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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.


 
Table 3.6: Keywords for combining flat field calibration frames
Keyword Content Default Description
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
 


next up previous contents
Next: Combining Sky Frames Up: Preparing Your Calibration Frames Previous: Combining Dark Frames
Petra Nass
1999-06-15