Known problems

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

Data products and access

• Photometric redshifts for galaxies The DR1 Catalog Archive Server had a table with photometric redshifts for galaxies, including galaxies fainter than those in the spectroscopic survey. The redshifts still need to be computed and loaded into the database.
• Coverage masks Detailed coverage masks which will allow large-scale structure resarchers to easily calculate power spectrum and related quantities are in preparation.
• IQS/SQS The Imaging Query Server (IQS) and Spectro Query Server (SQS) form interfaces have been re-enginered to use a faster database. They currently do not provide a direct link to the DAS data download form; users need to save .csv files with the necessary information and upload these by hand to the DAS form.

Imaging

• Overestimation of sky levels near bright galaxies
• Bad CCD columns
• Red leaks in u-band
• Problems in u-band sky determination

Object catalogs

• Isophotal radii in DR3 and DR4 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

• 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
• Accuracy of stellar radial velocities