Extracting sources
Extracting sources — point or extended — will probably be necessary at some point during your analysis of your data. There are a number of ways to do this, which you use depends on your science goals.
(A)
Identify the spaxels that contain your interesting information (e.g. by looking at the data in a visualisation tool), and then manually extract those spaxels. You may be able to use the visualisation tool for this, if not then all you need to do is identify which aperture numbers you wish to extract (using your eyes, the displayed data, and the position table) and then use IRAF or IDL to pull out of the RSS fits file or cube the relevant spectra/spatial region.
(B)
For more sensitive extraction of point-sources you may wish to perform a PSF-based extraction (see below). This is something to consider if your spatial sampling is not perfect and you wish to improve the flux performance of your extraction (i.e. to mitigate the effects of bad samping, such as discussed for Integral). It is also worth considering if you are working on a faint point source and wish to improve the SNR of the extracted spectrum, if you need to separate out a point source from background emission or if you want to improve the accuracy of extracting the spectra of two distinct sources that are very close together. For any type of extraction you will have better results if you have a even and contiguous spatial sampling.
As with imaging, the instrumental spatial PSF is set by a combination of the instrument+telescope and the seeing during your observing. Spaxels that are separated from each other by less than the PSF are not independent of each other.
We hope to include more information on this technique at a later date, and scripts for doing this type of work. However, if anyone has done this before, in particular working on separating galaxy hosts from the (AGN) cores, could they please write something here?
PSF fitting techniques
This is a section we are still working on. Keep you eyes peeled!
