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NOTE: Most of the High Level Science Products are unavailable while unscheduled maintenance is being performed. They will be incrementally restored over the course of this week. We apologize for any inconvenience.


We would like to acknowledge the CASB branch for providing the majority of online information available from MAST. We recommend that users consult the CASB website for the latest information on the Guide Star Catalogs.

Please e-mail questions regarding the Guide Star Catalogs to