tiRandom Files

The tiRandom files contain random ra/dec catalogs, with information on which sector and boundary region each random point falls in. Each point has the parameters:

• ra: right ascension, degrees
• dec: declination, degrees
• overlap: which sector (overlap region) the point falls into
• firstboundary: which boundary region it falls into

The proper way to use these files in conjunction with the LSS samples in the lss/ is as follows.

• Pick a the next point from the file.
• Pick a random redshift within about 0. to 0.4 or so. Remember this should be uniformly distributed in VOLUME! So given your cosmology you should pick a random enclosed VOLUME between V(0) and V(0.4), and then invert to get the redshift.
• Given the redshift and the firstboundary index, check the czselfunc.sample*.[firstboundary].dat file. Pick a random number from 0 to 1.
  • if it is greater than the czselfunc number, throw away the point entirely and start at the beginning.
  • if it is less than that number, continue
• Now check f_gotten from the osampling file for your sample, for the appropriate sector (overlap). Pick a random number from 0 to 1. Again:
  • if it is greater than the osampling number, throw away the point entirely and start all the way at the beginning.
  • if it is less than that number, continue
• When you reach this point, entire that position (ra, dec, redshift) into your random sample.

For reference, here is the fits header:

XTENSION= 'BINTABLE'                                                        
BITPIX  =                    8                                              
NAXIS   =                    2                                              
NAXIS1  =                   24                                              
NAXIS2  =              1000000                                              
PCOUNT  =                    0                                              
GCOUNT  =                    1                                              
TFIELDS =                    4                                              
TFORM1  = '1D      '                                                        
TTYPE1  = 'ra      '                                                        
TFORM2  = '1D      '                                                        
TTYPE2  = 'dec     '                                                        
TFORM3  = '1J      '                                                        
TTYPE3  = 'overlap '                                                        
TFORM4  = '1J      '                                                        
TTYPE4  = 'firstBoundary'                                                   
END