Cannot create grid.csv file

[jcarrick1]

Hi, I have installed spexxy and all its dependencies, but I am having a problem with spexxytools as I can't seem to produce any grid.csv output. Testing out the program, the code seems to run (using the commands from the documentation: spexxytools grid create test_spexxy_fits, where test_spexxy_fits contains a FITS file) and produces no error, but I get no output. Is this a known problem? Apologies if I am missing something. I have tried it with several different FITS formats (the spexxy example in tests/testdata/specta/, an example from ULySS, and another from my own simulations) and get the same result for each.

I am hoping to use spexxy as a python alternative to ULySS, as a way to get stellar parameters from spectra, so any further advice on how to achieve this would be greatly appreciated.

Many thanks.

[thusser]

Did you specify a regular expression for the extraction of the parameters via --from-filename?
You can also create the file manually. It just needs to be a CSV file with Filename column and one column per parameter in the grid, like in the example:

Filename,Teff,logg,FeH,Alpha
PHOENIX-ACES-AGSS-COND-2011/Z+0.5.Alpha=+0.50/lte02300-0.00+0.5.Alpha=+0.50.PHOENIX-ACES-AGSS-COND-2011-HiRes.fits,2300.0,0.0,0.5,0.5
PHOENIX-ACES-AGSS-COND-2011/Z+0.5.Alpha=+0.50/lte02300-0.50+0.5.Alpha=+0.50.PHOENIX-ACES-AGSS-COND-2011-HiRes.fits,2300.0,0.5,0.5,0.5

[jcarrick1]

Ok, it seems I misunderstood the functionality. Doing what you suggested and creating a CSV file manually got me past that initial problem. I think I understand how it works now, I’ve been testing different approaches for different files- Are there any specific guidelines on the format of the FITS files? e.g. what metadata should there be in headers, etc.? Apologies, I know this isn't particularly relevant to the original issue.

Thanks for your help.

[thusser]

No, sorry, no guidelines at the moment. But if there are CRVAL1/CDELT1 keywords in the header, it should be fine. You can simply try to plot a spectrum via "spexxytools plot" to see whether spexxy can read it.

[jcarrick1]

Ah ok, that's good to know. I noticed that not having CRVAL1 was a problem.

Cheers, will close now.