The Great Andromeda Galaxy is the nearest major galaxy to our own Milky Way. In this huge ~10º (20 full moons) field, the galaxy is shown in its cosmic context with its surroundings. It’s catalogued as M31 (along with its satellite M32 and M110), located 2.5 million light years away, stretching some 200.000 light years across. [1] Our Galaxy is thought to look much like Andromeda, a great spiral. Together these two galaxies dominate the Local Group of galaxies. A noteworthy fact is that the stars we see in this image, even the individual stars “in Andromeda” are not actually there – they’re Milky Way stars “in the middle of the way”, well in front of the background object. [1]

Andromeda’s discovery is very interesting. Al-Sufi, around 964, described it in his Book of Fixed Stars as a “nebulous smear”. M31 is visible to the naked eye – probably observed since ancient times. [2] M31 was catalogued in 1764 by Charles Messier – a comet hunter that listed fuzzy objects that looked like comets not to confuse them. At that time (17th century), the nature of these fuzzy objects was not known, and they were labelled Nebulas. [3] Interesting to note philosopher Immanuel Kant’s conjecture that the blurry spot was an “island universe” in 1755! The debate of the true nature of these “island universes” was finally solved around the 1920s by Edwin Hubble using Cepheid variable stars. Andromeda was proved to be outside of the Milky Way, galaxies were distant “island universes” indeed. Hubble also observed that the galaxies were moving away from us – the Universe is expanding. [2] [3]

Much more recent surveys and photographs reveal a very faint nebulosity around the entire region – Galactic Cirrus (or IFN). Some fantastic imagers have also captured insanely faint H-alpha nebulosity around Andromeda – I recommend checking out the fantastic work of Rogelio Bernal Andreo and the MDW H-alpha Survey, which show those clouds in beautiful images. [4]

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M31 is a famous object among astrophotographers. It is imaged many (perhaps too many) times…. But I needed to capture a better image of my own of this object as I was not satisfied with my previous attempts. The wide field is a somewhat different field as the usual ~600mm FL images we often see, which frame the galaxy more tightly. This image was captured in the holiday of Sept. 7-8, in a trip that rendered great images. This object is much higher in the sky from the Northern Hemisphere, but to my -22º latitude, M31 never rises more than 20 degrees above the horizon. I believe this is my best M31 to date, and I might call this object done for now – finally going for some different (fainter, less imaged) targets on the same region.

Processing was surprisingly not difficult – the raw data was very good as the night conditions were great (cloudless and clear). Some light-pollution gradient was present – but this was merely 20º high! My objective was to capture not only the galaxy but also its faint halo and hints of the IFN in the region. My 70min integration was not enough to resolve the IFN, but it can be hinted (very slightly) in the inverted overstreched version I also post [please check it as well]… The halo is also visible! I was very satisfied and happy!

Constructive criticism, comments and suggestions are more than welcome in the comments section – including on the new labelling. Thank you for taking your time to look at this image.

Date and Time: September 08, 2018; ~0h [local UTC-3 time]

Location: MG, Brazil. Rural Skies (Bortle 3-4, SQM ~21.5*calculated)

Camera: Canon EOS T5 (modded), at ISO 800

Lens: Samyang 135mm f/2.0, operated at f/2.4

Mount: Sky-Watcher HEQ5, tracking, guided

Guiding: Starguider 50mm Guidescope + ASI120mm + PHD2; ~1.3”

Exposure Detail: 35x120s. Total 70 minutes

References: [1] APOD 2017/01/04 and 2015/08/30; [2] Wikipedia; [3] Las Cumbres Observatory lco.global/spacebook/history-discovery ; [4] deepskycolors.com and mdwskysurvey.com