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Combining Bias Frames

Combination of the bias frames is straight forward: filters used and integration times do not play a role, and in most cases the bias frames can be treated with the same weight. The default keyword setting for the bias combining is displayed in Table 3.4.


 
Table 3.4: Keywords for combining bias calibration frames
Keyword Content Default Description
CCD_IN input name ? table of input frames
BS_TYP descriptor value * exposure type to check, if any
BS_SIG yes|no no create sigma image
BS_MET comb. method maxrej type of combining operation
BS_DEL yes|no no delete cal. frames afterwards
BS_STA mean|median|mode mode correct. by Mode/Median/Mean
BS_EXP yes|no no scale by exposure time
BS_SCA yes|no no scale by MMM
BS_OFF yes|no no add offset from MMM
BS_WEI yes|no yes use a weighted average
BS_SEC area [<,<:>,>] area for finding MMM
BS_RAN real,real -99999,99999 valid pixel range
BS_CLP real 3.,3. low/high sigma clipping factor
BS_NUL real NULL(2) value for rejections
 


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