Depending on the data format, this step and the subsequent step (interleaving and coadding, see Interleaving and Coadding ) may be swapped. If the flat frame and data frame were both taken with the same interleaving, then flat-fielding is done after interleaving. Otherwise, flat-fielding is done first. See Flat Fields for information on how spectroscopic flat-fields are created.
Flat-fielding is done by a straight division of the data frame by the
appropriate flat-field calibration frame.
[_DIVIDE_BY_FLAT_, _FLATFIELD_COADD_INTERLEAVE_]
ORAC-DR -- spectroscopy data reduction