Special Annoucements
Download and review the latest ALCDEF standards PDF.2024 March 4
The site and standard have been updated to distinguish between Pan-STARRS and Sloan ugriz filters and magbands. "Px" stands for Pan-STARRS wile "Sx" stands for Sloan. Magnitudes based on the ATLAS star catalog (Tonry et al., 2008) are Px
The EPOCH keyword has been deprecated and replaced by EQUINOX. Existing programs that generate EPOCH will still work as will upload files using EPOCH. If using a custom program to read/write ALCDEF files, it should be updated to use EQUINOX.
Avoid Duplicate Submissions
A 2025 August 1 review found almost 24,500 duplicate metadata records, i.e., those for the same object with the same session Date/Time, Filter, and MagBand.Check the database before you upload.
If you need to submit updated data, please see the ALCDEF documentation, especially the keyword REVISEDDATA.Duplicate metadata records and their associated lcdata (and compstars, if necessary) will be purged from time-to-time, with the most recent set based on the upload date assumed to be valid.