M51 images
The actual HST images can be obtained from
https://archive.stsci.edu/prepds/m51/datalist.html
The images I used in the scripts, which are around 26mb each:
h_m51_i_s20_drz_sci.fits h_m51_b_s20_drz_sci.fits h_m51_h_s20_drz_sci.fits h_m51_v_s20_drz_sci.fits