Combining Flat Fields

  In combining the flat field frames the filter type is of importance. Hence, the combining command will check for consistency of the keyword containing the filter type. The combining input parameters can be set up in the flat parameter table, similar to the dark frames. Table 3.6 show the default keyword settings.

 

CCD_IN input name ? table of input frames

FF_TYP descriptor value * exposure type to check, if any

FF_SIG yes|no no create sigma image

FF_MET comb. method avsigcl type of combining operation

FF_DEL yes|no no delete cal. frames afterwards

FF_STA mean|median|mode mode correct. by Mode/Median/Mean

FF_EXP yes|no yes scale by exposure time

FF_SCA yes|no no scale by MMM

FF_OFF yes|no no add offset obtained from MMM

FF_WEI yes|no yes use a weighted average

FF_SEC area [<,<:>,>] area for computing MMM

FF_RAN real,real -99999,99999 valid pixel range

FF_CLP real 3.,3. low/high sigma clipping factor

FF_NUL real NULL(2) value for rejections