The F22I catalog: patching the hole

This page describes the update to the  F22I wide-field catalog.
Why is this necesary?
The original F22I catalog was missing some data near the centre of the field. When the original catalog was being produced, it would have been impossible to reduce the missing data correctly in a timely manner. Since the F22I catalog was needed shortly for a VIMOS commissioning run, it was decided to leave out the data for the time being and add it afterwards.

The data has now been reduced. Note that the data in "the hole" is of lower quality than the rest of the field. Tests show significant (~0.1 mag) differences in magnitudes measured from the new data with respect to the old. These shifts are similiar in nature to the CCD to CCD variations noted earlier (see this webpage), but greater in magnitude. As with the earlier problem, this photmetric problem has simply been ignored, pending a greater understanding of its nature. 


The patch:

There are two parts to the patch. The first is the removal of the objects that are already in the VIRMOS database, the second is the addition of new objects. This is potentially a slightly messy task because of the irregular shape of the hole. The hole in effect been enlarged and made rectangular. All the entries in the VIRMOS database within the following region are affected:

22:18:01.44 < RA  < 22:19:10.56
00:09:24.03 < Dec < 00:39:54.702

Or in decimal degrees:

334.506  < RA  < 334.794
0.156675 < Dec < 0.665195

To be removed:
The entries to be deleted from the VIRMOS database are in the file:

This file is in VIRMOS database output format and contains the following columns:

The ID number is the VIRMOS database numbering scheme.

To be added:
In the naming scheme for the four quadrents of the original catalog (described here) files where called F22I??... where the ?? were one of "se", "sw", "ne", or "nw" for the South-East, South-West, North-East and North-West quadrents respectively. Following this style we have "ce" for "centre". All the files are in:

  • The catalog for the centre patch. It is in SExtractor ASCII_HEADER format. The ID numbers are sequential starting at 5000001.
  • F22Ice.xy: X and Y coordinates with respect to the full original image. The format is 3 columns ID X_IMAGE Y_IMAGE
  • The masks, one per line (RA_1 Dec_1 RA_2 Dec_2) in decimal degrees) Objects inside one of these boxes  (ie. RA_1<RA<RA_2 and Dec_1<Dec<Dec_2) are corrupted in some way, be it contamination from a bright source, satellite trail, bad fringing or another source. This file has been updated to include the boxes for the centre.
  • F22Icegwyn.flags: Flags for the objects in One line per object in, 6 columns: 
    • ID (matches first column of
    • overall flag = (star flag)+2*(box flag)+4*(mask flag)+8*(bright flag)
    • star flag: 1 if the object is point source
    • box flag: 1 if the object is outside the image boundaries
    • mask flag: 1 if the object is inside a box (i.e. contaminated)
    • bright flag: 1 if the object is brighter than IAB  = 17.5 (MAG_AUTO),
    Following this scheme, usable galaxies have an overall flag of 0, usable stars a flag of 1. Non usuable objects have a flag of 2 or greater. Star-galaxy separation was non-trivial due to seeing variations accross the field. See the full discussion. 
  • F22Icehjmcc.flags: Flags for the objects generated in the same manner as described by Henry McCracken on his webpage with the exception that I have used my adaptive method of star-galaxy separation.
  • Sub-images: Only the centre image is given here.
    • F22Ice.fits (179Mb)
    • F22Iceb4.fits (11Mb): same, binned 4x4
    • F22Ice.weight.fits: weight image
  • F22I.log: Detailed log of how the images and catalogs were created.