erosita-forum

Hi,

I want to extract an annular spectra of a large extended source.

Following the advice in the srctool documentation, I should be using EXTTYPE=MAP, and providing an image describing the source spatial extent. For generating an annular spectrum, should the EXTMAP image be of the annular area I want to extract the spectra for, or of the whole source? Would I be generating an incorrect ARF if I provide a larger area in the image supplied to the EXTMAP parameter, than the area I give to the SRCREG argument?

Thanks very much for the help,
Best,
Jessica

Hi Jessica -

I'm off at the moment so can't check the code. I believe that it's only the model in the extraction region which matters. I think you can give a large source model with no problem. You can verify it yourself with a test case, however, and compare the ARFs/exposure.

Cheers

Jeremy