CDDI
to indicate the parent CCD into which the sources were injected. This processing was introduced in DR2.
c4d_[0-9]{6}_[0-9]{6}_ooi_[grizY]_v1\.I\fits\.fz
, where the numeric label corresponds to a rough exposure date-time, "ooi" indicates this is an image file, the band observed is indicated (grizY), a version number for the NOIRLab community pipeline which performs image preprocessing is appended, and the "I" indicates that a synthetic injection has occured. This naming convention follows the convention set by NOIRLab.
Exposure level header containing meta information about the telescope, pointing, etc. For more details, see the NOIRLab (formerly NOAO) documentation. Identical to that in the ooi file (see ooi model).
Injection image created by injecting sources into the image from the CCD specified by the HDU name. Header contains CCD level information from the telescope and is identical to the header for the same CCD without injection in the ooi file (see ooi model). The ZDITHER0 value used to compress the ooi.I file was simply ZDITHER0+=1 relative to the original ooi file (wrapping around at 10000).
An example ooi.I file is linked here: c4d_190503_101947_ooi_Y_v1.I.fits.fz