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- DBObjects store database tables containing the actual data that is used to construct the catalog
- ObservationMetaData objects store information about a particular pointing or observation. This is used to determine what from the DBObject is actually visible. Often, the DBObject will contain objects over the whole sky, but you are only interested in outputting objects that are visible through a specific telescope; the ObservationMetaData contains the information necessary to pare down the DBObject.
- The catalog class combines the DBObject and the ObservationMetaData into a catalog of objects and the desired quantities (RA, Dec, magnitudes, etc.) associated with them.
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