These files can be thought of as an extended log of the observations.  The 
additional quality control information is derived from the catalogues.

#01 Run No.  - orignal run number generated by observing system

#02 CCD No.  - note the format changes slightly after August 1999

#03 Obj Name - object name which should be a close approximation (sic!) to 
               the catalogue object name

#04 RA       - where the telescope thinks it was pointing in RA and

#05 Dec      - in Dec, if nominal pointing used these are centre of CCD#4

#06 Equinox  - of the coordinates above

#07 AM       - airmass at mid-point of observation ie. sec(z)

#08 PA       - position angle of PF rotator in degrees, 180 is the default
               and also corresponds to the www layout shown at
               http://www.ast.cam.ac.uk/~wfcsur/ccd.html

#09 Date     - actual date of observation

#10 UT       - well.....UT of observation

#11 Exp      - actual exposure time in seconds

#12 Filter   - generally uppercase are the standard glass filters, lower
               case are the SDSS equivalent set, and KPB is Kitt Peak B.

#13 Seeing   - estimated seeing, ie. FWHM in arcsec obtained using all
               appropriate, ie. not saturated and reasonable s:n, stellar 
               images.  Provisional survey upper limit for acceptability
               is (generously) 5 pixels or 1.67 arcsec.

#14 Sky      - sky brightness in counts/pixel.  To convert to magnitudes
               per sq arcsec apply the following formula, but code it more
               efficiently !,

               Sky SB = ZP - 2.5*log10(counts/pixel) + 2.5*log10(Exp)
                           + 5.0*log10(0.3334)

               NB.  the effect of non-linear radial distortion terms is 
               negligible. 

#15 Noise    - robust rms noise estimate at general sky level in counts/pixel
               to convert to 1-sigma magnitudes/sq arcsec 

               Sky NB = ZP  - 2.5*log10(counts/pixel) + 2.5*log10(Exp)
                            + 2.5*log10(0.3334)

#16 Ellipt   - average ellipticity of stellar images using all appropriate,
               ie. not saturated and reasonable s:n, objects.  If greater
               than 0.20 implies significantly trailed images.  An
               average ellipticity of <=0.20 is the provisional survey 
               quality control limit ( ellipt = <1 - b/a> )

#17 APcor    - aperture correction in magnitudes to convert median seeing 
               radius aperture flux (ie. 2.3 arcsec diam) to total magnitude 
               for stellar-like objects.  Naturally highly correlated with 
               measured seeing

#18 Comments - visual inspection or log comments "x" means rubbish the rest
               is why