1D formats for IRFs (ARF, RMF), counts vector (PHA) about gamma-astro-data-formats

[cdeil]

+10 to document this here, especially if there are special keywords or comments to be made when doing XSPEC analysis with OGIP-formatted inputs for TeV astronomy.

My proposal would be to leave https://github.com/gammapy/gamma-astro-data-formats/tree/master/source/irfs alone for now (other people are editing the files there at the moment) and to either add a new folder source/irfs/xspec or source/xspec ... I'm not sure I'd call it 1D IRFs, the PHA files aren't considered IRFs and you want to make notes on that as well, no?

In ~ 1 week when most of the content is accumulated we can discuss proposals to re-structure it better.

[cdeil]

@joleroi - I'll try and finish up most of the data format specs before the HESS FITS data telcon on Wednesday. Do you have time for this one and / or EDISP2D or should I do it?

[joleroi]

I will start with the EDISP2D

[joleroi]

Done, should I start with PHA or are you on it?

[joleroi]

Done

[cdeil]

Thanks!

[cdeil]

@joleroi - I think the most tricky part is EDISP2D and RMF normalisation / interpolation, no?

Can you cross-link the EDISP2D and RMF sections, provide the formula to go back and forth, and say something about normalisation?
For PSF I tried to specify normalisation here:
http://gamma-astro-data-formats.readthedocs.org/en/latest/irfs/psf_table/index.html#normalisation
I don't think it's really useful yet.

If it's not clear what to say about energy resolution normalisation, maybe just leave a TODO for now and make a GH issue?