Observing Report ++++++++++++++++ INT WFC imaging: Jan 6-13 2002 Observers: Jonathan Tedds, Pamela Jones (Leicester) Instrument: standard WFC imaging at INT prime focus Filters: U g r i Z Nominal exposures: 1800s 900s 900s 1800s 1800s NO AUTOGUIDER ------------- No autoguider available for WFC so exposures split into 300s integrations and total exposures increased by 50% over normal values. Trailing due to bad tracking minimised by observing targetwith HA<2 if possible and at low airmass. Pointing position: ------------------ 2.5 arcmin RA, 2 arcmin dec offsets from XMM field position as advised Observing conditions: --------------------- 6 Jan: no observing - v.high humidity, high winds + dust 7 Jan: cloudy - seeing 2.5-3" when observing possible - no good data 8 Jan: much cirrus, seeing 3+" - no good data 9 Jan: clouded out 10 Jan: clouded out 11 Jan: 1.5h observing in 2 spells but high humidity, thin cloud, seeing>2" 12 Jan: no observing - 100% humidity all night 13 Jan: GOOD! Early cirrus (seeing 1.5-2") but later clear (seeing 1-1.4" depdt on airmass strongly - dust?) Moon: last Q --> dark Time lost to technical problems: -------------------------------- 7,8 Jan - dome locked out of computer control by day crew requiring duty engineer and causing vignetting of eve flats - rendering useless. all nights - A few trailed images, requiring repeats, due to poor tracking without autoguider. Effect weakly depdt on HA, perhaps more strongly depdt on altitude, but usually masked by poor seeing until final night. 13 Jan - Telescope focus problem (see log) but fixed on resetting. - 4 exposures show double images offset ~15 pixels in EW direction. In each case they are the first exposure at a new position despite all indicators showing tel tracking and WFC idle beforehand - fault report logged. Warning: Exposure times not recorded accurately in logs for flats, stds so check headers (can be at least 5 secs wrong...) Overall little time lost for technical reasons - weather losses dominated! Targets observed ---------------- Target Pri RA DEC Filters r i g z U MS0205.7+3509 1 2 8 50.37 35 25 12.0 - y y y y RXJ0256.5+0006 1 2 56 43.00 0 8 12.0 - - y - y L1448-C 3 3 25 51.63 30 46 0.0 X X * * * SA95-42 2 3 53 53.70 -0 2 33.0 - - - - # CFHT-Pl-12 2 3 54 6.00 23 25 37.5 - - y - y L1641-N 4 5 36 32.36 -6 20 19.0 X X * * * B30731+438 1 7 35 35.74 43 46 20.3 - - y - y 3C192 1 8 5 46.02 24 51 49.9 y y y y * 0952+179 1 9 55 7.30 17 45 31.2 - - y - * DPLeo 0 11 17 26.51 17 59 41.0 - - - - X PG1115+080 0 11 18 26.99 7 47 59.4 y y y y * GPCom 0 13 5 54.02 18 3 2.1 y yt yt * * A1750 0 13 31 4.01 -1 48 0.0 yt * * * * --KEY: Pri 0 = highest then 1,2,3,4....9 y = good data taken (20020113 only this run!) yt= 20020113 data taken into twilight - all i band for GPCom fine, g ok? - = good data already taken pre this run (incl. preceding Jan02 ITP run) X = seeing >2 arcsec, data taken on 7,8,11 Jan 2002 - need repeating * = data required # = data borderline - taken 20020113 but high z and total exposure truncated Biases/Flat fields/Landolt standards: ------------------------------------- A set of 5 biases were taken before the start of observing each day. Flat fields were taken on best efforts basis at the beginning of night. Morning flats impractical due to weather except 20020113 when full eve set. Landolt standards were taken at the beginning of most nights (and the middle of three). Exposure times were roughly checked w.r.t. saturation on at least 1 of recognised standards within field. INT + WFC Issues: ----------------- Seeing shows strong airmass dependency which is probably related to dust - a recurring problem at La Palma! Airmass appears to dominate over any HA tracking problems arising from the absence of the auto-guider for this run except perhaps at v.low airmass <1.1 - to be confirmed. Observe at airmass <1.3 when possible! Things to remember: - always reset focus after focus run - " " pointing of field centre after focus run - " measure seeing, counts etc near centre of chip 4 (min distortion) - " check dome is under remote control at beginning of night - " " dome, focus at desired values on INFODISP before exposure - restart obssys in pink window using >startobssys if SYS hangs after offset - use TCS handset options when object fails to track, typically at 20" offset Use of time and issues ---------------------- The main aims of this run were: - to provide deep imaging for potential fields for upcoming AXIS spectroscopic runs. - to do complete r,i,g,z,U sets for all new fields (in that order). - to complete missing colours in fields already started and/or to redo images that were of poor quality in previous runs. The main fields considered/attempted all have XMM observations made. In practice, given the amount of good imaging time we could only attempt the highest priority fields except where none were available. Due to field selection issues (see below), a small number of fields were imaged at high airmass. This probably only works well if you have ideal conditions. Field selection --------------- In January, the majority of important fields lie towards the beginning of the night or the end with galactic fields (often less suitable optical fields due to extended nebulosity) being more common in the middle. Jonathan Tedds & Pamela Jones, 14 January 2002