Former astronomer here! You can download a lot of data from open access websites such as data.nasa.gov or any of the big digital surveys.
I don’t know about today’s data format, but it used to be all on the FITS format, with lots of libraries in Python/Matlab/etc., and also the excellent SAOImage DS9, all available for free.
Here are some links:
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SAOImage DS9: https://sites.google.com/cfa.harvard.edu/saoimageds9/download
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Space Telescope Science Institute, managing Hubble and JWST data: https://www.stsci.edu/scientific-community/stsci-library-and-institutional-archive/our-collections
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Sloan digital sky survey also has a lot of open data: https://www.sdss.org/dr19/data_access/


Its pronounced “I-see-pee”
Yes, I’m an official adult, why do you ask?