The galaxy in Andromeda is the nearest large galaxy to the Milky Way, at about 2.5 million light years from Earth. It has the largest diameter of the galaxies in the local group, at approximately 220 000 light years and has around a trillion stars, about twice the number in the Milky Way. However, recent estimates suggest that its mass is about that of the Milky Way [1].
Under good conditions it is visible to the naked eye and was described around 964 by the Persian astronomer Abd al-Rahman al-Sufi in his Book of Fixed Stars.
William Parsons, the 3rd Earl of Rosse made probably the first drawing showing Andromeda's spiral structure, presumably from viewing it through his 72 inch (1.83 m) telescope, the Leviathan of Parsonstown, which was completed in 1845 at Birr Castle in the Irish County of Offaly. (This remained the world's largest telescope until the 2.5 m Hooker telescope was constructed in California in 1917.)
Isaac Roberts took one of the earliest photographs of the galaxy in 1888 and it is probably the most photographed galaxy (there are more than 8500 images listed on AstroBin alone).
But, all astro-photographers should have at least one image of this beautiful galaxy and this is mine for 2021, neither my first nor my last.
This was taken during our three clear(ish) nights in October (9 and 10) and November (6) 2021. There are around about 11.8 hours of data:
90x120 s Lum (bin 1x1)
30x120 s Red, Green and Blue (bin 2x2)
70x300 s Ha (bin 1x1)
[1] https://en.wikipedia.org/wiki/Andromeda_Galaxy
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