Oct 2003

Mar 2004 - includes analysis of sky variation

Oct 2003 - Old processing

Photometric Grid Oct 2003 - Elixir Tests

"New" processing (June 2004) of Oct 2003 photometric grid. (See below for old Jan 2004 processing of this data.)

Observations - The observations (exposures 723825 - 723965, Oct 22-23 2003) are of a star field at 2000+10, 13 exposures in each of u*g'r'i'z'. The 13 exposures consist of a reference image, 6 shifted images East, and 6 shifted images North. The 6 shifts are 100", 200", 400", 800", 1600", and 3200" (the last doesn't have many stars!!).

Data Reduction - The data was Elixir-processed by J-CC in June 2004. Aperture photometry was done on all objects using SExtractor aperture phot (ap diameter = 25 pix) Bright stars (instrumental mags -12 to -16) were matched astrometrically on the different shifted images using my program 'mscmatch' (run from 'runmsc' with various 'runmsc.filt' files. See notes in mscmatch.f on how to establish shifts (two pass system).

Plots - The plots are separated by filter below. There is a separate sequence of plots for the north shifts and the east shifts. The plots show the difference in magnitude for stars that were observed in the reference and shifted exposure. A few things to note:

u*      g'      r'      i'      z'                               

Photometric Grid Mar 2004 - Elixir Tests

Mar 2004 photometric grid - processed by J-CC in June 2004. See notes above on processing steps.

u*      g'      r'      i'      z'                               

The following files show the variation in sky across the mosaic for the first 6 exposures of each grid sequence. The solid line shows the expected theoretical behaviour (due to scale change) if Elixir were working properly. (See elixskycheck.f) Sky levels were 170du (r'), 230du (i'), and 450du (z'); not enough flux in g and u. not enough sky in g and u.

r'      i'      z'                               

OLD Photometric Grid Oct 2003 - Elixir Tests

This was done back in Feb 2004.

u*      g'      r'      i'      z'