Telescopes and Instrumentation

The VLT Survey Telescope Opens to the Sky: History of a Commissioning

Massimo Capaccioli1,2 mirror, and an alt-azimuthal mounting. Its Pietro Schipani2 single focal plane instrument, ­OmegaCAM, is a large format (16k × 16k pixels) CCD

camera contributed by the OmegaCAM ESO/G. Lombardi 1 Department of Physical Sciences, consortium (see Kuijken, p. 8). ­University Federico II, Naples, Italy 2 INAF–Capodimonte Astronomical The VST is the result of a joint venture Observatory, Naples, Italy between ESO and the Capodimonte Astronomical Observatory (OAC) in Naples, formerly an independent institu- Commissioning team members: tion, and, since 2002, part of the Italian 1 1 1 Massimo Dall’Ora , Sergio D’Orsi , Laurent Marty , National Institute for Astrophysics (INAF). Carmelo Arcidiacono2,3,5, Javier Argomedo3,4, Jacopo Farinato5, Demetrio Magrin5, Roberto It is the largest instrumental project ­Ragazzoni5, Gabriele Umbriaco6 ­carried out by Italian astronomy for ESO and the first active optics telescope ­completely designed in Italy, from 1 INAF–Capodimonte Astronomical Observatory, Italy, 2 INAF–Bologna Astronomical Observatory, scratch, and by a fistful of engineers. Italy, 3 INAF–Arcetri Astronomical Observatory, Italy, 4 ESO, 5 INAF–Padua Astronomical Observatory, Here we briefly describe the final stages 6 Italy, University of Padua, Italy of the project before its completion and report on the scientific programmes devised by the INAF community for the The VLT Survey Telescope (VST) is now guaranteed time observing (GTO). For the ready to undertake its mission. After a earlier history see Capaccioli et al. (2003, long gestation, the telescope has re­­ 2005). Figure 1. A view of the VST inside its enclosure, sur- vealed its power, providing image qual- rounded by the electrical control cabinets. UT4 and the Atacama desert are visible in the background. ity and resolution beyond expectation. This achievement has been made pos- Early development sible by a motivated team of scientists to be calculated at the net of the Chilean and engineers who have brought the The VST project was proposed by OAC time). These numbers reflect the effort VST to its current state of readiness for to ESO in 1997 and began in 1998 made by INAF to boost the ESO Public survey science. This paper briefly with the signature of a Memorandum of Surveys, and take into account the delays reviews the latest stages of the project Understanding (MoU) establishing the in the project. INAF was also granted and the characteristics of the VST, dues and rights of the partners. OAC a number of hours, equivalent to 28 nights and lists the scientific programmes for committed to procuring the telescope at one VLT UT, to be evenly distributed the observing time guaranteed by and providing up to two of its personnel over an interval of ten years and to ESO to the Italian community in return to support the operation of the facility. be used exclusively for follow-up pro- for the procurement of the telescope. In return, OAC (now part of INAF) was grammes for INAF–VST surveys. entitled to receive a proportional share of the total VST observing time plus a num- The development of the project was Introduction ber of nights at one VLT Unit Telescope marked by two major accidents which (UT). ESO committed itself to provide have extended the schedule signifi- The VLT Survey Telescope (VST) is a the facilities needed to house and run the cantly: the first back in 2002, when the wide-field optical imaging telescope with telescope at Paranal, to cooperate with primary mirror (M1) was literally shat- a 2.61-metre aperture, operating from the OAC in setting the specifications and tered during its transfer by ship to Chile. ultraviolet to the near-infrared (z’-band) interfaces of the telescope, to procure Recovery from this took almost four with a corrected field of view of 1 degree the transport of the instrument from Italy years, while the Russian firm LZOS, by 1 degree. Views of the VST in its dome to Chile, to secure the proper CCD cam- which had very successfully manufac- are shown in Figures 1, 2 and 3. Con- era, and to commission the complete tured the first mirror, completed an exact ceived for the superb environment of the VST system. Moreover ESO took respon- replica. In addition to the time delay, it Paranal Observatory (Figure 4), it fea- sibility for the operation and maintenance had grave collateral effects on the moti- tures an f/5.5 modified Ritchey–Chretien of the VST for a period of ten years. vation of the VST technology team at optical layout, a two-lens wide-field cor- OAC and on the budget (see Capaccioli rector with the dewar window acting as a In the summer of 2011 ESO and INAF et al., [2005], for more details). third lens or, alternatively, an atmospheric amended the MoU and agreed on the fol- dispersion compensator coupled with lowing share for the INAF–GTO: 10% In 2002 the Italian observatories were a single-lens wide-field corrector plus the for the first four years of the telescope’s merged into the National Institute for dewar window, an active primary mirror life, 15% for following two years, and 20% Astrophysics, which had the critical mass (Figure 5), a hexapod-driven secondary for the remaining four years (percentages to sustain OAC in this dramatic phase of

2 The Messenger 146 – December 2011 ESO/G. Lombardi ESO/G. Lombardi

Figure 2. The VST from above. The M1 cover is open which should have given the green light Figure 3. The VST as seen from the observing floor. and the primary mirror is visible with its baffle. On to these crucial units, was globally The OmegaCAM instrument and its control cabinets top, the back side of the hexapod driving M2 is visi- are in the lower section, interfaced to the telescope ble. The observation doors with the wind screen are unsuccessful. Of course, the immediate at the Cassegrain focus. seen on the right side of the picture. feeling at OAC was of considerable dis- appointment! But looking back, this fail- ure marked the turning point for the later concept of the primary mirror support the project. In addition to money, INAF success. The key problem identified by and safety system redesigned, with provided managerial and technological the ESO reviewers was a lack of proper regard to performance, reliability, and support using the knowhow available systems engineering in the project, which maintenance operations. The error in its other structures, increasing the had been diluted by the ­considerable budget was modified, adopting ambi- staff complement by bringing in people, efforts made on the single subsystems. tious, but realistic, capabilities for the mainly from the Padua Observatory. In ­telescope subsystems. Two major simpli­ late 2005 INAF also created an ad hoc fications were introduced into the active institute, based at Capodimonte and Recent progress optics subsystems. The 24 lateral active named VSTceN, to coordinate the pro- supports in the M1 cell were replaced ject, which was placed under the direc- Starting from mid-2007, the primary and by passive astatic levers, and three lateral tion of Massimo Capaccioli, former OAC secondary mirror support systems were fixed points were introduced. In addition, director and the principal investigator of extensively reconsidered by INAF–OAC the piezoelectric plate, with five degrees the VST. at the systems engineering level, trans­ of freedom, coupled to the hexapod for ferring the technical leadership to P. the accurate positioning of the secondary By March 2006 the new primary mirror, Schipani and establishing a new team mirror (M2) was eliminated, with no real with which the active optics sub units with some of the engineers who had loss of accuracy and a major gain in relia- had to be carefully matched, had safely already been working on the project. The bility and operability. reached the Paranal Observatory, and re-design of the active optics system by the end of the year an ESO audit team was further complicated by two stringent The primary mirror support system spent about one month with the OAC conditions: to minimise the changes design, the control software and the team in Naples and concluded that the and the expenditures and to close out the electronics were updated by INAF–OAC, telescope mount and the tracking sys- activities as soon as possible. and the new mechanical parts were tem, pre-assembled at the MecSud firm designed by Tomelleri srl, the firm which in Scafati, were ready for shipping to This strategy led to success: in a little also re-cabled the cell, under VSTceN Chile, which was done during 2007. The less than two years, including manufac- requirements and supervision. The earth- telescope was then re-integrated and turing and tests, all the parts of the quake safety system, previously over- tested at Paranal. In the same year, the ­telescope still in Italy received the green looked, was designed in a joint effort led Critical Design Review (CDR) of the light to be shipped to Chile. The tele- by INAF–OAC, which made the analysis ­primary and secondary mirror systems, scope error budget was revisited and the jointly with BCV srl, and with full support

The Messenger 146 – December 2011 3 Telescopes and Instrumentation Capaccioli M., Schipani P., The VLT Survey Telescope Opens to the Sky

from ESO’s Technology Division, while actuators, simulating years of work of the force setting capability; they perform the mechanical design was committed to support systems with uninterrupted small differential force adjustments gen- Tomelleri srl. 24-hour testing performed for several erally with an error of just ±0.2 N, better weeks at an accelerated rate. than expected (budget: ±0.5 N). The concept of the secondary mirror ­support system was also significantly up­­ With a few months of hard work, in early dated by INAF–OAC in order to improve New accident, new recovery 2009 a team composed of people from reliability and performance. The mechan- Padua (Observatory and University), ics of the hexapod were slightly improved In early 2009 the support system was Capodimonte and INAF Headquarters, by ADS International srl, while the modi­ ready to be shipped. Unfortunately, together with the industrial support of fication of the control electronics was another major transport accident Tomelleri srl, completed the work on the shared between ADS for the leg electron- oc­curred. The vessel carrying the mirror remaining subsystems: adapter/rotator, ics and VSTceN for the Local Control cell, which had left Livorno at Easter, probe optics, Shack–Hartmann wavefront Unit. New control software was written at was delayed around Toulon by a general sensor, atmospheric dispersion corrector INAF–OAC, replacing the old version average. Two months passed before (ADC), were all tested and debugged for made obsolete by the new hardware. At the ship set out again for Chile, but once the electromechanical part. The technical the end of 2008 the secondary mirror sup- the load reached Paranal it became CCD systems were also put into opera- port system was effectively tested at sys- apparent that a fair amount of water had tion. These units were shipped to Chile in tem level and shipped to Chile, where in penetrated the moisture barrier bag mid-2009 and reassembled on site. early 2009 it was installed at the telescope ­protecting the M1 cell and had caused and verified on site. The secondary mirror severe damage. Meanwhile, other activities continued. could now perform relative displacements The telescope control software was along the optical axis with a precision The cell had to be re-imported back to improved and tested, using the VLT con- of about 0.1 μm (budget: 0.5 μm), and in Italy for re-manufacturing and qualifi­ trol model facility at ESO Headquarters; the XY-plane with precision of 1–2 μm cation of the whole system, and, in par- a cabling plan was prepared and then (budget: 5 μm) at any altitude angle. ticular, of the most critical component ­followed during the integration; some of the whole telescope, the primary mirror parts of the cooling system were revisited Both the primary and the secondary supports. This phase ended with suc- because the old design did not fulfill all ­mirror support systems were extensively cessful system tests in April 2010. The the real needs; the active optics operat- tested in Italy in all gravity conditions accident had ­further shifted the schedule ing model was studied in detail; the using tilting test devices, undergoing of the project back by one year. The wavefront sensing was simulated; much severe qualification of both performance recovery activity was supposed to be a optomechanical integrated analysis was and reliability. A good MTBF (mean “mere” repetition of the work already carried out; the software interface with time between failures) was assessed by done but, surprisingly, the replacement of OmegaCAM was tested; the transfer intensive tests on a subset of ten M1 some obsolescent commercial compo- function of the axes was measured both nents by nominally identical parts caused in Naples and again in Paranal, giving unexpected problems which were solved an altitude-locked rotor eigenfrequency Figure 4. The total complement of telescopes on the by changes in the control system. In of 9 Hz, in reasonable agreement with the Paranal platform: the UTs and the auxiliary tele- scopes are joined by the latest addition of VST on the end the primary mirror supports control simulations; and many much less the right side (north-east). turned out to have very good differential significant activities were also performed. Gerardo Ihle/ESO Gerardo J.L. Dauvergne & G. Hüdepohl/ESO

Figure 5. The 2.6-metre VST primary mirror in the coating plant.

4 The Messenger 146 – December 2011 Recent years in Chile relationships established with the other guide probe smaller than 0.1 arcseconds. teams nullified this risk: a human addition Good performance was also maintained The reintegration in Paranal was per- to a technical success in this case. The during windy nights, with wind speeds formed in three different steps, always in INAF team, composed of about ten up to 18 m/s, by closing the ventilation strict collaboration with ESO. The first ­people from Capodimonte, Padua and doors and using the wind screen. was the installation of the hydrostatic Arcetri, enjoyed the collaboration with bearing system for the azimuth rotation OmegaCAM and ESO, as well as with the and of the telescope mount, which ended Dalkia engineering people hired in Paranal Active optics in 2008. In 2009 the remaining parts of (the first light photo is shown as Figure 1 the telescope were shipped, but only the in Kuijken p. 8). The active optics was indeed an exciting secondary mirror support system was part of the job. That system had been put in place, due to the damage to the It must be added that the relatively small the major recent concern; we had to primary mirror cell. The missing work was mirror diameter does not simplify things prove the effectiveness of the new con- completed in 2010 when the mirror cell much with respect to a 8–10-metre tele- cepts that we had implemented for returned to Paranal (never had a mirror scope; in fact, it can make life even the primary and secondary mirror sup- cell travelled so much!), allowing the harder due to lack of space and reduced port systems. This was relatively straight- installation of the mirrors, adapter/rotator accessibility. Nevertheless, the commis- forward. After two nights of work we and ADC. The mirrors were coated and sioning of the VST was planned to take had successfully converted the Shack– installed in the telescope with the close only a few months, including the camera Hartmann aberration angles into M1 and collaboration of ESO, Tomelleri srl and commissioning. Everybody knew that M2 coordinates and the active optics ADS International srl. The missing parts this was an ambitious goal, but not unre- loop had been closed: we could already of the cooling system were also installed alistic, for two reasons. First, the massive reduce the amount of aberration we saw by EIE srl. amount of preparatory work: there was on the workstation panels. But still there little to invent from scratch on the moun- was a hidden problem, which we only By the end of 2010 the telescope was tain. Second, ESO support: the INAF discovered some weeks later: the Shack–­ integrated and pre-aligned. There were team could always count on the Paranal Hartmann sensor suffered from static some missing details, but also great people. In addition, one of the best aberrations in the non-common path, urgency: the commissioning team there- ESO telescope control experts and the which was dominant for some modes fore accepted that the missing aspects Garching guru of active optics joined with respect to the real aberrations of the would be taken care of in parallel with the team. The commissioning plan was telescope. In other words the measure- the night work, starting in January 2011. strictly followed and completed on time. ment was corrupted, but we were able to Then a fourth large integration step was Nevertheless, at the end of the sched- make a software fix. taken: the installation of the camera in uled activities, we realised that the image March 2011 by the OmegaCAM consor- quality of the telescope on the whole Another major improvement was also tium, with some involvement of the VST field of view could be improved by addi- necessary: by design the primary mirror commissioning team for the electro- tional shimming, discussed below, which support has no passive system that mechanical interfaces and the final bal- was done in July 2011. automatically compensates for the ancing of the telescope. The latter is now change of axial weight. This caused, as balanced with a remarkable 3.6-tonne expected, incorrect forces on the three counterweight on the top ring, which for- Pointing and tracking axial fixed points if no action was taken, tunately did not detract from the good especially at large zenith angles, gen­ tracking performance. Work on the axis control loops was erating trefoil aberration. The other M1 expected to proceed smoothly, because aberration modes proved to be much the loops had already been success- more stable. In order to be compliant Commissioning fully tuned in Italy in 2006 and we were with any operational scheme, we confident we could do it again. This was removed the root cause of the trefoil with Commissioning is the last fundamental the case: no real show-stoppers were a background software task that makes step, i.e. the transformation of a big encountered; also for the pointing model the system astatic. The active optics piece of iron and glass into a telescope. and autoguiding, which of course had ­system is now fully operational: the aber- At the time of writing, this stage has just never been tested before. The pointing ration coefficients measured by the been successfully completed. accuracy is at the level of 1 arcsecond Shack–Hartmann sensor can usually be root mean square (rms), with a best score reduced to an acceptable level in two The commissioning of the telescope and of 0.8 arcseconds so far. The tracking iterations. of its camera should take place together, axes have a blind tracking error against because OmegaCAM needs a working their own encoders of the order of a few VST to be tuned and vice versa. The 10 –2 arcseconds rms, lower than speci­ Alignment management of this interaction between fication. The VST guiding system with its the teams of OmegaCAM, ESO and VST guide probe is fully operational and The alignment was one the hardest parts could have become critical. But the good ­enables an image centroid error on the of commissioning, because the wide

The Messenger 146 – December 2011 5 Telescopes and Instrumentation Capaccioli M., Schipani P., The VLT Survey Telescope Opens to the Sky

FWHM vs. x–position FWHM vs. y–position Radius vs. Ellipticity 2.0 2.0 0.6 c) c) se se 0.5 rc rc 1.5 1.5 (a (a

ty 0.4 ci GE GE ti MA MA 1.0 1.0 llip 0.3 E _I _I

0.2 WHM WHM F F 0.5 0.5 0.1

0.0 – 5 000 0 5000 – 5 000 0 5000 062000 4000 000 8000 10 000 Xpos–CRPIX1 (pixel) Ypos–CRPIX2 (pixel) Distance from optical axis (pixel)

Figure 6. Image full width at half maximum vs. X off- As a consequence of all this testing For the ESO Paranal and Garching team: Ueli set (left) and Y offset (centre) are shown to be homo- and the concomitant reliability, the tele- Weilenmann, Andreas Kaufer, Octavio Lavin, Ricardo geneous after the alignment of rotator and optical Parra, Matteo Pozzobon, Mario Tapia, Thomas axes. The image ellipticities, shown at right as a scope is already delivering seeing-limited ­Szeifert, Juan Osorio, Ismo Kastinen, Guilermo function of radial offset, are mostly within 10%. images, with seeing measured by the Valdes, Ivan Munoz, Stephane Guisard, Lothar Astronomical Site Monitor down to Noethe, Franz Koch, Michael Mueller, Michael field imposes much tighter requirements 0.4 arcseconds. Thus, it is now ready to Esselborn, Henri Bonnet, Jaime Alonso, Gerd ­Hüdepohl, Toomas Erm, Dietrich Baade, Olaf Iwert, than for a normal telescope. We could survey the sky, and we are ready to work Cristian Romero, Duncan Castex, Cristophe Geimer, remove a large amount of off-axis astig- on the images using both AstroWise, Miguel Riquelme, Steffen Mieske, Fernando matism by aligning M2 with M1: once the software package developed by the Selman, Stefan Sandrock, Frederic Gonte, Guillame we knew the correct measure, the cor- OmegaCAM consortium, and VST-Tube, Blanchard, Gerardo Ihle, Arno Van Kesteren, Nicolas Haddad, Andrew Wright, Alex Segovia, Pierre rection was easily implemented using the another package designed at OAC to ­Sansgasset; hexapod. But the telescope still suffered process VST images specifically. This lat- for the Dalkia team: Yerco Juica, Luis Romero, from a focus gradient. Indeed, after the ter package is an automated pipeline ­Cristian Garrido, Edu Fernandez; installation of the camera, a misalignment going from the raw exposures to fully cal- for the Tomelleri Srl team: Raffaele Tomelleri, Pierfrancesco Rossettini, Francesco Perina, Stefano between the rotator and the optical axis ibrated co-added images, and extrac- Recchia, Alessandro Da Ronco; was clearly detected. This had negligible tion of catalogues with aperture and point for the ADS International srl team: Daniele Gallieni, effects on about 70% of the image, but spread function photometry. A set of Pierluigi Fumi, Enzo Anaclerio, Paolo Lazzarini; caused a degradation on one side of the tools allows us to administrate the data for the EIE team: Gianpietro Marchiori, Andrea Busatta, Cristina Battistel. mosaic, which was out of focus. This and check the quality of the intermediate problem could only be solved by shim- and final products. VST-Tube comes Key people who, in various fields, helped to rescue ming the rotator flange, with a lot of with a Graphical User Interface to facili- of the telescope project at various stages, from CDR mechanical work and some suspense tate the inter­action between data and to the integration in Chile, are: Massimo Brescia, Davide Fierro, Giacinto De Paris, Francesco Perrotta over the angle of the shims, which was user. The capabilities of this software and Paolo Vettolani. fortunately correct! Now the image quality have been recently proven as it was is homogeneous over the whole mosaic applied to produce the monochromatic Special thanks are due to Jason Spyromilio and as expected by design (see Figure 6). images combined by ESO for the picture ­Roberto Tamai for their constant constructive ­criticism. of the globular cluster Omega Centaurus (front cover image). In passing we note Last but not least, Konrad Kuijken and the whole Prospects that a preliminary reduction of these OmegaCAM team were great partners in the images leads to limiting stellar magni- telescope+camera commissioning. During commissioning the telescope has tudes that are perfectly consistent with The Italian Ministry of University and Research reached a good level of performance, the expectations. (MIUR), the Italian National Institute for Astrophysics as discussed above. Last but not least, (INAF) and the Regione Campania, are acknowl- the system has regularly worked for the edged for their financial support. whole duration of these activities with Acknowledgements a technical downtime less than we could References The proposal, study, design, and realisation of the optimistically have expected for such VST telescope was the result of the joint effort of a Capaccioli, M., Mancini, D. & Sedmak, G. 2003, a phase. The VST commissioning pro- number of people who are acknowledged here as a Mem. SAIt, 74, 450 whole. The following list is just for the last few years. cess has finally concluded with the Pre- Capaccioli, M., Mancini, D. & Sedmak, G. 2005, Even so, it is quite long and we run the risk of forget- liminary Acceptance Chile (PAC) being The Messenger, 120, 10 ting someone (for which we apologise in advance). granted by ESO.

6 The Messenger 146 – December 2011 Telescopes and Instrumentation

Appendix: Overview of INAF–GTO Surveys

Nicola R. Napolitano1 STEP: The SMC in Time: Evolution of a Pro- evolution of galaxies (down to M* = +6) as a totype interacting late-type dwarf galaxy function of their mass and environment, PI: Vincenzo Ripepi (INAF–Capodimonte by covering a field of 23 square degrees cen- 1 INAF–Capodimonte Astronomical Observa- Observatory) tred on the core of the Shapley supercluster tory, Naples, Italy The intent is to derive the color–magnitude (z = 0.048). It will be possible to track the evo- diagrams of the oldest population of the Small lution of galaxies from field to filaments and Magellanic Cloud (SMC) down to 1–2 magni- groups up to the cluster cores and to investi- The VST/OmegaCAM facility provides multi- tudes below the main sequence turn-off. This gate what is the primary location for galax- band images of unprecedented quality, suita- will help to break the age–metallicity degener- ies to be transformed. The survey­ will extend ble for the investigation of a range of cutting- acy and recover the star formation history the multi-wavelength (far-ultraviolet to far-­ edge issues, such as the constituents of the of the galaxy and of the Magellanic Bridge. infrared) ACCESS survey ongoing in the super- Milky Way and its companion galaxies, the Classical variable stars (RR Lyrae, Cepheids, cluster core. structure of nearby galaxies, galaxy for­mation anomalous Cepheids, δ-Scuti stars, etc.) will processes in different environments from the be used as population tracers, especially in VOICE: VST optical imaging of the CDFS and field through clusters to superclusters, the the unexplored region of the Bridge. The sur- ES1 areas search of intermediate redshift supernovae, vey, which is synergic with the VISTA Public PI: Giovanni Covone & Mattia Vaccari (Univer- the search/study of Active Galactic Nuclei Survey VMC, will also shed light on the first sities of Naples & Padua) (AGNs) and quasars, and finally the study of stages of star formation by securing a com- VOICE is a multiband (u’, g’, r’, i’ to AB ~ 26) dark matter distribution in the Universe by plete mapping of pre-main-sequence objects. optical survey of the central regions of the weak lensing. Of course, based on previous Chandra Deep Field-South (CDFS) and ES1 experience with survey telescopes, a major STREGA@VST: Structure and evolution of fields (8 square degrees in total). These areas outcome can also be expected from serendip- the galaxy are of paramount interest for the community itous discoveries. PI: Marcella Marconi (INAF–Capodimonte as they have been, and will be, targeted by Observatory) deep ultraviolet (GALEX–DIS), near-infrared The science division of VSTceN (for several This survey addresses the issues of the for­ (VISTA–VIDEO), mid-infrared (Spitzer–SERVS years led by Juan Alcalà Estrada) has coop­ mation mechanisms in the Galactic halo by: and Spitzer–SWIRE), far-infrared (Herschel– erated with the PIs of the INAF–GTO survey i) tracing tidal tails and haloes around stellar HerMES), and radio (ATCA–ATLAS) surveys. programmes with the aim of monitoring their clusters and galaxies; ii) mapping extended The uniform and deep optical coverage still degree of competitiveness. Following revision regions of the southern portion of the orbit of missing on these fields will be suitable for gal- in 2008 some of the surveys were dropped. the Fornax dwarf galaxy; iii) possibly identify- axy formation studies out to z ~ 1 and for In 2009, just before the accident to the VST ing new very faint stellar systems using recent gravitational lensing. cell, INAF and VSTceN organised a workshop techniques developed by the Sloan Digital in Naples to discuss the current programmes Sky Survey (SDSS). Stellar tools will be used VEGAS: VST survey of Elliptical Galaxies in and gather new ideas for VST–GTO exploita- to achieve the science objectives: variable the South hemisphere tion. This led to a call for letters of intent. A stars (RR Lyrae and long-period variables), PI: Massimo Capaccioli (University of Naples comprehensive summary of the projects was turn-off and main sequence stars. Federico II) presented at the ESO VST Public Surveys This deep multiband VST survey of nearby and GTO Programmes Review meeting in Extension in the u’-band of the WINGS Sur- elliptical galaxies in the southern hemisphere 2010 resulting in a synthesis which took into vey (Wide field Imaging of Nearby Galaxy is expected to reach 27.5, 27.0, 26.2 mag account the synergies among GTO projects clusters Survey) ­arcsecond−2 in g’, r’, i’, respectively. The aim and ESO Public Surveys. Brief summaries of PI: Mauro D’Onofrio (University of Padua) is to: i) trace the light distribution out to ten the INAF–GTO programmes follow. The survey aims at obtaining deep ­u’-band effective radii (Re); ii) derive colour gradients images for ~ 50 galaxy clusters in the redshift and measure the surface brightness fluctua- SUDARE: Supernova diversity and rate range 0.04 < z < 0.07, which already have tion gradients out to a few Re, for stellar popu- ­evolution complete B, V, J, K and spectroscopic infor- lation characterisation; and iii) obtain a full PI: Enrico Cappellaro (INAF–Padua Observa- mation from the WINGS survey. The u’-band census of the satellite systems (globular clus- tory) imaging of the WINGS clusters gives a first ters and dwarf galaxies) out to 20% of the gal- The aim of the survey is to measure the rate of chance to study in detail the star formation axy virial radii. the different types of supernovae (SNe) at activity in a statistically significant sample ­redshift z ~ 0.3–0.6 and, by comparison with of cluster galaxies and to establish the corre- A VST-OmegaCAM survey of Local Group local rates, probe the evolution of SN diver- lations between such activity and the gal- dwarf galaxies sity with cosmic time. Statistics of SNe in dif- axy morphology (from V-band imaging) and PI: Enrico Held (INAF–Padua Observatory) ferent environments and as a function of red- masses (from K-band data), and the link with The survey aims at carrying out a multiband shift are a key test of the coherence of stellar the environment. (B, V, i’, u’) wide-field survey of southern evolution theory, SN explosion mechanisms Local Group dwarfs, extending well beyond and the relation between nucleosynthesis and VST-ACCESS (A Complete CEnsus of Star the current nominal tidal radii. The survey galaxy evolutionary scenarios, through some formation and nuclear activity in the Shapley will represent the most complete mapping of of their basic ingredients, namely star forma- supercluster) dwarf galaxies and provide useful targets for tion history, chemical enrichment, and feed- PI: Paola Merluzzi (INAF–Capodimonte Obser- follow-up spectroscopy as well as an insight back effects. The project is also intended to vatory) into the variations of the stellar populations. build up experience and test tools that will be This is a multiband (u’, g’, r’, i’, z’) survey pro- The proposal is based on both OmegaCAM needed for future all-sky synoptic surveys. ject aimed at determining the importance and INAF–GTO. of cluster assembly processes in driving the

The Messenger 146 – December 2011 7