You can search for plates either based on celestial coordinates (J2000) or by searching for patterns in the various database fields. Please see the notes below for important information about how coordinates were assigned to the plates and other search strategies.

• The meta-data for each plate in the database is based solely on the information printed on the envelope and so many fields are missing. As a result, searching for "Hubble" in the Observer field (for example) will yield disappointing results! But the plate ID potentially contains some of this information. Please refer to this guide for search tips using the plate IDs.
• Currently, 81% of the plates have J2000 coordinates. These were determined in one of two ways: 1) the coordinates listed on the plate were precessed from the epoch of observation, if known; or 2) the object name was used to determined approximate coordinates using NED or SIMBAD.
• 15% of plates don't have J2000 coordinates, but do have object strings that were unrecognized by SIMBAD and NED. We are working on identifying these fields, but for now the only way to find these in a search is to use pattern searches (2nd option above). The remaining 4% of plates in the database have no coordinate or object names.
• The information on telescope used for the observations is very sparse, due to incomplete data on the plates and conflicting nomenclature for the plate IDs (for example a prefix 'H' could stand for 'Hooker' or 'Hubble'). We are working to sort this out. In the meantime, only 36% of the plates have reliable telescope data, so if you filter by telescope, keep in mind you are effectively searching only a third of the database.