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
PHACrateDatasetfor crates, as used by CIAO, or a list of AstroPy HDU objects.
use_errors (bool, optional) – If
Truethen the statistical errors are taken from the input data, rather than calculated by Sherpa from the count values. The default is
bkg_id (int or str, optional) – The identifier for the background (the default of
Noneuses 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.
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)