Known problems

The following is a clearinghouse of known issues and caveats with links to detailed descriptions or workarounds where available.

Imaging

• Incomplete and/or inaccurate photometry at low galactic latitudes
• Overestimation of sky levels near bright galaxies
• Bad CCD columns
• Red leaks in u-band
• Problems in u-band sky determination

Object catalogs

• Proper motion errors are not correct.
• Isophotal radii in DR3, DR4, and DR5 are given in pixels, not arcseconds
• SDSS and AB magnitudes
• Sky brightness values are extinction-corrected
• Sky brightness values are given in maggies, not magnitudes
• Object counts in tsField files are not meaningful
• A few runs processed with slightly older version of photo.

Spectroscopy

• Bug in Synthetic magnitude tabulation
• Bug in SEGUE primtarget flag, values truncated
• Offset of 0.35mag in spectrophotometry on 28 plates in DR6's new spectral reductions
• DR6 has improved accuracy of stellar radial velocities
• Check redshift status (zStatus) for reliability of redshifts
• Zero equivalent width emission lines
• Main survey spectra without tsTargets files or target/targetInfo entries in CAS
• Treatment of galactic extinction correction in spectra
• Plates with not-quite-perfect spectrophotometry
• Mismatches between spectra and photometric data
• Reliability of galaxy velocity dispersion measurements
• Bonus plates with coverage extending beyond formal survey area
• TileRun 60 boundaries in the DR5 CAS are inaccurate.