Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: data


Load the background from a file and add it to a PHA data set.


load_bkg(id, arg=None, use_errors=False, bkg_id=None)

id - int or str, optional
use_errors - bool, optional
bkg_id - int or str, optional


This will load the PHA data and any response information - so ARF and RMF - and add it as a background component to the PHA data set.


Example 1

Load a source and background data set:

>>> load_pha('src.pi')
read ARF file src.arf
read RMF file src.rmf
>>> load_bkg('src_bkg.pi')

Example 2

Read in the background via Crates:

>>> bpha = pycrates.read_pha('src_bkg.pi')
>>> load_bkg(bpha)

Example 3

Create the data set from the data read in by AstroPy:

>>> bhdus ='src_bkg.pi')
>>> load_bkg(bhdus)


The parameters for this function are:

Parameter Definition
id The identifier for the data set to use. If not given then the default identifier is used, as returned by `get_default_id` .
arg Identify the data to read: a file name, or a data structure representing the data to use, as used by the I/O backend in use by Sherpa: a phacratedataset for crates, as used by CIAO, or a list of AstroPy HDU objects.
use_errors If True then the statistical errors are taken from the input data, rather than calculated by Sherpa from the count values. The default is False .
bkg_id The identifier for the background (the default of none uses the first component).


The function does not follow the normal Python standards for parameter use, since it is designed for easy interactive use. When called with a single un-named argument, it is taken to be the `arg` parameter. If given two un-named arguments, then they are interpreted as the `id` and `arg` parameters, respectively. The remaining parameters are expected to be given as named arguments.


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

See Also

dataspace1d, dataspace2d, datastack, fake, load_arf, load_arrays, load_ascii, load_bkg_arf, load_bkg_rmf, load_data, load_grouping, load_image, load_multi_arfs, load_multi_rmfs, load_pha, load_quality, load_rmf, load_staterror, load_syserror, load_table, pack_image, pack_pha, pack_table, unpack_arf, unpack_arrays, unpack_ascii, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf, unpack_table
get_default_id, list_bkg_ids, list_data_ids
add_model, add_user_pars, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
save_arrays, save_data, save_delchi, save_error, save_filter, save_grouping, save_image, save_pha, save_quality, save_resid, save_staterror, save_syserror, save_table