I have always struggled getting good data and then processing it to my liking when it comes to Galaxies. I am much more proficient at Nebulas and, as you can see if you go to the Gallery, the pictures of the galaxies are OK, but not great. Part of this is the focal length at which the 6-inch scope works that sometimes results in bloated stars. I have also never really been able to find the ‘sweet spot’ when it comes to the length of the subframes. For Nebula, I use 300 second subs and they work well. 300 seconds on a galaxy has never worked well for me. So, I decided to change things up a bit for my latest attempt at M31, the Andromeda Galaxy.
First, I went with 90 second subs hoping to still gather some detail and yet not “blow out” the core of the picture. I also gathered 1-hour of data using a Hydrogen Alpha filter, and then 2 hours of broadband data. I then stacked these subframes using what is called a “Drizzle” algorithm, which I will go into more detail later on. Developed by NASA for processing Hubble images, it improves the sharpness of each individual pixel.
This resulted in an initial stacked FITS image which was notably sharper, and I was able to really pull some detail out of it. The core as you can see is still blown out a bit, but the dark red dust lanes and even the light blue Oiii area are now visible. Andromeda has always been a tough target for me because of its size and brightness. On a clear night, it is the only galaxy that can be seen with the naked eye, and at almost 3 degrees in width is 6 times larger than the full moon. It appears faint to us because it is over 2.5 million light years away.
In any event, I will go into more detail on how this was processed on the Journey Page which I will be adding to the site in the near future. What do you think?