PC clock correction in FITS files

[Tom Alderweireldt]

Hi all,

Is it possible with ASTAP batch processing to make a PC clock time correction to reprocess a batch of old FITS files ?
The original observing PC clock was not updated online, but the time corrections compared to UTC from the dates of observation were logged, so the timestamps in the FITS files are slightly off and need correction.

Regards,
Tom.

[han.k]

Hi Tom,

That is not possible.

ASTAP can do the following:

1) Change the DATE-OBS of all files to the same value. (Change keyword value)
2) Change the file data to the DATE-OBS. This is for files where the header has been updated.

What your looking for is adding a fixed delta value to keyword DATE-OBS. value.

Is it not easier to load the " report" in a spreadsheet and add the value there?

In principle a new menu for shifting the DATE-OBS is easy to implement. But how often will it be used? So how severe is your problem?

Han

[han.k]

I decided to add it to the menu to change keywords. If you type the keyword DATE-OBS it will ask for a delta in hours.

I will finish it tomorrow. It requires to preserve the original date for recovery because it is a powerful and therefore dangerous command.

Han

[han.k]

This is implemented in development version 2024-2-9:

http://www.hnsky.org/astap_setup.exe

Make a backup of the files before you execute the command. See screenshot above. Type DATE-OBS, Then it will request for a timeshift in hour.

There is not ctrl-z functionality.

Han

[Tom Alderweireldt]

Wow, that's fast. Thanks a lot!
You were right, it's not absolutely essential, but it will save me a lot of time.
I'll try it out.

Tom.

[han.k]

Note you can type a fraction of hours if required. So a floating point value. So a one minute shift would be 0.016667. For negative values it will go back in time. Positive forward in time.

[han.k]

To modify all files you have to select all files. By e.g. ctrl+A