The file headers contain detailed metadata required to interpret the data.
Note: raw data are not currently publicly available.
The raw data are packaged as multi-extension FITS files. A primary header is contained in extension 0 with exposure information that pertains to all 12 detectors. Each CCD has it's own extension, with it's own header, containing the detector image data.
Level-1 (Single Exposures)
The processed single frame images are single FITS files, one per CCD. The catalog files are FITS binary tables. Each catalog file has it's own header. However, they additionally have appended an additional extension, after the table extension, which contains the original header of the parent flux image.
The image data is a single FITS file. It contains basic WCS information as well as some information about the coaddition process. After the image extension there are additional extensions which contain full copies of the headers of each input image that went into the coaddition. The catalog files, like the Level-1 data, are binary FITS tables.