The second stage in the DEEP2 pipeline produces spSlit.xxxx.nnnB.fits and spSlit.xxxx.nnnR.fits. These files contain the raw science data and information pertaining to the 2d-bspline sky modeling. Reading one of these files can be done via the mrdfits command (this routine is part of the GODDARD IDL/FITS library and is contained in the SDSS IDLUTILS package). For example, the command     IDL> ss = mrdfits('spSlit.2200.004B.fits', 1) reads the first extension of this calibSlit file into the variable s. To find out what ss contains, execute     IDL> help, s, /str which will list the IDL structure 'tags' showing the type and the size of each tag. Detailed defintions of the spSlit structure tags, pertaining to the 1st extension of the spSlit files, are given in below...

FLUX:	the raw flux, in units of e-/hour, for each slitlet.
IVAR:	the inverse variance of the flux, including read-noise. IVAR=0 in bad pixels (infinite variance).
SKYROW:	tells whether a row went into the b-spline sky model. We exclude rows around objects and at the edges of slits.
SLITWIDTH:	gives the width of the slitlet in units of arcseconds. The DEIMOS pixel scale is 0.117371 arcsec/pixel.
MASK:	a bitmask with the following definition (defined in deimos_spslit.pro): Bit 0 - flatmask pixel not flat-fielded Bit 1 - badpix bad column, CTE issue, etc. Bit 2 - specmask no data went into this pixel (when rectified) Bit 3 - vigpix vignetted pixel Bit 4 - pixmap bad pixel in the pixmap (e.g. on deep dust grain) (note that only bits 0,1 are set in the calibSlit* files)
SLITFN:	inherited from calibSlit file.
LAMBDAX:	inherited from calibSlit file.
TILTX:	inherited from calibSlit file.
DLAM:	inherited from calibSlit file.
INFOMASK:	a bitmask with the following definition (defined in deimos_spslit.pro): Bit 0 - nearvigmask pixel is >0% vignetted Bit 1 - bsplinemask pixel rejected in bspline process Bit 2 - nobsplinemask bspline is undefined for pixel