UKIDSS meeting at Imperial 25/11/02 ----------------------------------- Nigel Hambly Archive: will be based on archive already at ROE. ------------ Some form of archive is needed at first light, but not needed to be fully functional until +1 year (V2), then V3 Grid enabled (Virtual Observatory). SJW - perhaps need V2 a lot earlier. V1: images - 4 macrosteps (resampling tools needed at V1) proximity matching finder charts based on SDSS Data Release 1 (March/April). EDR used Objectivity, but having difficulty. DR1 will use a MS based data base manager. will be tested using SSS will provide additional simple interface for quick queries power users will use SQL V2: more plotting access across super frames stacked frames (user-specified) new source extraction options (?) (SJW - some users (PATT) will want stacking straight away) (MJI - stacking can be done within same observing block (MSB), but not from different nights) V3: In future Archive usage: went through science requirements and came up with ~20 usages. Discussed 5 survey requirements and ideas. Mike Irwin Pipeline: There are going to be 3 pipelines (1) data quality ---------- control (summit) (2) first pass (also summit) (3) UK side pipeline (Cambridge). Data transfer: IDE discs or tape. Discs may not be as reliable as first thought. C/b pipeline: process one night of data independently (bad pixel data, flat fields possibly from previous nights) Edinburgh: advanced pipeline - some rereduction (using data from different nights). C/b: further processing (in addition to APM stuff) eg. profile fitting, de Vac profiles etc. various flux measures. quick photometric calibration - using 2MASS - only good to 10-20%, so might not be good enough. need lots of standard stars to be measured Problems: need nightly extinction measurements constraints on interleaving standard set of parameters undersampling and interleaving - if interleave, do you get a smooth PSF? image retention from preceding frames Jim Lewis Described pipeline in a bit more detail. --------- Concerns: FITS headers - header driven pipeline - now under control flat fielding - varying over the night? Twilight, Sky, Dome - all have problems. STH doing tests. ROE also looking into dome flats (useful for pixel-to-pixel, something else used for vignetting). Bad pixels, bad reset corrections (WFCAM looks like it is stable) Dark correction - linear with time? varying over the night? Image retention & cross-talk - could spoil independence of each MSB, but it looks like image retention is small. Basic pipeline is complete. The advanced one is under development. Re-reductions (complete ones) will be done in C/b. Confidence map (MJI): noise varies around frame. A confidence map describes this. Detection will depend on this. Sextractor/APM differ mainly in the parameters that are output. Steve Warren Additional parameters etc.: GCS and GPS want profile fitting ------------ (dense regions), but this might be difficult since the PSF might vary. Said that PSF fitting of stars is a requirement. (Mike: 20% improvement in astrometry at faint end. Photometry perhaps 10-15% better additionally - but depends on knowing PSF). Main gain for PSF fitting is in crowded fields - GPS. Mike said that it can be done, but doesn't see why there is a need to apply it to all frames (not an easy problem). Perhaps process problem areas later. Nebulosity - varies on all scales in Galactic plane cf. extinction. Galaxy photometry: wants Petrosian magnitudes (cf Sloan). Isophotal is not good enough. Kron magnitudes might be more robust for faint galaxies. How much more info should the pipeline provide? Much debate. Difference imaging? Joachim? ? VST (VLT Survey Telescope): break of mirror (!) has not affected ---------- the timescale - April 2004 is still first use. 30% of time will be for public surveys. Each working group should submit to the Call for Ideas from the Workshop in ESO. The deadline for proposals is April 1 2004? Complimentary data must be public - possible problem wrt UKIDSS data. Discussion on what optical data is needed. GCS wants deep i' and z'. GPS wants H_alpha (but won't get it since VST will only do broad-band?). DXS needs lots. LAS ? Andy Adamson Observing tools: Converging on definition of MSB (~0.5 hour). ------------ Software must be ORAC and OFD(?) compatible. See document. Observing tool will select guide star. Proprietary period At moment 18 months private to UK (includes Japanese ------------------ UKIDSS members) and ESO. Some people say this is too long. UKIRT board wants shorter period. Much discussion. Survey WGs should suggest a release plan. In general - suggestion 2 year plan will be world released 1 year after data available to UK/ESO. Grant applications Specific ones not needed for exploitation. Rolling grants ------------------ should cover this, but 2 UKIDSS primary proposals have failed (possibly too early). General feeling is not to panic yet. Skyprobe Extinction measurer (possibly just photometricity?) - good to ~1%. -------- 35" pixels! - internal pixel sensitivity calibration needed. Uses Tycho photometry. Covers 5°x7° on sky. Few £1000, but will involve software development. JAC/ATC not too keen: they think this is already doable with current set up. SJW is very keen. Shanks RGz survey Suggests LAS goes a bit (0.5-1.0 mag?) deeper in overlap ----------------- regions, but general feeling is this should be a private (PATT) proposal. However, might ask Tom Shanks to submit detailed proposal. Ask Mike if C/b wants to host a meeting. If so, contact SJW. Ask SJW to put me on UKIDSS Consortium list. Get hold of UKIDSS first two-year plan. 1. Moon avoidance. Planet avoidance? 2. 12% wasted time - 12% extra to timescale of project? 3. Correlation between seeing and photometric conditions? (Mike says that on LP if it is non-photometric it usually means thumping big cloud. On Hawaii, you often get a lot of high cloud that spoils the photometry, but gives you reasonable seeing).