ISGRI spectrum

The role of a catalog

It is important to understand that the INTEGRAL instruments are equipped with coded mask. It is tus necessary to specify a sky model to extract spectra or light curve. If you do not supply a catalog, the infrastructure will first produce an image and take all the source, with possible contamination from spurious detections. See the IBIS user manual for details.

It is thus strongly encouraged to prepare explicitly a catalog through an image, edit the catalog and then submit the spectral extraction. A common practice is to make an image from a subset of science windows by adjusting the "Maximum number of ScWs" parameter and then extract a spectrum from all science windows. In the platform, a defaul binning is applied to the spectrum.

Note that all this can be done also using the python API, see this notebook.

Spectral extraction from a catalog

Suppose that you have succesfully extracted an image and get to the point

you should remove the spurious "NEW_1" introduced by the OSA software by selecting it and click on "delete"

The click on use catalog, select spectrum on the left and hit submit (Energy Min and Energy Max parameters are ignored).

You will receive a message like the one reported here and wait for a second one with the report of completion.

At his point you can click or the url, click on the "done" button of the popup and you will reach a page like

You can make an online fit for any source with a powerlaw (a known issue prevents to use other models) and download the spectrum to make your own local fit.

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