Vista Hemisphere Survey Newsletter: Issue 1 (September 2006) ------------------------------------------------------------- see also http://www.ast.cam.ac.uk/~rgm/vista/vhs/news/ Introduction: ------------ This is quite long since I decided to collect up alot of information. A new draft of the VHS proposal will be circulated tomorrow. See Section 5 below for my current thoughts are how the proposal should be descoped in response to the PSP report. Contents -------- 1. Mailing lists and Web Pages 2. ESO Public Survey Panel(PSP) Feedback (received May, 2006) 3. VHS and The Vista Dark Energy Proposal 4. Report from ESO PSP meeting (Held in Edinburgh June 21/21rd, 2006) 5. Resubmission to ESO (Due Friday, 29th Sep, 2006) [ACTION NEEDED: PLEASE COMMENT ON THE THIS ASAP] 6. Other News; LSST update 1. Mailing lists and Web Pages ------------------------------ o Please subscribe to the mailing list described below or email me directly(rgm@ast.cam.ac.uk) to ask me to subscribe you. o Please visit https://lists.cam.ac.uk/mailman/listinfo/ast-vhs-announce There is a VHS web page here: www.ast.cam.ac.uk/~rgm/vhs/ This contains various supporting documents and links including the submitted VHS proposal and copies of the VDES and VIKING proposals. There is also a link to the VST ATLAS proposal which is relevant to VHS. There is a Wiki system hosted here: http://wiki.astrogrid.org/bin/view/VISTA/VHS This has the advantage that anyone can upload documents to it. Two mailing lists with archives have been set up. Users can either receive the emails or just browse the contents of lists at your leisure. o ast-vhs -- VISTA Hemisphere Survey https://lists.cam.ac.uk/mailman/listinfo/ast-vhs This is intended for discussion and at the moment you each have to register yourself. The contents of the email archive for this list is private i.e. you need a password. If you want to be subscribed either email me or try the registration page here: https://lists.cam.ac.uk/mailman/listinfo/ast-vhs o ast-vhs-announce -- VISTA Hemisphere Survey announcements. https://lists.cam.ac.uk/mailman/listinfo/ast-vhs-announce This is intended as a low traffic moderated list. Access to the contents is public i.e. no password. I have registered all co-Is on this. There is information about the PSP already in the archive To post a message to all the list members, send email to: ast-vhs-announce@lists.cam.ac.uk. 2. PSP Feedback --------------- Verbatim from the PSP(received in May) McMahon: The VISTA Hemisphere Survey (VHS) The proposal aims to image the entire Southern celestial hemisphere in four bands. The panel agreed that the proposal has a large legacy value. However the total time required is very large and the PSP believes that covering the sky in J+K is a considerably higher priority than Z+Y. At the beginning of the proposal, it is mentioned that 7500 deg2 could be surveyed in Z+Y initially, but the proposal does not explicitly discuss which 7500 deg2 of the sky are considered. The proposers do not discuss the science goals behind the annual scan of the SDSS SGC equatorial strip. How much time is being devoted to this? Is it important to do this in all filters? The proposers discuss prioritising the targets but it is not clear why that particular strategy was selected, nor what scientific gains would accrue. Since this approach would certainly have an impact on the efficiency of the survey, the proposers should discuss the detailed observing plan and the perceived advantages and costs . The Panel strongly recommends that the PI submits a new proposal which focused on the science that can be achieved by covering the whole southern sky in J+K only. If the PI wishes he could add, as an option to be implemented at a later date, the additional observations in the Z+Y filters. Of course the incremental scientific objectives that could be achieved with these observations should also be part of the optional proposal. The panel felt that this strategy could provide a legacy database at the earliest opportunity. The panel asks the PI to contact Castander to discuss the Z+Y imaging in the area of the sky proposed by Castander (to be observed by DES) and to determine how this would add to the scientific objectives of the survey. 3. VHS and the Vista Dark Energy Proposal ----------------------------------------- The final sentence from the PSP report to Castander said: "The Panel recommends that this proposal should not longer be considered. Most of the scientific objectives could be achieved within a revised proposal by McMahon. The PI is encouraged to contact McMahon." A copy of the submitted VDES proposal is here: http://www.ast.cam.ac.uk/~rgm/vista/vhs/ Following the advice of the PSP I contacted Francisco Castander and we met in Cambridge in early June. As background, VDES requested 250nights to survey 5000deg^2 to J~21 and K~19 with exposure times of 300secs in J and 324secs in K. The region of sky is defined by the Dark Energy Survey. This is led by Fermi Lab in the US with US, Spanish and UK partners. The Dark Energy Survey(DES) will use a new wide field CCD mosaic camera called DECam that is currently under construction. The DES camera focal plane will consist of sixty-two 2k x 4k CCDs (0.27''/pixel) arranged in a hexagon covering an imaging area of 3 sq. degrees. The survey will use 525 nights on the CTIO 4m, over 5 years starting in Fall 2009. The DES design reference survey strategy is to survey the full 5000deg^2 in year 1 for 200secs per band reaching 10sigma limits[AB mags] in g, r, i and z of 24.1, 23.7, 23.3 and 22.6 respectively. The same strategy is planned in year 2. The goal for the full 5 years is a total exposure of 400, 400, 1200, 2000 secs in g, r i and z respectively with 10sigma limit of 24.6, 24.1, 24.3 and 23.9. See https://www.darkenergysurvey.org/ for more details. DES data may be made public on a timescale of 6-12months after observation. This is still under discussion. Castander and McMahon agreed that a goal for VHS could be to: (i) cover full DES region (excluding the region of DES covered by VIKING i.e. around 500deg^2) with VHS by end of 2009 i.e. First 3 VISTA seasons. Thus by the end of the first season of DES we would have 5000deg^ in griz(DES) + JK(VHS). Note that some of the DES region would also be covered by VST ATLAS so that independent of DES, VHS would be getting optical data over part of this region. (ii) propose to PSP that to double the VHS Baseline exposures in J and K from 60secs to 120secs in the DES region. McMahon agreed to propose this to the PSP. 4. Report from ESO PSP meeting (Held in Edinburgh June 21/21rd, 2006) --------------------------------------------------------------------- From the Agenda for the PSP meeting: The main purpose of the meeting is to carry out the second phase of the plan outlined in the ESO procedures for Public Surveys and specifically its point number 3 (below). 3. ESO will establish a Public Survey Panel (PSP) including scientists expert in a broad range of current astronomical research, with particular emphasis on those areas that can profit from Public Surveys. The PSP prime mandate will be to review the Public Survey Proposals and elaborate a scientifically and observationally well coordinated set of Public Surveys. This process may well imply merging different proposals, or expanding their aims beyond the original ones e.g., in the filter set, depth, area, coordinates, etc. In order to achieve these goals the PSP will involve representatives from the selected teams having submitted Survey Proposals. On the basis of the achieved coordination the selected survey teams will modify the survey proposals, describing the scientific rationale, observational strategy, and data product specifications (e.g. photometric and astrometric accuracy, images, catalogs, delivery time, etc.) as agreed in the course of these activities. Membership of PSP ----------------- Duccio Macchetto(STSCI+ESA) (Chair) Ivan Baldry(UK) Felipe Barrientos(Chile) Russell Cannon(Australia) Mark Casali(ESO) Alberto Franceschini(Italy) Danny Lennon(UK) Marc Moniez(France) Jo Silk(UK) Also present: ------------ Jorge Melnick(ESO VLT Scientist) Jim Emerson(VISTA PI) Magda Arnaboldi (Head of ESO Surveys Team) Survey PIs Present ----------------- Jarvis (VIDEO) Cioni (Magellanic Clouds) Minniti (Galactic Bulge) McMahon (Vista Hemisphere Survey) Fynbo (Narrow Band Survey) Dunlop (UltaDeep Survey-1) Franx (UltraDeep Survey-2) Le Fevre (UltraDeep Survey-3) Sutherland (VIKING) Lucas (Galactic Plane) ------------------------------------------------------------------- The ESO PSP meeting in Edinburgh was interesting. It covered material that is already on the ESO web site. In particular the ESO Policies for ESO Public Surveys at http://www.eso.org/observing/AboutSurveys.html The main advantage from the meeting was that one found out what the most important sentences and phrases are in the Policies were. Having said this I found this somewhat unsatisfactory since there was no real dialogue between the PIs and the PSP. Informally I discussed some of the feedbacks with members but there was no formal PSP response more than to read the policies and resubmit. It was also an opportunity for PIs to meet. One major outcome was that the location of an Ultra-deep VISTA survey was determined and the three Ultra-Deep proposals will be merged into a single proposal. The Narrow band survey was also combined with this. This has a major effect on scheduling. The main contenders were the COSMOS(10hr+00d), CDFS(03hr-37d), UKIRT-UDS(02hr-05d) fields and the COSMOS fields was chosen. There are 6 proposals remaining after the merging of the 3 ultra-deep and the narrow band proposals. These were EACH asking for around 2000 hours. i.e. a full year of VISTA survey data. This merging was one of the main purposes of the meeting. There was some useful discussion about the RA distribution of the oversubscription. The main spikes were caused by the UltraDeep surveys and the Magallenic Clouds. The 6 proposals that are remain are: (1) MagClouds (2) Galactic Bulge(with Galactic Plane Survey as minor partner) (3) VIDEO (4) VIKING (5) VHS(with input from VDES) (6) UltraDeep A summary of the basic parameters of these is below based on information provided at the PSP meeting. Some of the details are probable incorrect but the general flavour should be correct. (1) Mag Clouds (PI: Cioni) o SMC: 1.0hr, -72.5; (90deg^2) o LMC 5.5hr, -60.5; (255deg^2) o around 200deg^2 in to YJK to K(AB;5sigma)=23.0 (2) Galactic Bulge(PI: Minniti) (subsuming the Galactic plane survey) (3) VIDEO (PI: Jarvis) o ZYJHK survey to K(AB;5sigma=23.0 over 10deg^2 down from 30deg^2 o After the PSB feedback the VIDEO proposal is going to concentrate mostly on SWIRE fields, at 00.5, 02, 03.5 hrs (priorities TBC) (4) VIKING (PI: Sutherland) o 1500deg^2 in ZYJHK to K(AB;5sigma)=21.3 (5) VHS (PI: McMahon) [20,000 JK, K(AB:5sigma)=20.0, +ZY over reduced area] (6) A single ultra-deep field (merger of Dunlop, Franx, Dunlop and Fynbo) [outcome was a single ZYJHK Pawprint on the COSMOS(10hr+00) file to K(AB; 5sigma)=25.5] Other keys factors that were emphasised by the PSP panel were: 1. There is around 2000hrs per year available for Public Surveys 2. ESO will only permit two surveys to be active at the same RA hour bin during any observing period. 3. Two surveys can be active only if the observing conditions(eg seeing) that they require are different. 4. Accepted proposals will not be ranked. Conditions 2. and 3. are sufficient to define the observing priority according to ESO. 5. Proposals will be reviewed scientifically after two years. Some of this from the Policies for ESO Public Surveys http://www.eso.org/observing/AboutSurveys.html In my opinion, 2 and 3 are the main reason probably VDES was rejected outright since the VIKING survey was ranked higher than VDES. ESO and the PSP probably want to support a small number of surveys that are carried out quickly rather than supporting a large number of proposals that take longer to finish. VIKING plans to use image quality <1.0arc sec so VHS will need to accept 1.0 to 1.4arc sec seeing. VHS also has fields that are further from the ecliptic and hence moon and can more easily be observed in all wind direction. Thus VHS if accepted at the next stage VHS could get a significant amount of data in seeing <1.0 arc seconds. When questioned about how time would be apportioned between the various surveys DM responded that this would depend on the science case submitted at the next round. My view on that we need to realise that from ESO's point of view KIDS/VIKING is the front runner on LSS and DE science. It is starting at least 2 years before DES, covers 1500 degrees and will have observations over 9 bands ugrizYJHK I reported to the PAP that Francisco Castander(VDES PI) and I had met as advised in the PSP feedback and that we were considering requesting 120-150sec exposures in J and K over the DES region. The PSP did make any detailed response. In my opinion it would probably a scientifically better strategy to propose YJHK at 60secs each rather than JK with 120secs over the VHS/VDES/ATLAS common area of around 3000deg^2 as a high priority. Here is the menu of possible ways forward for VHS with VDES input: (A) Baseline 60secs in J and K over the DES region as a higher priority within VHS with the goal to complete the DES area by the time that DES completes its first pass in griz. i.e. end of 2009 or 2010. (B) Add 60sec in Z, Y and H to Baseline JK over the DES region (C) Double the VHS Baseline exposures from 60secs to 120secs in J and K to the DES region. 5. Resubmission to ESO (Due Friday, 29th Sep, 2006) --------------------------------------------------- This involves submitting a technical version of the proposal in the standard ESO OPC form and a resubmission of the VHS proposal taking into acount the PSP feedback. (i) VHS total request over 6 or 7 years. I propose to de-scope the ZY part of the proposal as advised by the PSP report. However, if we follow verbatim the PSP report some of the science goals cannot be met since they require ZY as well as JK. However, they may have had the view that VIKING would address this science in the short term. |-----------------------------------------------------------------------| | The original proposal was a 7 year program with over 20,000deg^2 with | | exposure times of 180, 180, 60, 60 in ZYJ and K.This required a total | | time of 7359hrs. With the new VISTA ETC(v1.3) this reduces to a | | total of 6750hrs. | |-----------------------------------------------------------------------| I propose to: (i) eliminate the |b|<5 part since this is covered in principle by the Minniti proposal. This reduces the area of |b|<30 sky from 10,000deg^2 to 8200deg^2 (ii) eliminate the 1500deg^2 region covered by VIKING from the |b>30 sky footprint; this leaves 8500deg^2 To cover 16700deg^2 in J and K alone for 60secs would require 1593hrs To meet more of the VHS science goals and including VDES. I propose that we aim to cover the non-VIKING 8500deg^2 in ZYJHK. PhotoZ results show that there is little difference between 120secs in J and K and the 60secs in YJHK. This is a good compromise between the VDES request and VHS goals. This is also adding H to VHS which is something the cool star science would benefit from. This will require a further 405hrs/band for 8500deg^2 giving an additional 1215hrs for YZH component or 810hrs for YH if we assume that Z comes from the VST or VDES. |--------------------------------------------------------------------| | The total request is then 2403hrs(1593+810) or 2808hrs(1593+1215). | | This could be a 6 year program at around 500hrs per year. | |--------------------------------------------------------------------| If we leave some scope for VIKING to be expanded at at later date from 1500deg^2 to 3000deg^2, we could reduce our High galactic latitude proposal to just 6000deg^2. This could be a future VHS descope option and saves 72hrs/band or upto 360hrs. (ii) First three years plan: Here we would target the 4500deg^2 in ZYJHK the that is planned to be covered by VST ATLAS. This overlaps around 3000deg^2 with the DES footprint (DES also overlaps around 500deg^2 with VIKING). VHS-HighB(4500deg^2) would require 215hrs per band; 1075hrs for ZYJHK or 860hr if Z is left to ATLAS. VHS-LowB would request 782hrs to cover upto 8200deg^2 of |5|