set_exposure

Context: data

Synopsis

Change the exposure time of a PHA data set.

Syntax

set_exposure(id, exptime=None, bkg_id=None)

Description

The exposure time of a PHA data set is taken from the exposure keyword in its header, but it can be changed once the file has been loaded.

Examples

Example 1

Increase the exposure time of the default data set by 5 per cent.

>>> etime = get_exposure()
>>> set_exposure(etime * 1.05)

Example 2

Use the EXPOSURE value from the ARF, rather than the value from the PHA file, for data set 2:

>>> set_exposure(2, get_arf(2).exposure)

Example 3

Set the exposure time of the second background component of the 'jet' data set.

>>> set_exposure('jet', 12324.45, bkg_id=2)

PARAMETERS

The parameters for this function are:

Parameter	Type information	Definition
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` .
exptime	num	The exposure time, in seconds.
bkg_id	int, str, or None, optional	Set to identify which background component to set. The default value ( none ) means that this is for the source component of the data set.

Notes

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

Bugs

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