Hi,
I have several thousand images as FITS files (scans of old glass plates) and I would like to use
astrometry.net to get WCS info for them. My approach has been to write a Python script that uses astroquery.astrometry_net. I have installed photutil and I'm calling solve_from_image in my script like this:
wcs_header = ast.solve_from_image(fits_file,
submission_id=submission_id,
downsample_factor=2, parity=2,
scale_units='degwidth', scale_type='ul', scale_lower=0.1, scale_upper=180.0)
The problem is that I can never get a successful outcome from the solver this way (it always times out). However, I can upload one of my images and get a solution fairly quickly that way. I have chosen the parameters in the above call to match those which seem to be the default for an image upload so I could compare the log files but this has not really helped me and I've decided I need an expert!
My image upload is job 8297115 and my attempt via my python script is job 8297662
I've tried setting values for FWHM and the plate scale but this has made no difference. I suspect that photutil might be finding too many stars or else is finding sources that are really noise, but I have not been able to change the outcome by fiddling with parameters like detect_threshold and FWHM.
I tried installing sextractor and then using "use_sextractor=True" but this made no difference (I think I have realised that this setting only applies to image uploads?)
I assume that my approach is valid - i.e. that NOT uploading several thousand images is a good idea and that trying to locally extract sources is the best way to go. Please let me know if there is a better way I could or should be doing this. Each image is about 200MB.
Regards,
Bill Roberts