Trouble getting a value of a keyword in a FITS file.

I have a FITS file named sun.fits. With fitsinfo('sun.fits'), the structure in the image below is output.

The Image header at the end contains the structure seen in the image below.

There is a specific keyword, 'EXPTIME', in the Keywords header at the end that contains a value that I want, as seen in the third image below.

fitsread('sun.fits', image) just images the data encoded in the DataType of the second image. I tried to find a way to access that specific keyword that I need in a script but couldn't find any. Of course, I can just double click on the Keywords and just find and see the value from there but I want to write code that returns it when I know the keyword that I'm looking for.

Thanks in advance, Chris

Answer 1

[Walter Roberson]

info = fitsinfo('sun.fits');
keywords = info.Keywords;
[tf, idx] = ismember('EXPTIME', keywords(:,1));
if tf
  exposure_time = keywords{idx,2};
else
  tf = nan;
end

[Chris Anast]

At first, this was giving a 'Reference to non-existing field' error. However that is because the second line should have been:

keywords = info.Image.Keywords;

for my case. Thank you very much, sir!

Regards, Kristian