[AstroPy] Seeking Assistance: Issues Updating WCS Headers

[Mohammad Shameoni Niaei]

 Dear Astropy

I hope this message finds you well. I’m reaching out for some help
regarding an issue I’ve encountered while updating WCS headers.

Here's a rundown of what I'm facing: I’ve created a new header using
fit_wcs_from_points, and when I use to_header on the result and save the
header, everything seems to function properly. However, I’m eager to
preserve other crucial values from the previous header, like airmass, among
others.

To retain these values, I attempted to update the old header with the
header from the newly generated WCS object. However, despite these efforts,
both DS9 and world_to_pixel continue displaying the old pixel-to-sky
relation.

Here's a snippet of the code I've been working with:

w = WCS(header)

highest = min(self.data().shape)
xs = np.random.randint(0, highest, 20)
ys = np.random.randint(0, highest, 20)

skys = w.pixel_to_world(xs.tolist(), ys.tolist())

new_w = fit_wcs_from_points([xs + x, ys + y], skys)

temp_header = header.copy()
temp_header.update(new_w.to_header())

# saving it....


I'm a bit perplexed as to where I might be going wrong in this process.
Could anyone with experience in handling WCS headers or a similar issue
lend some guidance or suggestions on how I might rectify this?

Thank you so much for your time and any help you can provide.

Ps: The data I work with:
https://www.astropy.org/astropy-data/tutorials/FITS-images/HorseHead.fits

Best regards,

-- 
Mohammad Shameoni Niaei
Astronomer
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