FITS Header Time

It looks like the time is only accurate to the nearest second when I use my QHY 268M camera. There are a lot of decimal places but all populated with 0, e.g.:

DATE-OBS= ‘2023-05-22T04:35:45.0000000’ / UTC observation date

When I use my DSLR, the values are fully populated:

DATE-OBS= ‘2023-03-03T03:02:19.3345300’ / UTC observation date

Why is this?


It’s because SGPro allows for cameras to optionally provide their own (presumably more accurate) start time. In this case it seems to be less accurate, but, because the QHY camera provides it, SGPro uses it. In the case of the DSLR, it is not provided and SGPro makes a best guess.