erosita-forum

Hi Brandon All radec2xy does is recalculate the X and Y coordinates to be centred on that position in the event file. By default, it should be the centre of the sky tile. If you'd like to make an image from the event file, then evtool is what you should use. It's a bit easier to use radec2xy to set ...

Hi Brandon It's not very clear what you want to do. Can you explain what you want to achieve from the start? Why do you need to have an event file centred on a source? Is it for making images or source extraction? If your source covers multiple tiles, you'll need evtool to merge them. If you want to...

Hi Jorge This seems like it ran out of memory to me. Is this Linux? If so, you could try running dmesg (may need sudo) and see whether the OOM Killer (out of memory killer) killed the process. If so, you'll need a machine with more memory or swap, or use smaller regions. It could also be quotas that...

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

Dear Katharina Sorry for the delay. Ian's away at the moment, so I will reply. We've done some investigation to check that expmap is doing what we expect. The behaviour is * If withweights=yes, then the merged map is the effective on-axis exposure time that TM0 would have, no matter which TM modules...

Hi Joe Yes, it's because the background spectra are accumulated during the good time intervals (GTIs) of the source. The manual says Please note that by default any background region is extracted using the same GTIs as the source. If the source region is large, this means that only a limited part of...

PS In Xspec, I suggest the "setplot rebin" command to visualise spectra with low numbers of counts with low grouping. e.g. "setplot rebin 10 50", to rebin for display to S/N=10 and a max of 50 channels. This doesn't affect the fit, but allows you to visualise the fit.

You need to look at brighter sources to get better spectra! For very faint sources you will have to make some strong model assumptions, for example where you freeze your parameters or add strong priors. You might only get a flux depending on model. Take a look at this advice: https://asd.gsfc.nasa.g...

Hi Matteo

If you're making merged exposure maps, the exposure time is the equivalent exposure for the *on-axis* combined eROSITA effective area.

You can take the effective area at a particular energy from the ARF file here: https://erosita.mpe.mpg.de/dr1/eSASS4DR ... R1_arfrmf/

Cheers

Jeremy

Dear Joe I would need to see a more complete description of how you are using srctool to understand the problem better. However, I can give some comments: The exposure time given by srctool isn't the same as in exposure maps - it is more of an on-time. See the docs. I would not use the rates from sp...