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Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/set_backscal.html
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AHELP for CIAO 4.9 Sherpa v1

set_backscal

Context: data

Synopsis

Set the extraction region area

Syntax

set_backscal([id], backscal, [bkg_id])

Description

The set_backscal command sets the extraction region area (backscal). Backscale can be defined as the ratio of the area of the source (or background) extraction region in image pixels to the total number of image pixels. A strict definition is less important than ensuring that the backscale for the source dataset and its associated background dataset are defined the same, because only the ratio of source and background backscale is used in analyses.

  • id - the id of the dataset to use; if not given, uses the default dataset id (id=1 by default, see "ahelp get_default_id")
  • backscal - the backscale value [pixel]
  • bkg_id - the id of the background, if setting the background value; default=None

Example 1

sherpa> set_backscal(2.5e-6)

Set the backscal value for the default dataset to 2.5e-6.

Example 2

sherpa> set_backscal(2, 2e-6)

Set the backscal value for dataset id=2 to 2e-6.

Example 3

sherpa> set_backscal(1, 1e-5, 1)

Set the backscal value for the first background of dataset id=1 to 1e-5.

Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

confidence
set_conf_opt, set_covar_opt, set_proj_opt
data
set_areascal, set_arf, set_bkg, set_coord, set_counts, set_data, set_exposure, set_grouping, set_quality, set_rmf, set_staterror, set_syserror
filtering
set_filter
methods
set_iter_method, set_iter_method_opt, set_method, set_method_opt
modeling
get_par, set_bkg_model, set_full_model, set_par, set_pileup_model, set_source, set_xsabund, set_xscosmo, set_xsxsect, set_xsxset
statistics
set_prior, set_sampler, set_sampler_opt, set_stat
utilities
set_analysis, set_default_id
visualization
image_setregion

Last modified: December 2013
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