sherpa.astro.ui.load_bkg(id, arg=None, use_errors=False, bkg_id=None)

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

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.

  • id (int or str, optional) – 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 (bool, optional) – 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 (int or str, optional) – The identifier for the background (the default of None uses the first component).

See also


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


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


Load a PHA data set.


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.


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')

Read in the background via Crates:

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

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

>>> bhdus = astropy.io.fits.open('src_bkg.pi')
>>> load_bkg(bhdus)