkopf, U.; Meakins, S.; ESO Telescope Bibliog- raphy: New Public Interface; 147, 41

70 The Messenger 151 – March 2013 L P T

Lagerholm, C.; Kuntschner, H.; Cappellari, M.; Patat, F.; Hussain, G.; Growth of Observing Testi, L.; Zwaan, M.; Vlahakis, C.; Corder, S.; Krajnovíc, D.; McDermid, R.; Rejkuba, M.; Programmes at ESO; 150, 17 Science Verification Datasets on the ALMA A Method to Deal with the Fringe-like Pattern in Science Portal; 150, 59 VIMOS-IFU Data; 148, 17 Tewes, M.; Courbin, F.; Meylan, G.; Kochanek, C. S.; Lagrange, A.; Chauvin, G.; b Pictoris, a Laboratory R Eulaers, E.; Cantale, N.; Mosquera, A. M.; for Planetary Formation Studies; 150, 39 Asfandiyarov, I.; Magain, P.; van Winckel, H.; Lo Curto, G.; Pasquini, L.; Manescau, A.; Holzwarth, Ramsay, S.; Provisional Acceptance of KMOS; Sluse, D.; Keerthi, R. K. S.; Stalin, C. S.; Prabhu, R.; Steinmetz, T.; Wilken, T.; Probst, R.; Udem, T.; 149, 16 T. P.; Saha, P.; Dye, S.; COSMOGRAIL: Measuring Hänsch, T. W.; González Hernández, J.; Esposito, Randall, S.; Testi, L.; Hatziminaoglou, E.; Report on Time Delays of Gravitationally Lensed Quasars to M.; Rebolo, R.; Canto Martins, B.; Renan de the ALMA Community Days: Early Science in Constrain Cosmology; 150, 49 Medeiros, J.; Astronomical Spectrograph Calibra- Cycle 1; 149, 47 The ESO-Chile Outreach Volunteer Team; Volunteer tion at the Exo-Earth Detection Limit; 149, 2 Rejkuba, M.; Arnaboldi, M.; Report on the Workshop Outreach Activities at ESO Chile; 148, 48 Lützgendorf, N.; Kissler-Patig, M.; de Zeeuw, T.; “Science from the Next Generation Imaging and Tsamis, Y.; External Fellows at ESO; 148, 56 Baumgardt, H.; Feldmeier, A.; Gebhardt, K.; Jalali, Spectroscopic Surveys”; 150, 67 B.; Neumayer, N.; Noyola, E.; The Search for Rivinius, T.; Carciofi, A.; Baade, D.; Report on the Intermediate-mass Black Holes in Globular Clus- ESO/IAG/USP Workshop “Circumstellar Dynamics V ters; 147, 21 at High Resolution”; 148, 42 Rodrigues, M.; Fellows at ESO; 149, 57 Vučković, M.; Fellows at ESO; 148, 53

M S W Madsen, C.; Presenting the ESO Story: One Hundred and Fifty Messengers; 150, 74 Sana, H.; de Koter, A.; Garcia, M.; Hartoog, O.; Wagg, J.; Wiklind, T.; Carilli, C.; Espada, D.; Peck, A.; Mainieri, V.; Report on the Symposium “30 Years of Kaper, L.; Tramper, F.; Herrero, A.; Castro, N.; Riechers, D.; Walter, F.; Wootten, A.; Aravena, M.; Italian Participation to ESO”; 149, 55 X-shooter Spectroscopy of Massive Stars in the Barkats, D.; Cortes, J.; Hills, R.; Hodge, J.; McPherson, A.; Gilmozzi, R.; Spyromilio, J.; Kissler- Local Group and Beyond; 148, 33 Impellizeri, V.; Iono, D.; Leroy, A.; Martin, S.; Patig, M.; Ramsay, S.; Recent Progress Towards Sánchez-Janssen, R.; Fellows at ESO; 149, 57 Rawlings, M.; Maiolino, R.; McMahon, R. G.; the European Extremely Large Telescope (E-ELT); Saviane, I.; Held, E. V.; Da Costa, G. S.; Sommariva, Scott, K. S.; Villard, E.; Vlahakis, C.; Early ALMA 148, 2 V.; Gullieuszik, M.; Barbuy, B.; Ortolani, S.; New Science Verification Observations of Obscured McPherson, A.; Staff at ESO; 148, 53 Surprises in Old Stellar Clusters; 149, 23 Galaxy Formation at Redshift 47; 150, 56 Meléndez, J.; Inspiring Young Brazilian Astronomers Schödel, R.; Girard, J. H.; Holographic Imaging: Walsh, J.; Testi, L.; First published ALMA Early at the La Silla Observatory; 148, 50 A Versatile Tool for High Angular Resolution Science Cycle 0 Result — Mapping of the Meylan, G.; Steinacher, M.; Switzerland Celebrates Imaging; 150, 26 Fomalhaut Debris Disc; 148, 32 30 Years of ESO Membership; 150, 63 Schwan, D.; Kneissl, R.; Ade, P.; Basu, K.; Bender, Walsh, J.; Some Reflections on the SPIE 2012 Morelli, L.; Corsini, E. M.; Pizzella, A.; Dalla Bontà, A.; Bertoldi, F.; Böhringer, H.; Cho, H.-M.; Chon, Symposium on Astronomical Telescopes + E.; Coccato, L.; Méndez-Abreu, J.; Cesetti, M.; G.; Clarke, J.; Dobbs, M.; Ferrusca, D.; Flanigan, Instrumentation; 149, 54 Stellar Populations of Bulges in Galaxies with Low D.; Halverson, N.; Holzapfel, W.; Horellou, C.; Walsh, J.; Emsellem, E.; West, M.; Report on the Surface-brightness Discs; 149, 28 Johansson, D.; Johnson, B.; Kennedy, J.; Workshop “ESO@50 — The First 50 Years of Kermish, Z.; Klein, M.; Lanting, T.; Lee, A.; Lueker, ESO”; 150, 64 M.; Mehl, J.; Menten, K.; Muders, D.; Pacaud, F.; Weilenmann, U.; Renewable Energy for the Paranal N Plagge, T.; Reichardt, C.; Richards, P.; Schaaf, R.; Observatory; 148, 39 Schilke, P.; Sommer, M.; Spieler, H.; Tucker, C.; West, M.; Emsellem, E.; Report on the ESO Fellows Nagao, T.; Maiolino, R.; De Breuck, C.; Caselli, P.; Weiss, A.; Westbrook, B.; Zahn, O.; APEX–SZ: Days in Chile 2011; 147, 44 Hatsukade, B.; Saigo, K.; Chemical Properties of The Atacama Pathfinder EXperiment Sunyaev– Westmoquette, M.; Fellows at ESO; 147, 50 a High-z Dusty Star-forming Galaxy from ALMA Zel’dovich Instrument; 147, 7 Woltjer, L.; van der Laan, H.; Giacconi, R.; Cesarsky, Cycle 0 Observations; 149, 44 Sirey, R.; ESO 50th Anniversary Gala Dinner; 150, 7 C.; Reflections from Past Directors General; Spezzi, L.; Fellows at ESO; 149, 58 150, 3 Storm, J.; Gieren, W.; Fouqué, P.; Barnes, T. G.; Granzer, T.; Nardetto, N.; Pietrzyński, G.; Queloz, D.; Soszyński, I.; Strassmeier, K. G.; Weber, M.; Determining the Cepheid Period–Luminosity Relation Using Distances to Individual Cepheids from the Near-infrared Surface Brightness Method; 147, 14 Swinbank, M.; Smail, I.; Karim, A.; Hodge, J.; Walter, F.; Alexander, D.; Bertoldi, F.; Biggs, A.; Brandt, N.; De Breuck, C.; Chapman, S.; Coppin, K.; Cox, P.; Danielson, A.; Dannerbauer, H.; Edge, A.; Ivison, R.; Greve, T.; Knudsen, K.; Menten, K.; Simpson, J.; Schinnerer, E.; Wardlow, J.; Weiss, A.; van der Werf, P.; An ALMA Survey of Submilli- metre Galaxies in the Extended Chandra Deep Field South: First Results; 149, 40

The Messenger 151 – March 2013 71 ESO, the European Southern Observa- Contents tory, is the foremost intergovernmental astronomy organisation in Europe. It Telescopes and Instrumentation is supported by 15 countries: Austria, P. Hammersley et al. – Upgrading VIMOS — Part II 2 Belgium, Brazil, the Czech Republic, A. Klotz et al. – Six Years of Science with the TAROT Telescope at La Silla 6 Denmark, France, Finland, Germany, Y. Yang et al. – Accurate Sky Continuum Subtraction with Italy, the Netherlands, Portugal, Spain, Fibre-fed Spectrographs 10 Sweden, Switzerland and the United R. Arsenault et al. – Delivery of the Second Generation VLT Kingdom. ESO’s programme is focused Secondary Mirror (M2) Unit to ESO 14 on the design, construction and opera- M. Zwaan et al. – ALMA Completes Its First Science Observing Season 20 tion of powerful ground-based observ- R. Sharples et al. – First Light for the KMOS Multi-Object Integral-Field ing facilities. ESO operates three obser- Spectrometer 21 vatories in Chile: at La Silla, at Paranal, site of the Very Large Telescope, and Astronomical Science at Llano de Chajnantor. ESO is the G. Gilmore et al. – Boötes-I, Segue 1, the Orphan Stream and CEMP-no Stars: European partner in the Atacama Large Extreme Systems Quantifying Feedback and Chemical Evolution Millimeter/submillimeter Array (ALMA) in the Oldest and Smallest Galaxies 25 under construction at Chajnantor. M. T. Botticella et al. – SUDARE at the VST 29 Currently ESO is engaged in the design L. Coccato et al. – Disentangling the Kinematics and Stellar Populations of of the European Extremely Large Counter-rotating Stellar Discs in Galaxies 33 Telescope. F. D’Eugenio et al. – Angular Momentum of Galaxies in the Densest Environments: A FLAMES/GIRAFFE IFS study of the Massive Cluster The Messenger is published, in hard- Abell 1689 at z = 0.18 37 copy and electronic form, four times L. Guzzo et al. – VIPERS: An Unprecedented View of Galaxies and a year: in March, June, September and Large-scale Structure Halfway Back in the Life of the Universe 41 December. ESO produces and distributes a wide variety of media c onnected Astronomical News to its activities. For further information, H. Boffin et al. – Report on the Workshop “Ecology of Blue Straggler Stars” 48 including postal subscription to The L. Testi, P. Andreani – Report on the Conference “The First Year of Messenger, contact the ESO education ALMA Science” 50 and Public Outreach Department at the E. Fedrigo – Report on the ESO Workshop “Real Time Control for following address: Adaptive Optics 2012” 55 R. Hanuschik – Llullaillaco and Paranal’s Skyline 58 ESO Headquarters L. L. Christensen – Hännes Heyer Retires 61 Karl-Schwarzschild-Straße 2 New Implementation of the ESO Data Access Policy 62 85748 Garching bei München Fellows at ESO – L. Cortese, G. Tremblay 63 Germany ESO Studentship Programme 65 Phone +498932006-0 Announcement of the ESO Workshop “Deconstructing Galaxies: Structure [email protected] and Morphology in the Era of Large Surveys” 66 Announcement of the ESA/ESO Workshop “SCIENCE OPERATIONS 2013: The Messenger: Working Together in Support of Science” 66 Editor: Jeremy R. Walsh; Announcement of the Workshop “400 years of Stellar Rotation” 67 Design, Production: Jutta Boxheimer; Personnel Movements 67 Layout, Typesetting: Mafalda Martins; Graphics: Roberto Duque. Annual Index 2012 (Nos. 147–150) 68 www.eso.org/messenger/

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Unless otherwise indicated, all images Front cover: The spiral galaxy NGC 2442 is shown in a colour composite from in The Messenger are courtesy of ESO, images taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope. except authored contributions which Images in two broadband filters (B and V) and a narrowband, isolating the emission are courtesy of the respective authors. lines Hα and [N ii], were combined. This peculiar tidally distorted SAB spiral galaxy is situated at about 21 Mpc, has a low ionisation active galactic nucleus (LINER) © ESO 2013 and a core collapse supernova was observed in the southern spiral arm (SN 1999ga). ISSN 0722-6691 See Photo Release eso1115 for more details.