Negative value BITPIX in FIT from Siril

After stacking frames from MP4 file in Siril (ver 1.2.0.-rc1), I get the file FIT with negative value BITPIX = -32. When opening such file, the Siril behaves strangely about autostretch, saving TIF, etc.
Am I doing something wrong or is this Siril’s bug?
moon2_stacked.fits (94.9 MB)

And this is perfectly normal:

Thanks for the info. I didn’t know this definition.
However Siril doesn’t work correctly with this type of FIT with BITPIX=-32. After the file is opened, it looks OK in linear-mode. However opening the Histogram Transformation causes the picture to become black, the graph is not present. When converting to TIF without any correction, the picture is nearly completely black like the levels are shrinked to minimum.

This is the default format for siril. So your issue doesn’t come from this.

So maybe something else is wrong with this file which Siril created but cannot properly work with it. I have no knowledge to indicate it. This is a permanent situation after I stack MP4. I hoped that the FIT-file I attached would help to investigate the problem.

Nothing is attached.
You should use an external website to share file.

Strange because at the beginning of this discussion I can see my attachment and even download it. Anyway if it is not visible for others, then it can be downloaded from here: - Google Drive

Oh sorry it was not in your last message but in the first. Will have a look tomorrow.

OK. This is because all your signal is in the range [0, 255].
You need to check “Output Normalisation” during stacking.

Thanks a lot, it helped :slight_smile:

Lovely shot btw. :+1: