Telescope: Astro-Tech 8” f/8 Ritchey-Chretien, Orion Atlas EQ-G
Camera: Canon EOS Ra, Baader Mk III MPCC
Filter: Orion Imaging Skyglow Filter
Guide scope: Astro-Tech 60mm, Starlight Xpress Super Star, PHD2
Exposure (6-26-2021): 27x120sec, ISO 800, saved as RAW
Exposure (7-2-2021): 28x180sec, ISO 800, saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flats: 32×1/25sec, Tee shirt flats taken at dusk
Average Light Pollution: Red zone, Bortle 8, fair transparency, haze
Lensed Sky Quality Meter: 18.1 (6-26) & 18.5 (7-2)
Stacking: Simple average to accommodate the two different exposure times
White Balance: Nebulosity Automatic
Software: Backyard EOS, Deep Sky Stacker, Nebulosity, Photoshop
M27, the Dumbbell nebula, is an expanding shell of gas that was ejected from a sun-like star as it exhausted its hydrogen fuel. Swollen into a red giant, the star shed its outer shell while its core collapsed into a white dwarf. Fierce UV radiation from the collapsed core sets the surrounds gas aglow with the blue/green light of doubly ionized oxygen. The diameter of the nebula is about 1 light-year with an estimated age of 9,800 years. Located between Sagitta and Cygnus, M27 is fairly easy to find with a small telescope. Visually, it shows two lobes connected by a neck of nebulosity, giving the nebula its characteristic dumbbell shape.
This is the second of three first-light images taken with my new Canon EOS Ra camera. The source images were taken over two evenings about a week apart: 27x120sec on 6-26 and 28x180sec on 7-2. The exposure times reflect the poor transparency on the evening of 6-26. I wasn’t sure how well the two different exposure times would combine, so I used a simple average algorithm rather than using the usual sigma clip.
M27 is currently well placed rising the northeast in the early evening and is high in the south after midnight.