Mid-spring this year, I had the opportunity to image in Prescott,AZ with a couple nights of fantastic skies. I decided to revisit Bode's Galaxy (M81), which sits not too far from Polaris (the north star) in the night sky. This most recent image is the first shown on this page. The second image is from 2022 taken from a telescope with a much wider field of view (FoV). A little bit about this gem of a galaxy before discussing the imaging journey and then tech specs.
Bode's Galaxy (discovered by....you guessed it, a guy with last name Bode) is about 12 million light years away - or almost 5X as far away as Andromeda (M31), the galaxy in my last blog post. It's about 100k light years across (about 2/3 the size of Andromeda). One amazing fact is that it has a supermassive black hole at the center of it with a mass of ~70,000,000X that of our sun. The one at the center of the Milky Way (our own galactic home) is only ~4,000,000, despite our galaxy being larger than Bode!
The first image is taken with an Antila Tri-Band filter which has major bandpasses in each of R, G, and B, and clearly the H-alpha came out well in this image (the red splotches visible in the arm structures). These are likely regions of significant star formation. I was really happy how this image turned out.
The second image is broadband (no filter) and includes the galactic neighbor to M81 in the bottom left....unsurprisingly catalogues as M82 (aka "The Cigar Galaxy"). M82 is a starburst galaxy, which means it is undergoing an extremely high rate of star formation. It has a 3rd Galaxy in the image as well (only named NGC3077) - this is the fuzzball just up and to the left of the BortleX logo. The image was taken on an older mount of mine (an AVX) in sub-freezing conditions so cold in Prescott that the hand controller for the telescope was shutting down, and the laptop battery could not get warm enough to charge. So I had to try and put warming items under them so they could even get to operating temperature and begin self heating. My guiding was atrocious that night (fortunately not too visible unless inspecting the image up close). I may go back and attempt to process this again sometime soon, after 3 more years of post-processing learning under my belt.
So tech specs. First image was taken with 8" aperture 1280mm focal length SCT telescope using auto-guiding with an Off-axis guider. It consists of 336 images of 120 second exposures (just over 11 hours total imaging).
The second image was taken with 73mm aperture 430mm focal length Apochromatic Refractor telescope using auto guiding through a small secondary scope (2" aperture, 190mm focal length) attached to the first. It consists of just 37 images of 180 second exposure (not even 2 hours of exposure). They were post processed, stacked, stars removed using neural network based star removal software, processed separately, recombined with the stars and fine tuned in Photoshop.