specsky

Name

specsky– Sky Subtract 2-D spectroscopic data

Usage

specsky images outimages outpref (method) (section) (thresh) (clobber) (logfile) (verbose)

Parameters

images
String. List of FITS images to prepare. Data can be provided as a comma-separated list, or a string with a wildcard (e.g. ‘images=S20061210*.fits’), or a foreign file containing an ascii list of image filenames. For the ascii list option, the filename containing the list must be provided preceded by a ‘@’ character, e.g. 'images=@listoffiles.lis‘. The list can contain data files from multiple SALT instruments.
outimage
String. A list of images. Data can be provided as a comma-separated list, or a string with a wildcard (e.g. ‘outimages=rS20061210*.fits’), or a foreign file containing an ascii list of image filenames. For ascii list option, the filename containing the list must be provided preceded by a ‘@’ character, e.g. 'outimages=@listoffiles.lis‘. This list must be of the same size as the images argument list.
outpref
String. If the outpref string is non-zero in length and contains characters other than a blank space, it will override any value of the outimages argument. Output file names will use the name list provided in the images argument, but adding a prefix to each output file defined by outpref. An absolute or relative directory path can be included in the prefix, e.g. ‘outpref=/Volumes/data/p’.
(method)
String. The method to use for sky subtraction. Currently, the only option is ‘normal’ where lines will be extracted from the region specified by section to be subtracted.
(clobber)
Hidden boolean. If set to ‘yes’ files contained within the outpath directory will be overwritten by newly created files of the same name.
(logfile)
String. Name of an ascii file for storing log and error messages from the tool. The file may be new, or messages can also be appended to a pre-existing file.
(verbose)
Hidden Boolean. If verbose=n, log messages will be suppressed.

Description

SPECSKY will subtract sky regions from the data. The task currently only has one mode of operations which is ‘normal’. In this mode, the task estimates the skylines from a region in the image specified by section. These skylines will then be subtracted from the rest of the image.

EXAMPLES 1. To subtract sky lines with specsky:

--> specsky images='pmbxpP*.fits' outimages= outpref='r'
method='normal' section='[1200:1500]' logfile='salt.log'

Time and disk requirements

Individual unbinned raw full-frame RSS files can be 112MB in size. It is recommended to use workstations with a minimum of 512MB RAM. On a linux machine with 2.8 Ghz processor and 2 Gb of RAM, one 2051x2051 image in 0.15 sec.

Bugs and limitations

The sky subtraction algorithm needs to be improved as it is very simple and does not account for a number of effects.

Send feedback and bug reports to salthelp@saao.ac.za

See also

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