eam) T ayne Orchiston) ayne T. AAOmega team) AAOmega Andropoulos & W & Andropoulos AA AAOmega Aust. (Jenny Aust. est room at the at room est ill Saunders for the for Saunders ill s final spectrum (Heath Jones and the 6dFGS the and Jones (Heath spectrum final s eam) T NEWSLETTER VE akes it akes AAOmega (Brent Miszalski et al.) et Miszalski (Brent AAOmega 2006 alled in the Coude W Coude the in alled Y AAOmega inst AAOmega elocity experiment (The RA (The experiment elocity An r~22 radio selected emission line galaxy from science verification time. exposure source on hours 2 for shuffle and nod using data new field configuration algorithm for A Melbourne Observatory & the genesis of astrophysics in astrophysics of genesis the & Observatory Melbourne The Radial V Radial The AAOmega commissioning update (Rob Sharp & W & Sharp (Rob update commissioning AAOmega IRIS2 and the global star formation rate over most of history (Rob Sharp et al.) et Sharp (Rob history of most over rate formation star global the and IRIS2 al.) et Chiu (Kuenley SDSS and 2dF using quasars of age the of peak the Probing t Survey Galaxy 6dF the era: an of End Successful commissioning of commissioning Successful 24 18 14 21 11 3 6

contents

NUMBER NUMBER 109 FEBRUAR ANGLO-AUSTRALIAN OBSERVATORY DIRECTOR DIRECTOR’S MESSAGE

AAOmega’s final commissioning run and Science Verification observations were completed last night. The article by Rob Sharp and Will Saunders on page 21 of this newsletter reports on the commissioning process and provides the latest information on the performance of the instrument. The bottom line is that AAOmega appears to be performing very close to specification, and that the remaining issues are expected to be resolved prior to the start of the first allocated science observations at the end of February. The nod & shuffle and cross-beam switching ’ S MESSAGE S modes have both been fully commissioned, and initial tests of mini-shuffling, allowing nod & shuffle observations with all fibres, indicate that this important mode will also work as intended. This is an excellent outcome and a tribute to the extraordinary efforts that the AAOmega team have put into designing, building and commissioning the instrument.

AAOmega Science Verification data were taken over 8 nights for 11 programs selected by the service time committee, showcasing the range of AAOmega’s capabilities using a wide variety of instrument setups. These observations will be reduced and made publicly available as soon as possible. The first allocated science observations with AAOmega will begin on 22 February. The SPIRAL integral field unit for AAOmega will be commissioned later in the semester, with the first allocated science observations beginning on 27 June.

Semester 06A is the first in which time was allocated by the unified Anglo-Australian Time Allocation Committee (AATAC; see page 17 of the last newsletter). The Chair of AATAC, Martin Asplund, reports outcomes from the AATAC meeting on page 29 here. There was a healthy over-subscription for AAT time, and a strong response (11 proposals) to the call for large observing programs. In this first round, AATAC has approved components of one large program outright (the Anglo-Australian Planet Search) and made allocations of time for pilot observations to four other large programs planning to use AAOmega.

Depending on the outcomes of these pilot studies, AATAC may choose to select one or more of these programs for long-term support, or it may select another large program proposal from among the new proposals submitted for Semester 06B. These large programs should produce much of the flagship science from the AAT over the next few years, just as the 2dF galaxy and quasar surveys did in the recent past, as reflected, for example, by the news article in Nature (2006, 439, 251) comparing the impact of various telescopes.

The AAO is about to undergo a significant and necessary review by the Australian Government. The review will focus on the future of the AAO, both in terms of positioning in the run-up to the foreshadowed withdrawal of the UK from the AAT Agreement in 2010, and the form the organization will take thereafter, when the AAO becomes a wholly Australian entity.

The review is being conducted under the auspices of the Minister for Education, Science and Training, who has appointed a review panel consisting of Dr Ian Chessell (chair; former Chief Defence Scientist), Professor Garth Illingworth (UCSC/Lick) and Professor John Storey (UNSW). The panel will consider the recommendations of the Australian Astronomy Decadal Plan 2006–2015 and take as input submissions from all interested parties. The announcement of the review and the call for submissions will appear on the Department of Education, Science and Training website (http://www.dest.gov.au/). In order to provide focus to submissions, the panel will release an issues paper, discussing the background to the review and highlighting the critical concerns, in early February. Submissions may be made to the review panel via the secretariat at DEST ([email protected].) before the deadline, 24 March. The review panel will meet and visit the AAO for four days 10–13 April, during which time they will talk to the major stakeholders in the AAO, including the AAT Board, representatives of the user community and AAO staff. It is expected that the panel will report back and make recommendations to the Minister by June 2006.

It is important that all stakeholders in the AAO, and especially Australians, respond to this opportunity to shape the long-term future of the Observatory.

Matthew Colless

ANGLO-AUSTRALIAN OBSERVATORY page 2 NEWSLETTER FEBRUARY 2006 IRIS2 AND THE GLOBAL STAR 6.00•10−17

FORMATION RATE OVER MOST OF HIGHLIGHTS SCIENCE HISTORY 4.00•10−17

Rob Sharp (AAO), Andrew Bunker 2.00•10−17 (Exeter), Michelle Doherty (ESO), Ian Parry (Cambridge) & Gavin Dalton −2.34•10−24 (Oxford) −2.00•10−17

Since the first appearance of the notorious “Madau-Lilly” −4.00•10−17 diagram in the mid-1990s (Madau et al. 1996, Lilly et −6.00•10−17 al. 1996; Pei & Fall 1995), which represented the first 1.195•104 1.200•104 1.205•104 1.210•104 1.215•104 1.220•10 Wavelength (A) attempts to trace the variation of the global star formation rate over the history of the Universe via comparison of star-formation rates at different redshifts, astronomers Figure 2: A CIRPASS MOS spectrum for an H-alpha emitter in SSA22. H-alpha is clearly visible, and at the expected have puzzled over the true form of the phenomenon. wavelength. With star-formation indicators plagued by innumerable issues (dust reddening, indicator calibration one must head into the depths of the deep, but uncertainties, dust reddening, initial mass function (IMF) depressingly not very dark, forest of OH air-glow uncertainties, dust reddening, underlying absorption emission lines in the near IR (Iwamuro et al. 2001). spectra, dust reddening... pretty much everything really) requiring the use of large correction factors, it is easy Our collaboration has used the CIRPASS (Parry et al. to infer quite the wrong history when contrasting 2004; Doherty et al. 2004) IR fiber MOS system (both observations made with different techniques. Ideally one at the AAT and the WHT), initially bringing the AAO- wishes to take one reliable and well understood (or at FOCAP system out of retirement, and lately the IRIS2 the very least uniformly biased) tracer of star-formation slit mask system, to pursue H-alpha star-formation rates and observe this tracer over an extended redshift range. (and H-beta/[OIII] in higher redshift source, allowing limits to dust reddening and metallicity effects to be tested) Unfortunately one of the most widely used tracers, over the redshift range 0.8

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 3 FEBRUARY 2006 suppression instruments, one may well be suppressing AAOmega commissioning. the very signal one seeks.

SCIENCE HIGHLIGHTS The future IRIS2 observing The analysis of the observations from both the AAT The IRIS2 slit mask acquisition and observing system and WHT is coalescing into a coherent picture of the is impressive. With minimal effort the Skycat-GAIA and z~1 star formation rate, as measured via H-alpha IRIS2 interface software allows alignment of the mask, (Doherty et al. in prep). Our results will be presented in translation and rotation, with a number of fiducial stars shortly in the context of similar works (Glazebrook et in each field. After some initial experimentation the al. 1999; Tresse et al. 2002). process became rapid and reliable allowing confidence IR MOS spectroscopy is coming of age. Large format in the result, which greatly reduced the stress levels for IR arrays give us the real-estate to record multiple, our inexperienced IRIS2 observers (IRIS2 is somewhat different to 2dF!), associated with the multi hour moderate resolution spectra at once while improved exposures needed to record the H-alpha emission. In data quality allows one to push the limits of sensitivity required to make useful comparison with alternate SFR fact if one overlooks some frantic activity associated indicators. The wealth of data available from optical with a 2am GRB override, smooth, confident observing would appear to be a feature of the IRIS2 system. redshift surveys at z>0.8 allows one to tune sample selection to take maximum advantage of the dark sky Unfortunately the excellent ORAC-DR software, which between OH lines, taking much of the guesswork out handles more common IRIS2 observing modes, does of the measurement. not reduce slit-mask data. IDL scripts and common IRAF While we all wait with bated breath for the tasks were used to process the data (cosmic ray rejection, A–B position beam switching, rectification of implementation of OH suppression fibers (Bland- wavelength scales and long-slit sky subtraction). Initial Hawthorn 2005), the immediate future promises much through the use of fantastic facilities such as the soon- inspection of the data at the telescope, using even these to-be-commissioned FMOS/Echidna system at Subaru. rather primitive tools, revealed numerous H-alpha, and several [OIII] emission lines (see Figure 4). The detailed With the huge multiplex of Echidna and the light grasp analysis of the data has been somewhat delayed by of an 8 meter telescope, FMOS presents the tantalizing

Figure 3: To the left we see a raw IRIS2 slit mask exposure. 15 minutes on sky is required for the interline regions to be limited, not by readnoise, but by sky/scattered light levels. Cosmic ray rejection was performed using a custom IDL routine which owes its origins to the IRAF/STSDAS task CALNICA. Due to the catastrophic failure of the IRIS2 science grade detector earlier in the year, the engineering grade detector is seen here. There are a number of cosmetic defects in the detector. However, many of these are removed by beam switching yielding, for the most part, excellent data. The four fiducial stars used to align the mask can be clearly identified. Individual objects are allocated 8 arcsecond slits with objects selected to give the maximum target density on the mask. Slits are then grown outwards to fill in the gaps where no new object slits could be placed, yielding a longer spectrum for a better long slit sky subtraction. Observations are performed with the target nodded between two positions on the slit 4 arcseconds, 10 pixels, apart. To the right we see the result of a single A–B position 15 minute beam switch. First order sky subtraction of this sky limited frame is good. A full long slit subtraction is performed after wavelength rectification. Using the beamswitch technique removes the need for independent dark exposures.

ANGLO-AUSTRALIAN OBSERVATORY page 4 NEWSLETTER FEBRUARY 2006 SCIENCE HIGHLIGHTS

Figure 4: A number of H-alpha emitters are clearly visible in this IRIS2 J band slit mask image. This section of a beam-switched A-B frame, at a mid point of the data reduction process, shows clear H-alpha emission from two sources in SSA22. The field also contains a number of H-beta/[OIII] emitters, not shown here. A close up of the long slit sky subtracted spectrum of one of the sources, along with its final summed spectra, is also shown.

opportunity to build upon the work described here, Iwamuro F. et al. 2001 PASJ 53 355 building larger samples, and to further address questions, Lilly S.J, Le Fevre O., Hammer F. & Crampton D 1996 ApJ 460L 1 such as the reddening and metallicity effects, raised by Maihara T. et al. 1993 PASP 105 940 H-beta/[OIII] observations (Shapley, Coil & Ma 2005). Madau P., Ferguson H.C., Dickinson M.E., Giavalisco M., Steidel C.C. & Fruchter A. 1996 MNRAS 283 1388 References Parry I., et al. 2004 SPIE 5492 1135 Pei Y.C. & Fall S.M. 1995 ApJ 454 69 Bland-Hawthorn J. 2005 AAO newsletter 108 4 Shapley A., Coil A.L. & Ma C.-P. 2005 ApJ 635 1006 Doherty M., Bunker A., Sharp R. et al. 2004 MNRAS 354L 7 Tresse L., Maddox S.J., Le Fevre O., Cuby J.-G. 2002 Glazebrook K., Blake C., Economou F., Lilly S. & Colless M. MNRAS 337 369 1999 MNRAS 306 843

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 5 FEBRUARY 2006 PROBING THE PEAK OF THE AGE few brightest quasars that can be found [2].

SCIENCE HIGHLIGHTS SCIENCE OF QUASARS USING 2DF AND Quasars are intimately linked to the populations of black SDSS holes that occupied the early universe, and to the later Kuenley Chiu, Karl Glazebrook (JHU), populations of galaxies we see today. Looking back from Brian Boyle (ATNF), Scott Croom (AAO), the present in time and distance, one of the most striking Wei Zheng (Exeter), Terry Bridges first observations about quasars was their rising number (Queens), Rob Sharp (AAO), Zlatan density with increasing redshift [3]. Beyond z~3, quasar Tsvetanov (JHU) numbers were also found to decrease rapidly [4]. More recent work by collaborations such as the 2dF Quasar Forty years ago, a new type of object began to be Redshift Survey [5] and the SDSS Spectroscopic Quasar observed by astronomers curious about unusual radio- Survey [6] have produced the clearest picture of quasar emitting sources on the sky [1]. These objects – evolution yet, identifying a peak in the numbers of quasars compact and bright in visible light images, yet also around approximately z~2.5 – the epoch of maximum puzzlingly radio-loud unlike stars – were eventually quasar activity in the universe. Thus, what we envision understood to be highly luminous sources at previously now is that the age of black hole formation in the early unimagined cosmological distances. Given the name universe led to the conditions making quasar activity quasars (and synonymously QSOs and/or AGNs), they possible, and that quasars grew and then declined with opened a new frontier of extragalactic observations with time, giving way to the age of galaxies that we ourselves their extreme brightness and redshifts. In the decades occupy. since those first basic discoveries, quasars have played a leading role in expanding our observable horizon. But what is the detailed chronology of this sequence of Indeed, with quasars steadily illuminating the path events? And in what particular order did the mass that towards the high redshift domain, these once rare and formed luminous structures collapse? The exact times exotic objects have become regarded as common tools at which these various populations flourished hold for observers seeking information about the environment, consequences for constraining the rate of structure composition, and state of the distant universe itself. formation in the early universe – currently a topic of Recent discoveries have brought us to the frontier of significant interest as these several areas converge with z~6 using ground-based telescopes, where the epoch the accumulation of theoretical models and observational of reionization has been tantalizingly suggested by the evidence.

Fig.1 At z~2–3, the spectra of quasars appear very similar to normal Galactic stars when sampled by broadband photometric filters. Optical surveys select candidates for followup spectroscopy based on colors, and in such cases, cannot distinguish between high-value quasar targets, and the relatively more common stars.

ANGLO-AUSTRALIAN OBSERVATORY page 6 NEWSLETTER FEBRUARY 2006 SCIENCE HIGHLIGHTS SCIENCE

3.0 2.8 2.6 2.0 2.2 2.4

u-g

Fig.2 As quasar colors evolve with redshift (solid track) and collide with those of stars, for example at z~2.5, spectroscopic surveys are overwhelmed by the number of candidates for followup. Surveys such as the SDSS must exclude such contaminated areas (central narrow box with labels 2.2 to 2.6).

Our team sought to carry out a project that might shed peak of their evolution, using SDSS imaging coupled light on the question of when exactly quasars with a dedicated spectroscopic discovery survey. We experienced their maximum period of activity. For would deliberately focus on these contaminated regions despite the importance of the z~2–3 redshift range for of quasar color space in order to recover hidden quasar evolution, the peak has remained only roughly populations of quasars and improve the estimates of constrained due to a coincidence of quasar and stellar the parent population of quasars around the peak of colors and shapes. At these and other problematic activity. redshift ranges, the colors of normal Galactic stars muddy the task of distinguishing quasar candidates in Our method was to begin with imaging data of the Sloan imaging and following them up with spectroscopic Digital Sky Survey and follow up using the spectroscopic resources. Large numbers of stars reduce the efficiency capabilities of the 2dF instrument. Given the possibility of quasar surveys in these regimes, and any consistently that we would have hundreds of targets per square selected sample is overwhelmed with possible targets degree, the unique 2dF instrument provided the only (see Figures 1 and 2). Given finite spectroscopic spectroscopic resource capable of executing such a resources, survey groups naturally concentrate on program. With the ability to rapidly configure (and targets with the highest success rate. The SDSS, for reconfigure) 400 fibers over a wide field, and reach limiting example, observes only 10% of the possible targets in magnitudes close to the SDSS imaging limit within a the z~2.5 area because of the heavy contamination. reasonable exposure time, 2dF was perfectly suited to As a result, in all of the catalogs of quasar populations carrying out the program we envisioned. at z~2.5 to date, a significant drop in quasar numbers On the surface, our task seemed simple – to observe is reported. And while a decrease in numbers may be as many targets as possible in the contaminated region authentic in part, its true magnitude and location in shown in Figure 2. But in practice this presented some redshift space is hidden behind the difficulty of observing interesting technical challenges, and gave us excellent these candidates and confirming their identities as experience in merging SDSS and 2dF practices. Our quasars. main task before observation was to design the efficient In a program generously allocated time on the 2dF photometric color selections that would create suitable instrument at the AAT, we conducted this project to samples for input to 2dF. In the area where z~2.5 identify a large sample of quasars around the z~2.5 quasars are found, the number of candidates rises

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 7 FEBRUARY 2006 been found, which are believed to be even rarer objects. The 2dF’s split spectrograph capability SCIENCE HIGHLIGHTS SCIENCE allowed us to observe both z~2.5 and z~5.6 targets simultaneously, by placing a blue spectral grating in spectrograph 1 and a red grating in spectrograph 2. Because z~2.5 targets are identifiable with either grating, this allowed us to implement both programs in a resource sharing scheme, so that an efficient allocation of fibers would benefit both programs. The interesting fiber allocation issues posed by this split spectrograph scheme, as well as the successful observation of a z=5.03 quasar, were detailed in the September 2001 issue of this newsletter.

Another observational enhancement we studied and implemented was the “slow-nodding” procedure used to help reduce the effect of the many night sky lines approaching the near infrared, which u-g otherwise affected our red grating identifications seriously. As is all too familiar to astronomers Fig. 3 Our selection strategy tuned the number of targets observable in each 2dF field by adjusting the candidate cut depth working in the optical where λ>8000, and in the into the stellar locus. near-infrared, the increasing strength and number of night sky lines severely hinders low resolution dramatically as the stellar locus is encountered. Clearly, spectroscopy at these wavelengths. Specifically, it is the extent of the selection into this contaminated area the variability of the strength of the lines which causes would determine the number of objects produced for inaccurate subtraction of their flux, and thus distorts observation. Figure 3 illustrates our candidate cutting the spectrum of the underlying object. Slow-nodding strategy. Using an adjustable top which could be involves observing a blank field (in each 2dF fiber) translated up or down in SDSS g-r color, we were able between 2 object observations for the same exposure to increase or decrease the number of candidates time. The roughly contemporaneous observation of sky produced. Calculations of candidate number versus this adjustable selection criterion, as well as magnitude, gave us the needed information to design the appropriate color and magnitude cuts to match the number of targets to the 2dF fiber density (as seen in Figure 4). And with a “floating” magnitude limit in each field, the 2dF configuration software could be assured of a sufficient number of candidates even in naturally under- dense patches of sky.

One interesting technical aspect of 2dF benefited our project and is worth a mention – as a side program, in addition to this z~3 work, we pursued quasars at z~5.4–5.8 located in another stellar-contaminated region of color space. The discovery of this range of quasars is hindered by a similar collision of the quasar track with the stellar locus in SDSS riz color space. Indeed, only Fig. 4 The 2dF candidate number density (contour lines) was calculated versus color selection and magnitude. By fixing the color selection across two quasars in this broad redshift range have the sample, and allowing the magnitude limit to float, under- and over- been discovered to date [7,8] due to this dense fields could be accommodated by the 2dF configure program. Horizontal line indicates our nominal survey limit of i=21.0 problem. In contrast, 15+ z~6 quasars have

ANGLO-AUSTRALIAN OBSERVATORY page 8 NEWSLETTER FEBRUARY 2006 object spectra were inspected, with

most of these being normal Galactic HIGHLIGHTS SCIENCE stars. 340 quasars were found in the redshift range z=1.95 to 3.28. 5 additional quasars were discovered in the range z=4.44 to z=5.28, selected and observed by the experimental z~5.6 high redshift observing program carried out simultaneously. The quasars span a redshift range of 1.95 to 5.28, apparent

mi magnitudes of 17.46 to 21.85, and

absolute Mi(z=2) magnitudes of –28.94 to –24.34, as shown in Figure 6.

A number of interesting points have emerged from the luminosity functions and calculated density functions so far, though our analysis is ongoing. We Fig. 5 The improvement of “slow-nodding” sky subtraction is illustrated. A 2dF sky exposure is taken between two object exposures, allowing accurate have found that the binned luminosity sky to be measured for each object, through the identical fiber, prism, and function derived from the 340 quasars complete optical path. discovered in this work shows an interesting redshift evolution compared acquired in this way can be used to better subtract the to the analytic double power law fit by Richards et al. sky flux affecting the adjacent object observations. This (which is very similar to that of Croom et al. (2004) at approach is more successful than use of the 30 or so low redshifts). The data suggest that the redshift sky fibers allocated by default to each 2dF field, because evolution of the quasar space density is both more rapid the separate sky observation proceeds through the than previously found, and reaches an absolute peak identical prism, fiber, and overall optical path as each density higher (and later) than Richards et al. Our object observed, thus making the individual subtraction sparsely populated bins at redshifts greater than z~3 as accurate as possible. Figure 5 illustrates the promising results of this technique.

With the observation strategy planned, we travelled to the AAT for a dozen nights of observing spread over two years. The central theme of the observing could be summed up in one word: stars. Plenty of stars – we found more normal stars than could ever be desired by an astronomer. But in addition, for each night of observing four to six 2dF fields, we also discovered approximately 30 new z~2.5 quasars – a rate far exceeding the SDSS automated quasar survey per area, precisely because our program chose to focus on this peak range of their numbers. In all, 70 fields were exposed on the 2dF instrument, each with a typical fiber Fig. 6 The sample of 340 new z~2.5 quasars discovered in this work. Objects allocation of 360 program objects, are plotted in redshift versus absolute magnitude, using Mi(z=2) convention of 30 sky, 4 guide stars, and about 10 Richards et al. 2006. Our survey limit of i=21.0 is shown as the solid line, contrasted with the survey limits of the SDSS spectroscopic quasar survey, at broken fibers. A total of some 24500 i=19.1 (low-z) and i=20.2 (high-z).

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Fig. 7 Bright quasar space density versus redshift. The results of several groups are shown in a composite here, illustrating the general rise and fall of quasar numbers versus redshift, including the latest work of Croom et al. (2004) and Richards et al. (2006) constraining the peak of activity around z~2.5. Our discovered quasar sample (three red points with errors) suggests that the peak occurs both higher and later in redshift than found in previous work, around z~2.8.

make it difficult to give definite statements about the central refitted component of the AAOmega instrument, endpoint of the trend and at what redshift the quasar a more sensitive multi-object and integral-field numbers begin their expected decline again. However, spectrograph for the AAT. Throughput, spectral we are intrigued that the redshift peak of the quasar resolution, and stability have improved, and the activity is later than expected from previous models – instrument promises to continue producing the i.e. at higher redshifts, around z~2.8 rather than z~2.4 groundbreaking large, faint, and high-redshift sample as predicted by Richards et al. and others (see discoveries that marked 2dF as a unique astronomical Figure 7). facility. The several collaborative groups involving SDSS and 2dF have already begun planning the productive As we had hoped, the excellent capabilities of 2dF use of AAOmega, and with new surveys such as UKIDSS coupled with the SDSS allowed us to examine the providing a rich source of targets, we will undoubtedly important redshift range where quasars have their most witness many novel results from this instrument for active period of evolution. The natural difficulty of selecting years to come. targets in this area resulted in an observationally intensive, but valuable program that produced a sample References of 340 quasars around z~2.5. In addition to publishing [1] Schmidt, M. 1963, Nature, 197, 1040 the catalog of discovered objects, a study of the [2] Fan, X., et al. 2004, AJ, 128, 515 luminosity function will be forthcoming – we have found [3] Boyle, B. J., Shanks, T., & Peterson, B. A. 1988, MNRAS, 235, 935 quite interesting preliminary results pointing to a peak [4] Schneider, D.P., Schmidt, M., and Gunn, J.E., 1994, AJ, in the quasar evolution later (at higher redshift) and 107, 1245 stronger than found in previous work. Deeper [5] Croom, S.M., Smith, R.J., Boyle, B.J., Shanks, T., Miller, observations in this area may help to determine the L., Outram, P.J., & Loaring, N.S. 2004, MNRAS, 349, 1397 reality of this peak, quantify its amplitude, and better [6] Richards, G.T., and SDSS collaboration, 2006, in press constrain its redshift. Although 2dF has now been [7] Stern, D., et al. 2000, ApJ, 533, L75 decommissioned, it has regained a second life as the [8] Romani, R.W., et al. 2004, ApJ, 610, L9

ANGLO-AUSTRALIAN OBSERVATORY page 10 NEWSLETTER FEBRUARY 2006 END OF AN ERA: THE 6DF GALAXY (a)

SURVEY TAKES ITS FINAL HIGHLIGHTS SCIENCE SPECTRUM Heath Jones and the 6dFGS Team

Observing for the 6dF Galaxy Survey (6dFGS) finished on the 5th of January this year after nearly five years of collecting spectra on the UK Schmidt Telescope. This ambitious programme seeks the redshifts of 150000 southern galaxies and the peculiar motions for around 10000 of the brightest. Being a public survey, the redshift and spectral data for some 90000 sources have been made available in prior data releases in 2002, 2004 and 2005. Accessing the data is possible through an online database maintained by the Wide Field Astronomy group at the Royal Observatory Edinburgh (http://www- (b) wfau.roe.ac.uk/6dFGS/). The final instalment of data will be released later in 2006.

The key science drivers for 6dFGS seek the total stellar mass of the local universe and its relationship to environment and bulk flow motions. To this end, the main survey targets were selected from the Two Micron All Sky Survey (2MASS). Such near-infrared selection not Figure 1. (a) Close-up view of a portion of unreduced only furnishes a source list of the most evolved stellar spectra showing [OIII] and Hβ features in a bright emission- line source at z=0.00247. Astigmatism at the field edge populations, but also provides a direct link to the causes the lines to de-focus slightly. (b) Same spectra, luminous mass of the system as contained in stars. now reduced, showing how the spread of light has produced false emission-lines in the adjacent spectrum above the This single feature is what sets 6dFGS apart from its emission-line source. optically selected counterparts such as the SDSS and 2dFGRS. towards the edges of the 6dF spectrograph means that strong emission-lines can spread and contaminate Meeting the survey goals has been a challenge for the adjacent spectra if sufficiently bright (Figure 1). As a 6dFGS, but it has been in the fortunate position of consequence, neighbouring spectra gain additional capitalising on lessons learned from forerunners such emission-line-like features that in some cases can as the FLAIR and 2dF surveys. Instrument design, confuse redshift identification. Tom has software tools survey strategy and software are just some of the areas to identify instances of this, which we will use to flag in which the 6dFGS has benefited in this way. potentially affected spectra in the database.

The Final Data Release for 6dFGS will necessarily be Figure 2 shows the map of 6dFGS field coverage as it more comprehensive than all its predecessors. Being stands at the end of the survey. It shows how the survey the last time we update the database, several months has essentially covered the entire southern sky. The of exhaustive scrutiny of the dataset will need to take original survey target was the completion of all 1595 place. Manual examination of questionable redshifts, fields by the end of July 2005. However, a slightly higher application of zero-velocity template shifts as well as than expected fibre breakage rate meant that the average heliocentric corrections, and manual cross-checking of number of useful fibres turned out closer to 100 than associated field book-keeping are just some of the tasks the 120 originally expected per field. Consequently, by that will be undertaken during this time. For the online mid-2005 the survey was 155 fields short of complete database itself, there are plans to broaden its content coverage, with many of these spring and summer fields as well as provide additional links to supplementary around 02 to 06 hrs in RA. Negotiations with the RAVE information about certain fields and the data they Project underway on the UK Schmidt Telescope led to contain. the acquisition of 49 nights after July 2005 by way of swap and purchase so that 6dFGS could meet its goals. Recent work by Tom Jarrett (IPAC/Caltech) has examined the issue of fibre cross talk, a difficult but Alas, Mother Nature was not kind to 6dFGS during the (thankfully) rare occurrence in 6dFGS data. Astigmatism spring of 2005, and cloudy skies wiped many of the

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 11 FEBRUARY 2006 SCIENCE HIGHLIGHTS SCIENCE

Figure 2. Equal area Aitoff projection of 6dFGS field coverage. Open circles denote all fields on the target list and filled circles denote those comprising the survey.

October and November 6dFGS nights out. What Figure 3 shows the K and bJ luminosity functions from remains, as Fig 2 shows, is virtually full coverage except Jones et al. (2006), from a larger set covering KHJbJrF. for some areas around the LMC and the pole. The central Luminosity function fits from a number of recent surveys band is the Zone of Avoidance which 6dFGS did not are also shown for comparison. By this juncture in the attempt to cover. The final number of fields observed survey, a little more than half the redshifts were in hand. was 1539, or 96.5% of the total. The actual fraction of The luminosity functions shown here improve on previous the survey sky area covered is higher, since many of 6dF measurements in a number of ways. First, the the unobserved fields overlap with observed fields. sample sizes are much larger than before – the K-band survey alone totals some 60000 galaxies. Second, the The paper that accompanied the First Data Release magnitudes used in K have been updated with the latest (Jones et al. 2004) describes the main attributes of the 2MASS total magnitudes, and no longer rely on our 6dF Galaxy Survey, including the instrument, target original total magnitudes, which were inferred from a selection and redshifting procedures. A comprehensive combination surface brightness and isophotal magnitude introduction to the online database is also given. The (see Jones et al. 2004). Furthermore, the b r Second Data Release paper (Jones et al. 2005) J F magnitudes are the re-calibrated SuperCOSMOS summarises the main features of this second public magnitudes from which plate-to-plate zero-point variation release and discusses limitations that current users of has been removed (see Jones et al. 2005). Third, we the data should be mindful of. A final data paper will have made field flow corrections to our line-of-sight coincide with the Final Data Release and will characterise velocities using software by J. P. Huchra, thereby the survey in its finished state, as well as provide removing the peculiar velocity component of each galaxy. luminosity functions and densities.

(a) (b)

Figure 3. Luminosity functions in K and bJ from the 6dFGS. Those from other recent surveys are also shown. Magnitude offsets for different passbands (where required) have been indicated in the key.

ANGLO-AUSTRALIAN OBSERVATORY page 12 NEWSLETTER FEBRUARY 2006 Finally, the Schechter fit has been convolved with the magnitude error distribution in each passband. SCIENCE HIGHLIGHTS SCIENCE Of particular interest in Figure 3 is the upturn in galaxy numbers at the bright-end, an effect that has been noted by several authors previously. This excess of luminous objects is due to the brightest cluster galaxies, which are produced by the special merger and accretion processes that come into effect in the high-density regime at the centre of cluster gravitational potentials. We examined the galaxies responsible for this upturn in some detail, to confirm that the effect was real and not some measurement artifact. Figure 4 shows example spectra from this luminous subset alongside 2MASS and SuperCOSMOS images. The imaging reveals that Figure 5. Integrated luminosity density for 6dFGS across bJrFJHK. Comparative values from other recent surveys are there are a number of close galaxy pairs in this sample. also shown. We have also reproduced the spectral energy While they are not close enough to have inflated distribution for a 12 Gyr-old stellar population from Bell et al. (2003). Details in the text. magnitudes due to image blending – 2MASS can individually identify sources 5 arcsec apart – it supports With the final 6dFGS photon captured, we celebrate the idea that many of these galaxies inhabit dense the closing of another chapter in the illustrious history environments. of the UK Schmidt Telescope. We are grateful for the Figure 5 shows the luminosity density – a sort of volume- talent and hard work of all Schmidt observers – past averaged spectral energy distribution (SED), obtained and present – whose contributions to the 6dFGS have by integrating over all five 6dFGS luminosity functions. helped in no small part to shape it into the excellent The 6dFGS values agree with most estimates, finding a dataset it has become. Our sincere thanks are extended K-band value at the lower end of recent results for this to Donna Burton, Paul Cass, Kristin Fiegert, Malcolm band. This is also the expectation of the SED for a 12 Hartley, Dionne James, Ken Russell, Fred Watson and Gyr-old stellar population with a 4 Gyr e-folding the late John Dawe. The legacy of the 6dFGS will be exponentially decreasing star formation rate (dashed the public availability of these data to general users, line, after Bell et al. 2003). Models with more rapidly until such time as a more sensitive survey with equivalent declining star formation rates (say 2 Gyr) can produce full-sky coverage pushes south of the equator. SEDs more luminous in K, but at the expense of More information on the 6dF Galaxy Survey can be found overestimating optical luminosities by factors of two or at our web site: http://www.aao.gov.au/local/www/6df/ . more. References:

(a) (b) Bell, E. F., et al., 2003, ApJS, 149, 289 Blanton, M. R., et al., 2005, ApJ, bK 631, 208

60" 89" Cole, S., et al., (2dFGRS team), bK 2001, MNRAS, 326, 255 Driver, S. P., et al., 2005, 60" 73" MNRAS, 360, 81 Eke, V. R., et al., 2005, MNRAS, 362, 1233 (c) (d) Jones, D. H., et al., 2004, MNRAS, 355, 747 Jones, D. H., et al., 2005, PASA, 22, 277 bK Jones, D. H., et al., 2006, bK MNRAS, submitted 60" 63" 60" 57" Kochanek, C. S., et al., 2001, ApJ, 560, 566 Loveday, J., et al., 1992, ApJ, 400, L43 Figure 4. Example spectra of the most luminous contributors to 6dFGS. Images Norberg, P., et al., (2dFGRS from 2MASS (K-band) and SuperCOSMOS (bJ-band) are also shown. In these, north is up, east is left, and the field size in arcsec indicated in each corner. team), 2002, MNRAS, 336, 907 Zucca, E., et al., 1997, A&A, 327, 477

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 13 FEBRUARY 2006 substantial fraction of the Galaxy, that includes radial THE RADIAL VELOCITY velocities, and is thus capable of filling this gap in size EXPERIMENT: A SURVEY TO OBSER and time between existing astrometric surveys and the EXPLORE THE DYNAMICAL AND GAIA mission, which is expected to provide a complete CHEMICAL EVOLUTION OF THE census of our Galaxy by the end of the next decade. MILKY WAY 1 With the magnitude limit of RAVE (I<12), the survey will

V The RAVE team

A primarily focus on stars in the extended solar

T neighbourhood out to distances of a few kpc. The main The Radial Velocity Experiment (RAVE) is an ambitious OR science goals are: spectroscopic survey of the southern hemisphere to

Y measure radial velocities and stellar atmosphere • Increasing kinematical and chemical database NEWS parameters (temperature, metallicity, surface gravity) of of Galactic stars by 2 orders of magnitude. up to one million stars using the 6dF multi-object spectrograph on the 1.2 m UK Schmidt Telescope of • Searching for unique chemical and kinematical the Anglo-Australian Observatory (AAO). RAVE will signatures of stellar streams in the halo, outer bulge provide a giant leap forward in our understanding of the and thick disk due to satellite accretion. Galaxy, providing a vast stellar kinematic database • Determining the dynamical influence of the larger than any other medium or high-resolution survey local spiral arms and inner bar. proposed for the next ten years. It is a multinational endeavour involving scientists from Australia, Canada, • Measuring the degree of ellipticity, warping France, Germany, Italy, the Netherlands, Slovenia, and lop-sidedness of the disk. Switzerland, the UK and the USA. The RAVE program started in April 2003 and so far has delivered over 80,000 • Obtaining the first non-local measurement of spectra in the Ca-triplet region (8410–8790 Å) for the surface density of the disk, including the local southern hemisphere stars in the magnitude range escape velocity and so the overall mass of the Milky 9

ANGLO-AUSTRALIAN OBSERVATORY page 14 NEWSLETTER FEBRUARY 2006 OBSER V A T OR Y NEWS

Fig. 1: Status of RAVE observations as of December 12th 2005 presented in equatorial coordinates. The color coding corresponds to the number of times a field has been visited (including re-observations for calibration purposes). Yellow corresponds to one, green to two, blue to three and red to four observations. So far over 80,000 spectra have been obtained.

RAVE may observe up to 1 million stars providing a the internal accuracy with DENIS I magnitude for unique sample to study the formation and evolution of ~18,000 stars in common with the 1st data release. the Galaxy. The bottom panel presents the distribution of DENIS I magnitudes for those stars. The two peaks in this Data processing and catalog validation distribution correspond to the faint and bright subset, respectively, as defined in the input catalog. The RAVE survey can reach the science goals stated above only by a very careful reduction of observed The zero point of our radial velocity solution is obtained spectra. The issues of optimal spectral extraction, from sky emission lines in the Calcium triplet region. scattered light within the spectrograph, reliable With our exposure time of 50 minutes and resolution of wavelength calibration and background subtraction need 9000, the signal to noise ratio in those lines enables us to be studied in detail in order to allow a determination to estimate the zero point with an accuracy of ~1 km/s. of accurate radial velocity and stellar atmosphere parameters, i.e. its temperature, metallicity, gravity etc. During the course of the project, the radial velocity So a dedicated IRAF pipeline for basic data reduction solution is checked for stability and zero point accuracy. has been developed and tested. Another dedicated IRAF- The stability is estimated with re-observation of a subset based pipeline is then used to calculate the values of of RAVE targets, while the zero point accuracy is radial velocity and stellar atmosphere parameters. It checked using external radial velocity data taken with involves the minimum distance techniques, together with other telescopes and derived from other surveys. Fig. 3 cross-correlation procedures (XCSAO). The appropriate and Fig. 4 present a summary for the first data release. template is chosen from a set of ~20,000 synthetic In both cases, the agreement between RAVE radial spectra (~60,000 for the second year data) selected velocities and external or re-observed sources is in from Munari et al. (2005) and Zwitter et al. (2004). The excellent agreement with our expected uncertainties. main result is determination of the radial velocity to a We thus estimate an average total uncertainty for the few km/s. The distribution of the radial velocity internal 1st data release to be ~3 km/s. This level of precision errors is given in Fig. 2. More specifically, 50% of the is more than enough for almost all studies of galactic 1st data release has radial velocity errors below 2 km/s, kinematics and dynamics. 87% below 3 km/s. The figure shows the variation of

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 15 FEBRUARY 2006 OBSER V A T OR Y NEWS

Fig. 2: Distribution of RAVE radial velocity error (internal) as a function of I magnitude for a subset of 18,000 stars of the first RAVE data release that were observed also by DENIS (top panel). Bottom : distribution of DENIS I magnitudes for the same sample. The double peak distribution is a property of the input catalog.

Fig. 3: Analysis of RAVE re-observations. This figure presents the variation around the mean RV for 428 RAVE targets (943 individual spectra). The mean variation is consistent with zero while the rms is compatible with our internal error estimate, showing a good stability of our reduction.

ANGLO-AUSTRALIAN OBSERVATORY page 16 NEWSLETTER FEBRUARY 2006 OBSER V A T OR Y NEWS

Fig. 4: Comparison of RAVE RVs with RVs obtained in other programs. Blue corresponds to calibration observations performed with ELODIE, red to the Geneva-Copenhagen data and green to calibration data taken with the ANU 2.3 m. The general agreement of the RVs is very good, showing no significant zero point offset.

First data release

The first data release of the RAVE project is scheduled motions are taken from Tycho-2 and UCAC. The median for February 2006. The catalog will be accessible from accuracy for the proper motion is ~5 mas/yr. Stellar the RAVE website (www.rave-survey.aip.de and its parameters and spectra are not included in this first mirrors), via the Virtual Observatory and from the VizieR release, but they will be an integral part of future data database @ CDS. This release will include radial releases. The fact that a typical noise per wavelength velocities for ~25,000 stars in 240 6dF fields. The catalog bin is around 2% of the signal at I=10, and 5% at I=12 also provides cross-identifications with the standard indicates that the capabilities of RAVE reach well beyond photometric catalogs USNO-B, DENIS, Tycho-2 and radial velocities. Actually, AAO is the birthplace of the 2MASS, giving accurate optical and near-infrared largest spectroscopic survey of stellar properties yet magnitudes for the sub-sample selection. Proper undertaken.

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 17 FEBRUARY 2006 MELBOURNE OBSERVATORY AND Vogel and Lohse at Potsdam observed the spectra of HIST THE GENESIS OF ASTROPHYSICS all stars brighter than magnitude 4.5 between –10° and IN AUSTRALIA 20° and developed their own classification scheme. This was then widely used by astronomers, as was Secchi’s OR Jenny Andropoulos & Wayne Orchiston (James Cook University) early scheme, but controversy continued to surround

Y the interpretation of the different spectra and this was

OF OF to blight future research programs, including those Out With the Old and in With the New tentative studies carried out in Australia. The second half of the nineteenth century witnessed ASTRONOMY Spectroscopic Astronomy at Melbourne the emergence of the “new astronomy”, astrophysics, Observatory which gradually replaced positional astronomy. Positional astronomy was descriptive and dealt with what Melbourne Observatory (Figure 1) was arguably celestial objects looked like, where they were located Australia’s foremost nineteenth century professional and how they moved, while astrophysics was dynamic observatory (see Haynes et al., 1996), and was and examined the origins, compositions and evolution established in 1863 following the closure of the Flagstaff of celestial bodies. Astrophysics flourished because it and Williamstown Observatories. Founding director at brought two invaluable new analytical tools to Melbourne Observatory (as at Williamstown) was the astronomy: the spectroscope and the photographic charismatic Robert Ellery. plate. In this paper we shall focus solely on the emergence of astronomical spectroscopy in Australia. Holding pride of place at Melbourne Observatory from 1869 was the 48 inch Great Melbourne Telescope At an international level, astronomical spectroscopy was (Figure 2), and soon after it became operational le Sueur born in 1814 when Munich’s Joseph Fraunhofer used a carried out spectroscopic observations of Eta Carina, tiny 2.5 cm telescope to view the spectra of Sirius. Nine publishing the following description in the Proceedings years later he examined Betelgeuse, Capella, Castor, of the Royal Society: Pollux, Procyon and Sirius with a 10 cm refractor, and noted the dark absorption lines that now bear his name “The spectrum of this star is crossed with bright lines (see Hearnshaw, 1986). Stellar spectroscopy then had … The most marked lines I make out to be, if not to wait forty years before there was further progress, coincident with, very near to C, D, b, F and the principal but when this did occur it involved astronomers from green nitrogen line. There are possibly other lines, but three different nations and two different continents. those mentioned are the only ones manageable. The yellow (or orange?) line in the star has not yet received During the early 1860s, Donati and Secchi in Italy, Airy sufficient attention; it is however very near D …; at and Huggins in England and Rutherfurd in New York all present it cannot be said whether the line may not be published papers on stellar spectra, marking what is slightly more refrangible than D … Owing to the faintness now recognized as the real start of astronomical of the spectrum no dark lines were made out; one in spectroscopy. Hearnshaw (1986: 55) remarks that “It is red is strongly suspected. (le Sueur, 1870: 245).” certainly remarkable that all these pioneers should have been working practically simultaneously and At that time Eta Carinae was – and indeed still is – one independently on similar problems.” of the most enigmatic stars in the entire sky, and we now know that it would hardly be the object of choice if Of the five astronomers, Rutherfurd – who was an amateur, just like Huggins – was the first to attempt to classify the spectra of stars into different groups. He identified three groups. Stars in the first group resembled the Sun, were all reddish or golden coloured, and had many lines and bands in their spectra. In the second group were white stars like Sirius, while the third group also contained white stars, but they displayed no absorption lines. Today it is easy to associate Rutherfurd’s groups with the MK system.

These initial attempts to classify stellar spectra were followed by others, and from the 1870s the ability to permanently preserve spectra on photographic plates Figure 1: Melbourne Observatory soon after its marked a new era in astronomical spectroscopy. In 1873 founding (Orchiston Collection)

ANGLO-AUSTRALIAN OBSERVATORY page 18 NEWSLETTER FEBRUARY 2006 stark contrast, Ellery reported a

spectrum with very faint Fraunhofer HIST lines in the blue, violet, orange and red. OR Despite the size of their collective

sample, all Ellery and Baracchi could Y do was describe the spectra they OF observed. What they could not do was

interpret the spectra in any meaningful ASTRONOMY way, and this merely reflected the confusing state of spectral classification at that time. In a sense, these two Melbourne astronomers Figure 2: The Great Melbourne Telescope (courtesy: RAS Library) launched their stellar spectroscopic careers at just the wrong moment, for one were launching a new research program in stellar had they waited a few short years they would have spectroscopy! It is little wonder that le Sueur made no had access to Wien’s Law. In 1893 Wilhelm Wien attempt to interpret the spectrum that he described. suggested that the wavelength at which the radiated energy reached a maximum is inversely proportional Yet this impasse did not dissuade Ellery from further to the absolute temperature of the radiator: “The spectroscopic forays and both he and his ultimate colour of a radiating body is thus a function of its successor, Pietro Baracchi, were to embark on these in surface temperature … [and] At a stroke, stellar the late 1880s. But in each instance they made use of the spectral classification became physically meaningful. Observatory’s 8 inch refractor (Figure 3) and a Maclean Stars of spectral class M appear to be ‘red’, K orange, direct-vision spectroscope, rather than the Great Melbourne G yellow, F creamy, A white and B and O blue-white, Telescope. Both surveys were completed by 1889 and with surface temperatures increasing from 3,000 K published in two papers in Monthly Notices of the Royal to 35,000 K.” (Hughes, 2005: 108; our italics). Astronomical Society (Ellery, 1889; Baracchi, 1889). The spectral studies undertaken by Ellery and In all, the two surveys involved two hundred stars, but only Baracchi were initially planned as forerunners to a nine of these were common to both surveys. Seventy-five more extensive survey to be carried out with the Great of the stars showed continuous spectra, and the Melbourne Telescope, but the afore-mentioned predominant colours were blue and green; violet was rarely interpretive problems, staff shortages, other observing seen. About forty of the remaining stars revealed spectra with some combination of very faint C, D, F and G Fraunhofer lines; many of these stars appeared to be white or yellow. The remaining eighty-five stars had Fraunhofer lines and bands in their spectra, and Ellery and Baracchi made most frequent mention of the F, G and C lines, but the E, b, H and D lines were sometimes referred to. It was also noted that Gamma Crucis, 20 Librae, Eta Sagittarii and Delta 2 Gruis had ‘flutings’ towards the red ends of their spectra.

Nine stars appeared in both surveys, but only three of these (Beta Lupi, Pi Scorpii and Delta 2 Gruis) yielded consistent results. Of the other six, Ellery neglected to include any data for Beta Centauri in his paper, while he and Baracchi described differing spectra in the case of the other stars. For instance, Baracchi assigned a continuous spectrum to Beta Scorpii, while Ellery identified faint Fraunhofer lines in the blue and violet. In the case of Alpha Pavonis, Baracchi described a spectrum with dark bands and lines, including a very thick dark band or groups of dark lines far in the violet, and with similar bands near the Fraunhofer line G Figure 3: The 8 inch refractor at Melbourne and a dark band or group of dark lines near the F line. In Observatory (Orchiston Collection).

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 19 FEBRUARY 2006 commitments with the large reflector, and the newly-

HIST adopted Astrographic Program all conspired to prevent these laudable plans from coming to fruition.

OR Other Australian Spectroscopic Studies

Y Between 1869 and 1871, le Sueur – and perhaps other

OF OF Melbourne Observatory staff members – also used the Figure 5: Alfred Barrett 48 in Great Melbourne Telescope to examine the Biggs (Orchiston spectrum of 30 Doradus in the LMC. The Great Collection). ASTRONOMY Melbourne Telescope has a fascinating history (e.g. see Perdrix, 1992), but Malin’s claim that “In research terms, its results were clearly disappointing.” (Haynes et al., 1996: 107) is typical of the prevailing view. The first author of this paper is currently carrying out doctoral research on the observational work accomplished with this astronomy (Orchiston, 1999), but because Russell’s instrument, and one of her areas of special interest will spectroscopic paper was ‘buried’ in a local non- be to document and evaluate the entire suite of astronomical journal it failed to reach an international spectroscopic observations made with the Great audience and its true importance was all but lost. Melbourne Telescope. Finally, it should be mentioned that as elsewhere in the Melbourne Observatory was not the only Australian world, amateur astronomers in Australia were quick to professional observatory to delve into astronomical familiarize themselves with new developments in spectroscopy during the second half of the nineteenth astrophysics. In Hobart, Tasmania’s foremost century. In 1881 Sydney Observatory director, Henry astronomer, Francis Abbott, sought to popularize Chamberlain Russell, subjected the Great Comet of that astronomy by publishing three booklets in 1878, 1878 year (C/1881 K1 Tebbutt) to spectroscopic scrutiny and and 1880, and all of these contained readable up-to- presented his findings in a paper published in the Journal date information about the emerging field of astrophysics and Proceedings of the Royal Society of New South (see Orchiston, 1992). Meanwhile, Tasmania’s second- Wales (Russell, 1881). This comet (Figure 4) made a ranked astronomer at this time, Alfred Barrett Biggs fortuitous appearance as both astronomical (Figure 5), was fascinated by the brilliant red sunsets of spectroscopy and astronomical photography were 1884 and subjected them to protracted spectroscopic beginning to play a crucial rôle in international analysis (Orchiston, 1985). He even went and published astronomy and it was possible to apply both of these a paper on these so-called “sky glows” in the Papers techniques to this comet. Consequently, it came to and Proceedings of the Royal Society of Tasmania occupy an important place in the history of cometary (Biggs, 1884). With the benefit of hindsight, we now know this impressive atmospheric phenomenon was associated with the spectacular eruption of Krakatoa in what was then the Dutch East Indies.

References

Baracchi, P., 1889. MNRAS, 49, 439. Biggs, A.B., 1884. Papers Proc. Roy. Soc. Tasm., 202. Ellery, R.L.J., 1889.. MNRAS, 50, 66. Haynes, R., Haynes, R., Malin, D., and McGee, D., 1996. Explorers of the Southern Sky. A History of Australian Astronomy. Cambridge University Press. Hearnshaw, J.B., 1986. The Analysis of Starlight. One Hundred and Fifty Years of Astronomical Spectroscopy. Cambridge University Press. Hughes, D.W., 2005. J. Astr. Hist. & Heritage, 8, 107. Le Sueur, A., 1870. Proc. Roy. Soc., 18, 245. Orchiston, W., 1985. Rec. Queen Victoria Museum, 89, 1. Orchiston, W., 1992. Vistas in Astron., 35, 315. Orchiston, W., 1999. Irish Astron. J., 26, 33. Perdrix, J.L., 1992. Austr. J. Astron., 4, 149. Figure 4: The Great Comet of 1881 Russell, H.C., 1881. J. Proc. Roy. Soc. NSW, 15, 81. (courtesy Chapin Library, Williams College).

ANGLO-AUSTRALIAN OBSERVATORY page 20 NEWSLETTER FEBRUARY 2006 AAOMEGA IS COMMISSIONED taken for 12 programs in a wide variety of setups and data-taking modes. Nod&shuffle and cross-beam Rob Sharp and Will Saunders for the switching have been successfully commissioned, and OBSER AAOmega team some test mini-shuffled data (nod&shuffle using all fibres) looks very promising. Although many loose ends remain AAOmega was commissioned in three runs in to be tidied up, AAOmega is now a working instrument. November, December and January. November marked first light for the new fibre feed, 39 m in total from the Instrument performance and sensitivity V A

refurbished 2dF top end down into Coude West on the T There were several areas where we were particularly fourth floor. Simply routing the snake-like fibre-optic OR concerned that the instrument live up to predictions. cable, encased in its armoured conduit, safely down

These were: Y the Coude mirror train, proved quite a feat for the NEWS indomitable day crew, who worked without (much) 1) Would the fibres, with their input buttons and complaint in the full and terrible knowledge of the wrath output slitlets, have the uniformity and quality required? of Kristin, John and the fibres team should anything happen to the fibres en route. 2) Would the light propagate through 39 m of fibre optics without significant focal ratio degradation? Once safely out of the telescope, the fibres entered Coude West and were removed from their protective 3) Would the spectrograph optics perform as transit torpedo to be mounted in the AAOmega slit designed, giving the required imaging quality and exchanger, and system tests began in earnest. For the uniformity (crucial for accurate sky subtraction and radial November run, the 2dF field plates were not fully velocities)? populated, with only enough fibres and guide bundles 4) Would the overall throughput yield the expected for testing purposes being mounted. 2dF had at this gains of a factor of 2–3 with respect to 2dF? time been through a major 10th birthday refit and upgrade, and there was much about the system that we needed The answers to all these questions look to be ‘yes’ (or to shake down. Additionally, a manufacturing defect in at least ‘probably’). The uniformity of the data is superb, an LN2 dewar meant that only the blue arm was in with fibre throughputs varying by about 10% both in operation for this first run. The run was a great success absolute terms and spectrophotometric variations. The – integrating a system as complex as AAOmega with figure on the back cover illustrates this – it is 2 hours of the telescope control and support astronomer is a major co-added raw, low-resolution red data on faint targets – task and is one which requires AAOmega to be actually 350 simultaneous, long-slit-quality spectra. on the telescope and observing in order to complete. Test driving the control software, and confirming the The point spread function is remarkably Gaussian. It is astrometric accuracy of a number of 2dF top-end related extremely stable across the CCDs – varying in width by upgrades progressed well and the blue camera achieved only a few percent for a given wavelength (as required first light on a field of astrometric Tycho-2 stars. These for 1% sky subtraction). The blue camera gives images observations may represent some of the least interesting that meet or exceed specification (3–3.25 pixel FWHM). spectra to be taken with the AAOmega system during The red camera focus is less sharp (3.2–3.5 pixel FWHM, what is hoped to be a long and illustrious career. though still constant); there are known imperfections in the red camera alignment which will be rectified before For the second commissioning run in December, both routine science observations begin in late February. arms of the spectrograph were operational and the field plates fully populated with their 800 fibres (all 32 km- The red arm throughput looks to be 75–80% of the worth). While the first run focused on engineering and predicted value. This is despite a telescope primary instrument control, the second run focused on multi- mirror that has not been cleaned for a year or aluminised wavelength and multi-resolution observations of real for 2 years (re-aluminising will occur mid-February), and science targets. High resolution radial velocity data was some pupil misalignment in the spectrograph. So we taken, to investigate what will be achievable in the future. are confident that the red arm will live up to throughput Data was also taken for a number of fields from the expectations. 2SLAQ survey, to provide comparison data on faint LRGs For the blue arm, the throughput is still unknown. The and quasars. field lens in the camera remains frosted (from assembly As we go to press, the third and final commissioning in a hot and humid Sydney), and the moisture has proved run and the subsequent Science Verification stubborn to remove. A baffle accidentally both anodised observations have just been completed. Data has been and painted (hence trapping large amounts of moisture)

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 21 FEBRUARY 2006 is strongly suspected to be the cause of the problem. OBSER The amount of light lost to this frost – judging from its reflectivity and the scattered light on the detector – is

V clearly large, and we cannot A estimate a reliable T

OR throughput at this stage. A strip-down of the blue

Y camera is programmed NEWS before the first routine science observations in late February. The blue CCD is also less good cosmetically than the red one, with several bad columns near the middle of the detector which must be interpolated Figure 1: An r=20.23 galaxy spectrum at low resolution over. Data reduction Sky subtraction accuracy, using the traditional dedicated An essential part of the success of 2dF was the sky fibre technique will be crucial to many AAOmega availability of a fast, automated reduction package projects, particularly at longer wavelengths. Preliminary allowing observers to leave the telescope with fully extractions show sky subtraction often (but not always) reduced data under their belt. For AAOmega, we require better than a few percent and sometimes 1%. With reductions of equal robustness, but with a much higher improvements to the calibration system and data level of precision to do justice to the data. As we go to reduction software in the coming months, we hope to press, work on upgrading 2dfdr to AAOmegadr is reach 1% consistently. This would mean that many underway. Basic reductions are now straightforward, programs will not have to resort to nod&shuffle though some workarounds remain necessary at this techniques, which have significant efficiency overheads stage. Further improvements and tuning will be compared to dedicated sky-fibres. implemented as we gather more experience with the instrument.

Figure 2: An r=22.03 galaxy observed with nod and shuffle in two hours

ANGLO-AUSTRALIAN OBSERVATORY page 22 NEWSLETTER FEBRUARY 2006 OBSER V A T OR Y NEWS

Figure 3: High resolution R=10 000 spectrum of a K=10.77 star in the calcium triplet region with S/N>100, revealing a wealth of absorption lines as well as the obvious calcium triplet features.

Figure 4: An r=19.86 galaxy with [OII] emission at z=0.37 as observed by the blue AAOmega camera with the 580V grating.

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 23 FEBRUARY 2006 Sample data A NEW FIELD CONFIGURATION ALGORITHM FOR AAOMEGA

OBSER Here we show some commissioning data showing what AAOmega is capable of in its various setups and modes. Brent Miszalski (Macquarie), Keith Shortridge (AAO), Will Saunders (AAO), Figure 1 shows an r=20.23 spectrum from the raw data Quentin Parker (AAO/Macquarie) and shown above. The sky subtraction accuracy is about Scott Croom (AAO) V 2%; we are still working on improving this accuracy down A to the target of 1%. Such an accuracy would render T Introduction

OR nod&shuffle unnecessary for most programs (it is 2–8 times less efficient than observations with dedicated The complexity of multi-object spectroscopy (MOS)

Y sky fibres). instruments such as 2dF has tended to divert attention NEWS from some aspects of the observation process. Perhaps For the deepest data, nod&shuffle will still be needed, the most important area that has not been fully explored to achieve Poisson-limited sky subtraction. Figure 2 is the field configuration algorithm (FCA) used to select shows an r=22.03 nod&shuffle spectrum representing targets for observation. The FCA is primarily responsible just 2 hours ON + 2 hours OFF data. for allocating as many targets as possible, thereby maintaining the multiplex advantage of the instrument. Figure 3 shows high resolution Calcium triplet data for However, there are other more subtle FCA issues, such a reddened K=10.77 star, with S/N>100 and resolution as target sampling, which must be as uniform as R=10,000, revealing a wealth of lines for abundance possible. In some cases an FCA, by its inherent design, studies and promising sub-km/s radial velocity can imprint artificial power or bias onto observed target accuracy. distributions selected by the FCA. Such subtle biases Figure 4 shows an r=19.86 galaxy with [OII] emission can be detrimental to statistical analyses applied to at z=0.37 as observed by the blue AAOmega camera large-scale astronomical surveys that attempt to with the 580V grating (2.5 hrs exposure). In this plot produce a fair representation of large-scale structure in we have zoomed in on the interesting region of the the Universe. spectrum (the actual spectrum extends from 370nm to The advent of the AAOmega spectrograph for 2dF has 580nm) and show the plotting interface within 2dfdr. motivated an investigation into current FCA strategies SPIRAL IFU and alternative methods within the stable and mature development environment of 2dF CONFIGURE. The As well as feeds from the two 2dF field plates, AAOmega default ‘Oxford’ algorithm for CONFIGURE was designed will also support integral field observations with a specifically for the 2dF Galaxy Redshift Survey refurbished SPIRAL IFU mounted at Cass. The SPIRAL (2dFGRS; see §5.1 of Colless et al. 2001) to achieve system will be available with any AAOmega grating high target yield for fields with a similar number of targets configuration, and will give 50% higher spectral resolution and fibres. Indeed, the ‘Oxford’ algorithm achieved its because of its smaller fibres. SPIRAL has a field of view task with acclaim, contributing to the success of the of 22x11 arcsec. SPIRAL IFU mode is due for 2dFGRS. commissioning in June 2006. Despite its heavy usage during the lifetime of 2dF, it is This article is dedicated to Terry Bridges, for his only recently that sufficiently sensitive measurements dedicated work as project scientist in the design stages, of the sampling behaviour of the ‘Oxford’ algorithm have and also for the wonderful and sadly missed bottle of been made by Outram (2004) and Miszalski (2005). whisky he left with us to celebrate first light. These tests have revealed that the fundamental design of the ‘Oxford’ algorithm does not satisfactorily deal with the higher density, multiple-priority fields anticipated to be the staple diet of AAOmega.

Here we present an overview of a newly developed FCA based on simulated annealing (SA) that is currently being integrated into 2dF CONFIGURE. It addresses all the major shortcomings of previous FCAs and provides support for new observational modes available with AAOmega. It is planned to become the default FCA for AAOmega observations. The generic nature of the

ANGLO-AUSTRALIAN OBSERVATORY page 24 NEWSLETTER FEBRUARY 2006 algorithm means that it can be used for 6dF fields, and The optimality criteria ensure that the multiplex is suitable for VLT FLAMES, Subaru FMOS and future advantage of the instrument is maintained, that target

MOS instruments. Further details are presented in priorities are weighted correctly, that minimal artificial OBSER Miszalski (2005) and Miszalski et al. (2006, in prep). power is imprinted on target distributions, and that different sky subtraction techniques and a large variety Algorithm Overview of fields are supported. These criteria are not mutually exclusive. For instance, it would be undesirable to SA is a generic method of solving constrained V

allocate sky targets at the expense of high priority targets A optimisation problems, developed by Kirkpatrick et al. when low priority targets remain allocated. T

(1983). SA employs the probabilistic Metropolis OR algorithm (Metropolis et al. 1953) to simulate the thermal The randomisation process of the SA algorithm entails motion of a system (in this case a field) whilst slowly ~105 fibre swaps. Traditionally CONFIGURE spends a Y cooling the system to simulate the annealing process majority of its time re-calculating collisions between NEWS of physical systems. Many small, random perturbations fibres and buttons each time a new allocation is made. (fibre swaps) are made at each stage in the cooling We have developed a novel allocation sub-system that process (known as the annealing schedule). The pre-calculates all possible collisions within a field and perturbations explore the set of possible solutions (the stores them within a sparse, indexed collision matrix. parameter space) under the guidance of the Metropolis This has made the previously prohibitive amount of swaps algorithm that is designed to efficiently find near-optimal easily achievable – within minutes rather than hours! solutions. If slow cooling takes place then the solution The removal of this bottleneck has enabled the SA obtained may also be uniform, with progressively finer algorithm to explore much more of the parameter space structure being ‘ironed-out’ with decreasing temperature. of a field than previous FCAs to produce a more optimal SA has been successfully applied to problems similar solution. to field configuration, most notably the tiling of the 6dF Galaxy Survey (Campbell et al. 2004). Algorithm Advantages

We designed the new algorithm to satisfy the following The optimality criteria are largely satisfied by the optimality criteria: objective function of the SA algorithm. The objective function is a measure of the quality of the field • High overall yield independent of target priority. configuration, i.e. how optimal the configuration is. It is this quantity that the algorithm endeavours to maximise • Highest priority targets have highest possible to obtain the most optimal solution possible. It also yields. provides a simple yet powerful and flexible means to • Uniform sampling overall and for each priority. influence the final solution. Additional terms can be introduced to maximise such quantities as fibre • Observational flexibility.

Fig. 1: Gain in overall target yield of the SA algorithm over the ‘Oxford’ algorithm. The left panel shows the gain for fields extracted from mock 2dF catalogues (Cole et al. 1998) with moderate target clustering. The right panel shows the yields and gains (inset) obtained from generated Gaussian fields parameterised by sigma (lower sigma corresponds to higher central clustering).

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 25 FEBRUARY 2006 straightness or close pair yield. For simplicity we cover point correlation functions, completeness and target here the advantages of the SA algorithm rather than yields.

OBSER delve into the objective function and its implications. • Simplified algorithm maintenance via objective The new algorithm provides the following advantages function to allow future support of specialised over the ‘Oxford’ algorithm: observational requirements.

V • Increase in overall target yield by up to 11% Algorithm Limitations

A (~5% for typical fields) (Fig. 1).

T The advantages leave few limitations that can be OR • Increase in target yield of highest priority associated with the new algorithm. Such performance targets by up to 30% (Fig. 2). does entail a time penalty, but this is not necessarily Y problematic. NEWS • Much more uniform sampling of targets and removal of the panoply of artificial structures The most significant of these penalties is the calculation imprinted by the ‘Oxford’ algorithm at high target of the collision matrix that allows for orders of magnitude densities (e.g. Fig. 3). greater fibre swaps than previous algorithms. This in turn allows more optimal solutions to be found than were • Removal of previously unforeseen artificial hitherto possible. Fig. 6 shows actual calculation times structure in different priority distributions (Fig. 4). for fields with uniformly distributed targets, in addition • Effective allocation of sky targets by to fields with moderately clustered targets from mock reassigning fibres from lowest priority targets (Fig. 2). 2dF catalogues. The data show that on average it takes ~5 minutes to set up the collision matrix on a reasonably • Support for nod&shuffle with Cross-Beam powerful desktop computer. Switching (Saunders 2005) with at least 98 pairs allocated under difficult circumstances (Fig. 5). Further limitations to the collision matrix setup include an intolerance of fields with very high target numbers or • Ability to weight close target pairs of given heavily clustered targets. Such fields may be handled separation. provided that sufficient physical memory is available (~2GB recommended). However, such fields may involve • Well documented implementation with lengthy collision matrix setup times of ~30–60 minutes. characterised sampling statistics in terms of two-

Fig. 2: Average priority distributions for fields with 100 targets of each priority configured by the ‘Oxford’ (left column) and SA (right column) algorithms. The handling of target priorities by the SA algorithm produces a very optimal priority distribution with and without sky targets allocated. The ‘infiltration’ of low priority targets in the ‘Oxford’ algorithm (top) is further compounded by the poor redistribution of fibres to sky targets (bottom).

ANGLO-AUSTRALIAN OBSERVATORY page 26 NEWSLETTER FEBRUARY 2006 OBSER

Fig. 3: Completeness C(x,y) (fraction of allocated targets) as a function of field plate position for fields with uniformly distributed

targets (number as indicated) configured by V

the ‘Oxford’ (top) and SA (bottom) algorithms. A The SA algorithm eliminates all of the artificial structure imprinted by the ‘Oxford’ T algorithm at high target densities save for OR only a slight gradient present in the radial

direction. Y NEWS

For these fields a reduction in field complexity is required controlled. Fortunately, we plan to provide the user with to reduce collision matrix setup times to acceptable at least three presets of thorough, intermediate and quick values. This is not to say that this will be the norm for configuration speeds. More detail on these settings will most users; indeed the vast majority of fields configured be provided in revised CONFIGURE documentation. during algorithm development were accommodated by modest computer specifications. Fortunately, the collision matrix is reusable and once calculated it will be stored as a binary ‘.matrix’ file (typical The actual algorithm runtime is not so easily size ~50–100MB). This enables the user to reconfigure benchmarked as the collision matrix setup time, a field with different algorithm parameters as many times primarily because of the large number of variables as desired until either an optimal solution is found or involved. The default runtime of the annealing schedule the field changes (either field centre changes or targets (the heart of the algorithm) is typically ~5 minutes, are changed). The latter requires that the matrix be roughly the same time as the collision matrix setup recalculated before configuration can recommence. The time. This is highly dependent on the amount of inclusion of sky targets is therefore recommended clustering in a field and specific algorithm parameters before the collision matrix is established. All the that determine the number of fibre swaps made at each aforementioned limitations classify the algorithm as temperature decrement, the latter of which can also be semi-interactive. Indeed, the algorithm generates

Fig. 4: Radial completeness C(r) (C(x,y) averaged over theta) for fields with 200 P9, 200 P8, 100 P7 and 100 P6 uniformly distributed targets configured by the ‘Oxford’ (left) and SA (right) algorithms. The SA algorithm completely removes the panoply of previously unknown structure imprinted on lower priority targets.

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 27 FEBRUARY 2006 2006.

Acknowledgements OBSER

BM acknowledges an AAO/Macquarie Honours scholarship that enabled this work. The authors wish to thank P.J.

V Outram for his foresight and assistance. A

T References OR Campbell, L., Saunders, W., Colless, M.

Y 2004, MNRAS, 350, 1467

NEWS Cole, S., Hatton, S., Weinberg, D. H., Frenk, C. S. 1998, MNRAS, 300, 945 Donnelly, R. H., Brodie, J. P., Allen, S. L. 1992, PASP, 104, 752 Kirkpatrick, S., Gelatt, C. D., Vecchi, M. P. 1983, Science, 220, 671 Metropolis, N., Rosenbluth, A., Rosenbluth, M., Teller, A., Teller, E. Fig. 5: Average number of allocated pairs from fields with 400 uniformly 1953, Journal of Chemical Physics, distributed target pairs with a variety of separations and orientations. The SA 21, 1087 algorithm (filled circles) consistently outperforms the ‘Oxford’ algorithm (open Miszalski, B. 2005, Honours Thesis, circles) by 33%. At least 98 pairs are allocated in all cases, meeting the limit Macquarie University of observable target pairs – a constraint imposed by the AAOmega CCD Miszalski, B., et al. (2006, in prep) area. Outram, P.J. 2004, http://www.aao.gov.au/ local/www/brent/configure Saunders, W. 2005, AAO Newsletter, sufficiently optimal solutions that batch mode Number 108, Page 8 field configuration is a viable alternative that may be utilised by tiling algorithms of upcoming AAOmega surveys.

Algorithm Status

The algorithm is currently implemented within a new batch version of CONFIGURE developed alongside the algorithm. It is currently being reworked back into the standard CONFIGURE. This work also involves the:

• Delegation of the old FCAs to ‘expert’ mode.

• Simplification of the new algorithm parameters.

• Collision matrix integration to be transparent to the user.

• Implementation of a histogram of priority yields and a plot of objective function with temperature to show optimality of Fig. 6: Time needed to setup the collision matrix before the actual FCA configured field. may configure a field. The main series with error bars are fields with NTargets uniformly distributed targets. Other data represent moderately There will be an updated CONFIGURE manual clustered fields from mock 2dF catalogues. Statistics obtained with a with sample fields and example runs of the 2.4 GHz P4 Xeon CPU. algorithm explained to help ease the transition. It is anticipated that the new version of CONFIGURE will be released before mid

ANGLO-AUSTRALIAN OBSERVATORY page 28 NEWSLETTER FEBRUARY 2006 detailed description of the accounting of the observing NOTES FROM AATAC time is available in the August 2005 AAO

Martin Asplund, AATAC chair (RSAA, ANU) Newsletter (p. 17). For the recent 06A round, this worked OBSER extremely well, with both AU and UK receiving almost The inaugural meeting of the Anglo-Australian Time exactly their actual share (imbalance relative to partner Allocation Committee (AATAC) was held at the AAO share <0.5 night). headquarters in Epping on November 2–3, 2005. Gone The oversubscription rate for 06A was a healthy 3.6 V now are the days when AU and UK astronomers would A submit proposals to separate TACs (ATAC and PATT; (bright time), 2.5 (grey) and 2.1 (dark). This semester T ATAC will however continue to handle AU applications was the first with a dedicated call for large programs OR for Gemini time). The institution of a new joint committee (>50 nights) with AATAC aiming to set aside >20% of the available time for large programs in future years. Y should improve the efficiency of the AAT as well as NEWS stimulate further scientific collaborations between the Although this new feature was instigated by the two countries. The new AATAC is very much looking upcoming availability of the new AAOmega spectrograph, forward to helping ensure that the AAT remains productive large programs can be proposed for any of the AAT facility and will continue to generate high-impact science. instruments (AAOmega, UCLES, UHRF, WFI and IRIS2). For 06A there were 11 proposals for large The format of AATAC is largely moulded on ATAC. It will programs. AATAC was very pleased with the large have seven members, currently four from AU and three number of such proposals presenting compelling science from UK; as the UK financial contribution to AAO will cases of the highest quality. Besides being extensively ramp down in the coming years, the membership of discussed within AATAC, these proposals were also AATAC will be reviewed annually by the AAT Board in externally reviewed. Each proposal was sent to three order to reflect the partner shares. The board has decided referees with expertise in the relevant field for that the AATAC chair will always be Australian while the assessment; the return rate for reports was quite high deputy chair will be British. The current membership is: (after some prodding and begging...) with all proposals receiving at least two referee reports. • Martin Asplund (chair, ANU), For 06A, AATAC decided to take a somewhat • Michael Drinkwater (Univ. of Queensland), conservative approach, only approving one such large • Seb Oliver (Univ. of Sussex), program, the Anglo-Australian Planet Search program (PI: Chris Tinney). The main reason for this is that • Sean Ryan (deputy chair, Univ. of Hertfordshire), AAOmega – the instrument most large programs proposed to use – had not yet been commissioned and • Peter Tuthill (Univ. of Sydney), its on-telescope efficiency therefore not accurately • Jacco van Loon (Keele Univ.) and known. Furthermore, many of the programs required pilot studies to demonstrate convincingly that the • Rachel Webster (Univ. of Melbourne). techniques and methods are appropriate before justifying allocating a large number of AAT nights. Individual The members of the service time sub-committee are feedback on each proposal has been distributed to the presently Peter Tuthill (AU representative), Sean Ryan PIs. Another call for large programs will be made in 06B (UK) and Antony Horton (AAO). In general, AATAC will and thereafter in each B semester. AATAC remains not rely on external referees to assess proposals but committed to the goal of awarding >20% (with no has the discretion to do so when the need arises, such predetermined upper limit) of the time on AAT to such as for large programs (more below) and for applications large projects. outside the scientific expertise of the various AATAC members. The application deadline will be March 15 Please do not hesitate to contact the chair (“B” semesters) and September 15 (“A” semesters). ([email protected]) or any of the other members if you have questions about AATAC and its work. We The allocation of observing time will roughly reflect the also appreciate feedback from the AU and UK partner shares. Naturally, this can not and should not communities, in particular now in the beginning as we be done exactly. Instead, the AAO Director has are still trying to decide on appropriate ways to operate suggested an allocation formula, which has and the policies for the new committee. For the interested subsequently been endorsed by the AAT Board and reader, the current version of the AATAC guidelines is adopted by AATAC. The formula is designed to stimulate available at: http://www.aao.gov.au/AAO/astro/apply/ continued collaboration between the two countries while aatacguidelines.v3.pdf being cognizant of the varying partner contributions; a

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 29 FEBRUARY 2006 AUSTRALIAN SUMMER STUDENTS 150 x 150 x 2048, and will be visualized using Karma FOR 2005/06 software developed for radio astronomy. Emission line Scott Croom widths, line kinematics and line ratios will be examined at each spectrum within the cube. If the jet picture is

LOCAL The Anglo-Australian Observatory runs a summer correct, the properties of the emission will be highly student program for undergraduates from both the UK complex over the full field, and this will be the first (during the northern summer) and Australia (during the evidence of a jet in this extraordinary source. southern summer). The current Australian students are Chris Banks is working with Rob Sharp and Tim Schmidt

NEWS Shane Hengst, from Macquarie University, Ryan Cooke (from the Physical Chemistry group at Sydney from Queensland University of Technology and Chris University) on the reduction and analysis of UCLES Banks from the University of Queensland. They are spectroscopy of the Red Rectangle nebula. working on a number of observational projects using data from the AAT and also the VLT. The Red Rectangle, one of the brightest sources in the mid-IR as seen by IRAS, is a proto-planetary nebula Shane Hengst is working with Heath Jones on deep on/ with some unusual spectral properties. The spectrum off-band narrowband imaging of 20 low-redshift (z ~ 0.3 exhibits unidentified molecular band emission at a wide and 0.45) QSOs. The 20 QSOs are drawn from the range of wavelengths, much of which is commonly optically-selected Calan-Tololo QSO Survey of J. Maza claimed to be due to emission from Polycyclic Aromatic and collaborators. The imaging was obtained with FORS2 Hydrocarbon molecules (PAHs). Identifying the carriers on the ESO VLT and is being put to two uses. The first of these bands will require detailed laboratory is to reveal the possible existence of extended nebular spectroscopy, which is in progress in the Sydney Laser line emission on 10 to 100 kpc scales in the vicinity of labs. However, accurate astronomical spectra are the QSO. The second purpose is to locate emission- required to compare to the laboratory data. line galaxies at the same redshift as the QSO and whose presence would indicate clustering in the QSO The unusual environment of the nebula complicates the environment. One would expect to see a connection structure of the molecular emission bands. High between these two phenomena if cluster cooling flows resolution, spatial resolved spectroscopy of the nebula are indeed the mechanism responsible for extended is required to disentangle the emission structure. Our QSO emission. Supporting broad band imaging provides UCLES data was taken in support of Integral Field a ready discriminant between foreground and background observations obtained with the ARGUS IFU on the VLT emission lines. (through the allocation of two nights of guaranteed time from delivery of the Oz-Poz instrument by the AAO). This observational project marks a change from the While UCLES provides only the one spatial dimension theoretical work that Shane has done previously. His with its 8 arcsecond long slit, the extended wavelength 2005 Honours thesis at Macquarie University modelled coverage provided is the complementary information we dust grains in different turbulent structures, require to interpret the ARGUS spectra. encapsulating the dynamics of the dust grains in proto- planetary discs. Weather was not kind during the observing run. However, in a single night UCLES was able to record Ryan Cooke is working with Joss Bland-Hawthorn on almost complete wavelength coverage from 4000–8000Å new data taken with the VLT VIMOS IFU. The and at a resolution of R~40,000, covering most of the observations are of an emission line nebula that molecular emission features we wish to cross-reference surrounds the x-ray binary source LMC X-1. These with the limited wavelength coverage IFU data. The task observations were inspired by a TTF H-alpha image of of reducing the long slit echelle spectra is one which the source that appears to show streamers possibly Chris is currently taking in his stride. Once the data is arising from a jet flow. A new Spitzer mid-infrared image reduced Chris will determine the wavelength and band- reveals that the emission line nebula sits within a “hole” widths for a range of molecular emission features seen in the dust distribution which may support the idea of a in the data. wind-blown cavity. The new spectroscopic data cubes should tell us whether the streamers arise from a jet impacting on the inside of a dusty cloud.

The VIMOS IFU obtained a total of 4 hours of data on the source in four contiguous fields. These data are being reduced with the recently released VIMOS reduction pipeline software. The final data cube will have dimensions

ANGLO-AUSTRALIAN OBSERVATORY page 30 NEWSLETTER FEBRUARY 2006 LETTER FROM COONABARABRAN EPPING NEWS Rhonda Martin Sandra Ricketts

Wishing our lives away, we look pantingly forward to There have been quite a number of comings and goings the autumn when it will be, hopefully, cooler and we can since the last newsletter, spread over a couple of LOCAL NEWS gain relief from the breathtaking, mind-numbing heat that generations. has plagued us of late. Alternatively, we can eagerly check the schedule for Paul Butler’s next visit – it The previous writer of this column, Greta Simms, left us ALWAYS rains when Paul makes a visit. Usually at towards the end of last year, after 10 years at the AAO. Coona we can cope with the heat because the nights She was farewelled at a barbecue at Epping in November. are cool, but lately ………… My goodness, it’s like We are pleased to have Carolyn Hampele back again living on the coast. Without any rain since early to make sure we are all paid! Pat Roche returned to the December lawns are crunchy and leaves hang limply, UK in December after his sabbatical at the AAO, and so – we await Paul. John Storey also returned to UNSW after his half-time sabbatical It doesn’t help, of course, to have Frank Freeman extolling the wonders of retirement and sending pictures We welcomed Simon O’Toole who will be working on of white beaches and big fish. AAO Planet Search data, as well as Antony Horton and Mike Birchall who will both be working with the software But then – the project that has driven us for what seems group. Antony will be working on TCS and Mike on the forever, has made staff bleary-eyed and short of temper, FMOS DR project. We hope they enjoy their time at has taxed ingenuity to the edge of brilliance and been a the AAO. bit of a windfall for fibres manufacturers – AAOmega, arrived at Site along with a horde of Epping staff. I Congratulations are due to both Chris Tinney and Scott remember Greg Smith complaining about the cold. Croom on the births of Nicholas William Tinney and Cold? What cold? The old Mappitt room is now the Samuel William Scott Croom in November. The AAO AAOmega room and very smart it looks too. But the seems to be having another baby boom! great thing is, it works! There are glitches, of course, but these are being ironed out at a rate of knots. LIBRARY NEWS It’s all gone rather quiet now – the long tables have Sandra Ricketts been removed from the walkway, the fibres lab is no longer frenetically busy or full of people helping get the Life in the AAO library continues much as usual. Towards fibres all together, the 4th Floor is tidy again (more or the end of last year library users were asked to respond less) and we have toasted a job well done with whisky, to a survey on their use of the library. Various useful wine and water (not all together). Congratulations are suggestions were made, and by and large people saw due to a lot of tired people taking a well-earned rest. the future of the library as being a mixture of physical Site is also host to John Danson, a local lad studying and virtual resources. It is hoped that the various electrical engineering at ADFA. He will be with the suggestions can be acted upon this year. electronics people for the next six weeks or so. Some changes have been made in the library at the telescope – there is a new computer (newer and faster even than the one this newsletter is being produced on!), as well as a new scanner and printer. Some rearrangement of furniture has also taken place. It is hoped that this equipment will be used more by library users at the AAT – it is not for the exclusive use of the librarian by any means!

Don't forget that the major astronomy journals are no longer received in hard copy at the telescope, but of course are available on-line – use the new PC (and printer if necessary). Older issues are still on the shelves in various places – the library itself, the corridor outside, Frank Freeman working hard in retirement! and study 4.

ANGLO-AUSTRALIAN OBSERVATORY NEWSLETTER page 31 FEBRUARY 2006 .au > .au > .aao.gov p AAOmega (2 hours coadded) hours (2 AAOmega a at low resolution low at a @aaoep @aaocbn.aao.gov user < user <

Y a from the red arm of arm red the from a OR VAT 6884 2298 email 2 AAOmega dat AAOmega Australia

Fax +61 2 9372 4880 email 4880 9372 2 +61 Fax 1710 Raw .au > Raw low-resolution dat low-resolution Raw editorial assistant SANDRA RICKETTS SANDRA assistant editorial 4800 .aao.gov 6842 6291 Fax +61 2 ANGLO-AUSTRALIAN OBSER t SCOTT CROOM < http://www < T/Schmid elephone +61 2 9372 elephone +61 Published by editor ISSN 0728-5833 PO Box 296 Epping, NSW Epping, 296 Box PO Epping Lab T T AA URL

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