sherpa.astro.ui.set_arf(id, arf=None, resp_id=None, bkg_id=None)

Set the ARF for use by a PHA data set.

Set the effective area curve for a PHA data set, or its background.

  • id (int or str, optional) – The data set to use. If not given then the default identifier is used, as returned by get_default_id.

  • arf – An ARF, such as returned by get_arf or unpack_arf.

  • resp_id (int or str, optional) – The identifier for the ARF within this data set, if there are multiple responses.

  • bkg_id (int or str, optional) – Set this to identify the ARF as being for use with the background.

See also


Return the ARF associated with a PHA data set.


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


Load a file as a PHA data set.


Define the convolved model expression for a data set.


Set the RMF for use by a PHA data set.


Read in an ARF from a file.


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 arf parameter. If given two un-named arguments, then they are interpreted as the id and arf parameters, respectively. The remaining parameters are expected to be given as named arguments.

If a PHA data set has an associated ARF - either from when the data was loaded or explicitly with the set_arf function - then the model fit to the data will include the effect of the ARF when the model is created with set_model or set_source. In this case the get_source function returns the user model, and get_model the model that is fit to the data (i.e. it includes any response information; that is the ARF and RMF, if set). To include the ARF explicitly, use set_full_model.


Copy the ARF from the default data set to data set 2:

>>> arf1 = get_arf()
>>> set_arf(2, arf1)

Read in an ARF from the file ‘bkg.arf’ and set it as the ARF for the background model of data set “core”:

>>> arf = unpack_arf('bkg.arf')
>>> set_arf('core', arf, bkg_id=1)