Telescopes and Instrumentation ESO VISTA Public Surveys — A Status Overview 1 500 Figure 1. Overview of Magda Arnaboldi P85+ Marina Rejkuba1 the VISTA time alloca- 1 400 tion in hours. P85+ Jörg Retzlaff P86 included dry runs which 1 Nausicaa Delmotte 300 were executed before Reinhard Hanuschik1 P87 the official start of VISTA Michael Hilker 1 200 operations. 1 P88 Wolfgang Hümmel 100 Gaitee Hussain1 Valentin Ivanov 1 0 P89 e V S C Alberto Micol1 O VV VH 1 VM VIDE Mark Neeser VIKING 1 Monika Petr-Gotzens Open tim Ultra-VISTA Thomas Szeifert 1 Fernando Comeron 1 six VISTA PSs from the extended period imager VIRCAM is provided by Emerson Francesca Primas 1 85 to period 89 (P85–P89). et al. (2006). Observation preparation Martino Romaniello 1 and submission for public surveys is The implementation of the PSP recom- done on a half-yearly basis, following the mendation on time to survey completion standard ESO service mode procedures. 1 ESO implied a revision of the standard VLT The PIs of VISTA public surveys and their model of scheduling observing time in teams submit Observation Blocks (OBs) service mode because the VISTA public — the standard basic observing units. The ESO policies for public surveys survey programmes are all essentially The deeper surveys (Ultra-VISTA, VIDEO, include regular monitoring and reviews at the highest priority of execution. As an VIKING and VMC) have typically ~ 1-hour- of the progress of the surveys to en- added complexity, normal programmes long OBs, while the wide surveys (VHS sure their legacy value and scientific were scheduled alongside public surveys and VVV) have OBs lasting between 5 competitiveness. The review process is and Chilean programmes from P87. and 30 minutes. The survey with the larg- carried out on the basis of reports by Because the former have top priority and est number of submitted OBs is VVV: the ESO survey team and the survey PIs essentially cover all observing condi- because of the multi-epoch observations submitted to the relevant Public Survey tions, normal (open time) programmes the total number of OBs prepared and Panel (PSP) — the VISTA PSP in this must also be assigned a similar priority if executed will be of order 30 000. Figure 2 case. A summary of the time allocation they are to be executed at the telescope. shows the number of hours of execution to VISTA surveys, the service mode Starting from P88, normal programme of OBs each month for all VISTA surveys. observations and the current progress observations are not carried over regard- The time charged for each OB execution after two years of telescope operation less of their ranking, to avoid extra car ry- is only counted for successfully com- is provided. Furthermore the content overs hindering the progress of the pleted observations and Figure 2 shows of the data products delivery by the surveys. To limit the impact of open pro- the completed OB hours that are com- survey teams to the ESO Science grammes on the progress of the VISTA puted by the observation preparation Archive Facility is described. PS the following policy has been imple- software (P2PP3). While in the first year mented since P89: open time proposals of the operations there was still some can access restricted right ascension fine-tuning of the operational procedures Phase 1 — time allocation to surveys ranges, but should carefully justify the and overheads, now the overheads com- scientific goals and why these scientific puted by version 3 of the Phase 2 Pro- Scheduling of the VISTA Public Surveys goals are not achievable through the posal Preparation system (P2PP3) are (PS) is done in line with the VISTA PSP scheduled PS. very similar to the actual time needed to recommendation that every effort should execute the observations. be made to complete the surveys within five years. Realistic expectations on what Phase 2 — service mode observations The histogram in Figure 2 shows the can be executed in the next semester for public surveys effect of technical interventions on are also taken into account, based on the speed of execution of the public sur- ex perience gained from the previous VISTA public surveys are ambitious vey OBs, with the main impact falling semester(s) of VISTA operation. The time programmes which entail very large allo- in the period 3 April 2011 to 4 May 2011, allocation to surveys is based on the cations of time, of order of 1800 to which coincided with the recoating of updated observing request by the PS 3400 hours, with consistent observing the primary (M1) and secondary (M2) mir- principal investigators (PIs) and takes into conditions. For a summary of the scien- rors with aluminium due to fast degra- account the carryover time needed to tific goals of the VISTA public surveys, dation of the original silver coating, and complete the observations submitted in their area coverage and photometric an extended recovery and maintenance the previous period. Figure 1 provides characteristics, see Arnaboldi et al. (2007). of M1. an overview of the time allocation to the An overview of VISTA and of its wide-field The Messenger 149 – September 2012 7 Telescopes and Instrumentation Arnaboldi M. et al., ESO VISTA Public Surveys — A Status Overview 250.0 Figure 2. Histogram of VISTA public survey completion rates the number of hours of execution of OBs each month for all VISTA sur- Here we present the current fraction of 200.0 veys up to 1 April 2012. completeness for each VISTA PS and the r) Quality control grade A expected time to completion, based on (h is assigned to OBs com- the current efficiency of execution. The n 150.0 pleted fully within io requested constraints absolute completion rate is based on the- (i.e. sky transparency, oretical OB execution times as computed ecut 100.0 image quality, airmass, by the P2PP execution time module and ex Moon illumination, etc.), the time requested by the PI of each sur- OB while grade B is assigned to those OBs vey for the total duration of the project, 50.0 for which one of the as described in the Survey Management constraints is violated Plan (SMP). The absolute completeness up to ~ 10%. fraction is given by the ratio of the com- 0.0 pleted OB time divided by the time re­­ 11 11 11 11 11 11 12 12 10 10 10 10 10 10 09 r- r- v- y- r- quested in the SMPs. The completion y- v- v- Jul- Grade A Jul- Jan- Ma No Sep- Jan- Jan- Ma Ma Ma rates are calculated for the observations No Sep- Ma No Grade B up to the end of Period 88 (end of March In order to enable the survey teams to area definition file generated with SADT. 2012), hence they cover the first four prepare large numbers of similar OBs In this way hundreds of similar OBs periods of VISTA operations. In these four and for ESO user support and science that adopt the same observing strategy periods, the effective telescope time operations to verify and execute them and point to different areas in the sky is about 1.75 years, as there were three in the most efficient manner, new tools are generated automatically, thus pre- months of technical downtime (mirror have been developed (Arnaboldi et al., venting typing errors and saving time. In coating, M1 intervention and technical 2008). We list them briefly: addition to an interface with the SADT, downtime to correct the focal plane tilt). this tool also allows the survey PIs to These technical interventions affected The Survey Area Definition Tool (SADT) define the survey observing strategy via mostly the VVV and Ultra-VISTA projects, was developed by the VISTA consortium scheduling containers. These concepts as they took place in those months (led by J. Emerson) and delivered as can be easily encoded in an automatic when either the Milky Way Bulge or the part of the United Kingdom in-kind con- ranking algorithm that suggests to the COSMOS fields are visible. tribution to joining ESO. The main role observers which OB is to be selected out of the SADT is to efficiently mosaic the of many thousands of similar survey OBs. The absolute completion rates of the survey area and to identify the necessary The OT is used on Paranal for selecting surveys at the end of P88 are listed in active optics and guide stars for each the observations to be executed; it has Table 1. These can be used to extrapo- tile. The SADT has been further improved the VISTA-specific ranking algorithm late the time necessary to complete following the experience gained during (Bierwirth et al., 2010) as well as report- the VISTA public surveys, assuming that VISTA science verification, dry runs, and ing functionality. the observations continue at a similar the first period of observations (P85+). pace. From these assumptions, the VHS The latest improvement was to introduce Survey Monitoring and Visualisation survey can be completed in about five the 2MASS catalogue transformation Tool (SVMT) is a new tool developed to years, while VVV, Ultra-VISTA, VIDEO and to I-band magnitudes, which is now used facilitate the Phase 2 review of thousands VMC are all expected to take more than for guiding and active optics on VISTA. of survey OBs and to enable monitoring seven years. These numbers are lower This is important, as it was noticed that of the survey observations. The main limits as the requested observing time in other catalogues suffered from low reso- functionalities are the display of the sur- the SMPs was computed using overhead lution, containing binary stars or galax- vey areas and the OB status for selected values that later proved to be underesti- ies, and some defects (e.g., containing areas or survey runs, and the visualisa- mates.