GCS science verification pages

These pages contain all information relevant to science verification for the UKIDSS Galactic Clusters survey. For the GCS, we requested 8 tiles in each of IC-4665, Upper Sco and Coma Ber along with 16 tiles in Praesepe.

Data (tiles) observed and available for GCS science verification are as follows:

From the minutes of the science verification meeting, recall that the following science verification issues are relevant to the GCS:

Technical topics

• Sensitivity: ALL Done
• Sky brightness and sky limited: LAS, GCS
• Astrometry
  • internal: GCS Done
  • overlap comparison: GCS Done
• Bright stars (ghosts): GCS
• Persistence: ALL
• Cross talk: ALL pipeline correction now implemented
• Bad pixels: ALL

Science topics

• Star counts: ALL Done
• 2MASS match/comparison: ALL Done
• Synthetic colours: ALL

The following GCS-related people have indicated that they will study the stated issues and report back to the first UKIDSS science verification meeting:

• Astrometry (internal; overlap comparison etc.): Nigel Hambly: Report on overlap consistency checks; Report on internal Astrometry
• Astrometry (external): Nicolas Lodieu: result (17 Aug 05)
• Photometry: Nicolas Lodieu: result (17 Aug 05)
• IC 4665 v. 2MASS: Tim Kendall comment
• Survey depth in IC4665 & Coma_Ber: Nicolas Lodieu: result (17 Aug 05)
• Selection of cluster members in IC4665: Nicolas Lodieu: result (13 Sept 05)
• Report on GCS SV2: Nicolas Lodieu (13 Dec 05) See attached file (gcs_sv2_report.pdf) below.

The main point is the following: the colour-magnitude diagrams look very messy in all three GCS clusters (IC4665, Coma Ber, and Upper Sco). Many sources lie to th red and blue sides of the diagrams (see diagrams in the attached report). I have checked a large number of objects for which you can get images and the large majority turn out either (1) to have a nearby companion (case of IC4465) or (2) nothing at the location of the object (case of Coma Ber; see LAS SV2 report as well). I will mention this issue in the meeting help in Edinburgh on 15 Dec 2005.

-- NigelHambly - 06 Jul 2005