The SWIFT BAT Software Guide Version 6.3 30 ... - HEASARC - Nasa

D.3. BATCLEAN 117
• 9 = Detector on right (+X) side of sandwiches: constant,
• 10 = Right side detectors: proportional to X,
• 11 = Detectors on front (-Y) side of sandwiches: constant,
• 12 = Front side detectors: proportional to Y,
• 13 = Detectors on back (+Y) side of sandwiches: constant,
• 14 = Back side detectors: proportional to Y,
The code creates a background exposure map based on the model above (which can be optionally
output using the backexp parameter). In addition the user can supply his own background model
to be fit in addition to or in place of the standard background model.
The tool then uses a singular value decomposition method to fit the source exposure and
background exposure maps to the data from the DPI. The coefficients from the fit are written
to the output file as keywords.
The fit coefficients are then used to create a model background DPI. This is then subtracted
from the original input DPI to produce a cleaned DPI. The code writes keywords giving the fit
parameter for each background parameter (simple plus user supplied) and source parameter that is
fit. These keywords are BGPARnn for background and SRPARnn for sources. The number nn goes
from 0 to the total number of parameters, starting with the hard-coded background parameters.
D.3.4 PARAMETERS
infile [filename ]
Input file name. The name of the input DPI file. This is expected to be an image array
with dimensions equal to the number of detector columns by the number of detector rows
(set to 286 X 173). If there are multiple BAT DPI image extensions then all are cleaned and
multiple cleaned images are written to the output file.
outfile [filename ]
Output file name. This will be written in the DPI format. The default is to write out the
cleaned image, but other outputs can be selected using the outversion parameter. Precede
the output file name with an exclamation point, “!”, (or “\ !” on the Unix command line),
to overwrite a preexisting file with the same name (or set the clobber parameter to YES).
incatalog [filename ]
Input source catalog. The format of the catalog file is that output by the BAT tool batcelldetect.
In particular the catalog must contain columns “IMX,” “IMY,” “CATNUM,” (or
“SOURCE ID”), “NAME,” and “SNR.” The tool reads the source position in BAT image
coordinates from this file and uses the source position to forward project a model of the
source flux onto the focal plane. This parameter may be omitted or set to “NONE” if only
background cleaning is required (i.e., the srcclean parameter set to “NO”). The SRPARnn
keywords giving the fit parameter for each source contain the source name in the comments
field. Allowed extension names for incatalog are “BAT CATALOG” (default of batcelldetect),
“TRIG SOURCE” (BAT on-board catalogs) and “INPUT CATALOG.”