sherpa.astro.ui.load_multi_arfs(id, filenames, resp_ids=None)

Load multiple ARFs for a PHA data set.

A grating observation - such as a Chandra LETGS data set - may require multiple responses if the detector has insufficient energy resolution to sort the photons into orders. In this case, the extracted spectrum will contain the signal from more than one diffraction orders.

This function lets the multiple ARFs for such a data set be loaded with one command. The load_arf function can instead be used to load them in individually.

  • 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.

  • filenames (iterable of str) – An array of file names.

  • resp_ids (iterable of int or str) – The identifiers for the ARF within this data set. The length should match the filenames argument.

See also


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


Load multiple RMFs for 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 two arguments, they are assumed to be filenames and resp_ids, and three positional arguments means id, filenames, and resp_ids.

The minimum_energy setting of the ogip section of the Sherpa configuration file determines the behavior when an ARF with a minimum energy of 0 is read in. The default is to replace the 0 by the value 1e-10, which will also cause a warning message to be displayed.


Load three ARFs into the default data set, using response ids of 1, 2, and 3 for the LETG/HRC-S orders 1, 2, and 3 respectively:

>>> arfs = ['leg_p1.arf', 'leg_p2.arf', 'leg_p3.arf']
>>> load_multi_arfs(arfs, [1, 2, 3])

Load in the ARFs to the data set with the identifier ‘lowstate’:

>>> load_multi_arfs('lowstate', arfs, [1, 2, 3])