Error loading compressed FITS files

[Rafael Barbera Cordoba]

I was trying to follow this astrobin thread to evaluate the backfocus adjustment on my coma corrector. I'm using KStars/Ekos to capture the images, so I've used the debug menu on Ekos to activate the option to save each image on a focus sequence. I've a folder filled with images with the focus position on them but they are not readable. The FITS generated by Ekos on the debug menu are compressed and ASTAP is not able to open them. Are there any way to transform this files keeping the header information? I've tried to use SiriL to perform the conversion from compressed FITS to uncompressed ones, but the focus position field is striped away.

Regards

[han.k]

ASTAP will read compressed FITS files as long they have the extension .fz

1) Install the decompress/compress program by sudo apt-get install libcfitsio-bin
2) Rename extension of all files to .fz

I will have a look if ASTAP can detect compressed files directly but it is not the case yet. .fz is required.

Probably you could uncompress them with the command-line "funpack" but via ASTAP is easier.

See attached screenshot. The focuspos is read.

Han

[han.k]

!! Change the extension of the compressed file to .fits.fz. The unpack program will then change it to .fits. If you change the extension to only.fz, then you will end up with a files without extension. Not a big problem but you have to add the extension again.

Han

[Rafael Barbera Cordoba]

Thank you @han.k. It was not so easy because I'm running ASTAP on macOS. Anyway, I was able to find, compile and install funpack, so I can now uncompress the files before loading them on ASTAP. Thanks you.

[han.k]

The next version Kstars will add the fits.fz extension making it compatible with ASTAP:

https://bugs.kde.org/show_bug.cgi?id=461103