MKDARK

Name

mkdark

Purpose

Collect and combine CCD dark frames into a superdark frame

Description

The files are assumed to be named as 'root'NNN where 'root' is the
root of the file name that you supply and NNN is a three digit number.
If your file name has an imbedded '.' then add it to the root.
The specified range of files are all read in from FITS files. Then each
image has the overscan mean subtracted (if desired), cropped (as indicated),
and then the input bias image is subtracted. These images are then
normalized to counts per second and then averaged. The averaging
is done with AVGCLIP.PRO which does a robust average of the image
stack so that cosmic rays or other transient image defects are eliminated.
When done, the resulting dark image is returned to the caller and the image
is saved to a FITS file with the specified output filename.

Calling Sequence

mkdark,root,outsuf,start,nframes,bias,dark

Inputs

root - Root of the file name (you must include . in the name).
outsuf - The suffix of the final output file.
start - First frame number to read (integer or long).
Start can also be a vector of explicit frame numbers to load.
In this case, nframes need not be specified and in fact will
be ignored.
Additionally, start can also be a string array containing the
file names of all files to be read. In this case, set nframes
to 0 or someother innocuous integer. Exclude is treated
differently. In this case, exclude is a vector of the same
length as start and is 0 if the file is to be used, 1 if not.
nframes - Number of frames to average.
bias - Name of bias frame image to subtract from each raw dark.

Optional Input Parameters

Keyword Input Parameters

CROP = region of original image to save, default=no cropping.
[x1,x2,y1,y2]
DDIR - Path to the raw data, default = ''
EXCLUDE - Optional vector of image numbers that should be excluded from
average. Default is to include all frames.
EXPKEY = String - FITS keyword to read to get exposure time, default = EXPTIME
OVERSCAN = column overscan region to use for frame bias level,
default=no overscan subtraction.
RDNOISE - Read noise of CCD, e-/DN, default=10

Outputs

dark - Final robust averaged dark image scaled to counts per second.

Keyword Output Parameters

Common Blocks

Side Effects

Restrictions

Procedure

Modification History

95/03/09 - Initial crude version written, Marc W. Buie, Lowell Observatory
95/08/30, MWB, added OVERSCAN and CROP keywords
95/11/22, MWB, add EXCLUDE keyword
99/06/10, MWB, added EXPTIME keyword and added documentation.
2001/02/23, MWB, added option to provide input file list. Also, added
functions to make it consistent with mkbais,mkflat.
2005/03/10, MWB, added DDIR keyword, converted bias input to string
2006/07/14, MWB, added RDNOISE keyword