The survey masks distributed with the 2dFGRS 100k Data Release are described here and in Colless et al. (2001).

As a user of the mask codes, we request that you observe the following guidelines:

• The code provided here has been written by several members of the 2dFGRS team. Peder Norberg and Shaun Cole (University of Durham, UK) wrote the software used to create the survey masks. If you use any part of this 2dFGRS software, please acknowledge "the 2dFGRS mask software by Peder Norberg and Shaun Cole".
• This code is supplied as-is (i.e. we do not support any modifications to the file mask_compl.f containing the subroutines) and without guarantees - use it with caution and report any bugs.
• Read all of this documentation before trying to use the code!

• Copy the following files:
  • index.html (this file)
  • makefile (for compilation)
  • release.f (the program code)
  • mask_compl.f (subroutines)
  • mask.ngp.dat (completeness mask for the NGP strip)
  • mask.sgp.dat (completeness mask for the SGP strip)
  • mask.ran.dat (completeness mask for the random fields)
  • maglim.ngp.dat (magnitude limit mask for the NGP strip)
  • maglim.sgp.dat (magnitude limit mask for the SGP strip)
  • maglim.ran.dat (magnitude limit mask for the random fields)
  • ngpholes.lis (the excluded regions in the NGP)
  • sgpholes.lis (the excluded regions in the SGP)
• Choose the right compiler for your machine by selecting the right line in makefile. This code has been tested on Sun Solaris, DEC Alpha and PC Linux.

• Given RA and Dec in radians (B1950), it returns the completeness, the magnitude limit and the UK Schmidt Telescope (UKST) sky survey plate number of that particular area.
• When compl = -1, the given position is outside the main 2dF boundary; when compl = -2, the given position is inside an excluded region (a `hole').

The NGP and SGP magnitude limit masks are shown below.

The NGP and SGP redshift completeness masks are shown below.

• Each pixel in the mask maps is 2.8 arcmin on a side. This is much larger than the precision of the 2dFGRS galaxy positions. Hence the masks can indicate that some 2dFGRS galaxies are outside the survey boundary or inside excluded holes due to pixelisation effects, as the masks have been defined in a conservative way.
  • 1252 (NGP=189; SGP=1063; RAN=0) objects of the initial input catalogue are outside the survey boundary according to the survey masks; this is due to pixelisation effects on the survey boundary.
  • 955 (NGP=402; SGP=542; RAN=7) galaxies of the initial input catalogue are inside holes according to the survey masks; in the strips this is due to pixelisation effects on the holes; in the random fields this is due to rounding errors.
  • All 2207 (1252+955) objects not in the survey region have their magnitude limit set to -2 in the magnitude limit masks.
• Please report any serious problem encountered with this software to the 2dFGRS team.