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Last modified: December 2013

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

get_backscal

Context: data

Synopsis

Return the source or background extraction region area

Syntax

get_backscal( [id, bkg_id] )

Description

The get_backscal() function returns the extraction region area of a source or background PHA dataset by data id or bkg_id. The '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. The fact that there is no ironclad definition for this quantity does not matter so long as the backscale for a source data set and its associated background data set are defined in the similar manner, because only the ratio of source and background backscale is used in analyses.

  • id - the id of the data set to use; if not given, uses the default dataset id (id=1 by default, see "ahelp get_default_id")
  • bkg_id - the id of the background to use; default=None

Example 1

sherpa> get_backscal()

When called with no arguments, get_backscal() returns the extraction region area of the source in the default data set.

sherpa> get_backscal()
           9.3626757073098007e-05

Example 2

sherpa> get_backscal(id=2, bkg_id=1)

To return the extraction region area of a background associated with a source data set, the data set ID and background ID must be supplied to get_backscal().

sherpa> get_backscal(2, 1)
           1.872535141462e-05 

Bugs

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

See Also

confidence
get_conf, get_covar, get_int_proj, get_int_unc, get_proj, get_reg_proj, get_reg_unc
contrib
get_chart_spectrum
data
get_areascal, get_arf, get_arf_plot, get_axes, get_bkg, get_bkg_plot, get_bkg_scale, get_coord, get_counts, get_data, get_data_plot, get_dep, get_dims, get_error, get_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror
filtering
get_filter
fitting
calc_stat_info, get_fit, get_stat_info
info
get_default_id, list_stats
methods
get_draws, get_iter_method_name, get_iter_method_opt, get_method
modeling
get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, image_source
plotting
get_split_plot
psfs
get_kernel, get_psf
statistics
get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat
utilities
get_analysis, get_rate
visualization
get_ratio, get_resid, image_getregion

Last modified: December 2013
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