Bode’s Galaxy and The Cigar Galaxy

2021-04-10 Bodes Galaxy

Bode’s Galaxy and the Cigar Galaxy are part of a galaxy cluster located about 12 million light years away in the constellation of Ursa Major – the constellation that includes the Plough.  The galaxies were first observed by German astronomer Johann Bode in 1774 and included in Messier’s catalogue as M81 and M82 in 1779.  Bode’s galaxy (M81) is about 90,000 light years across, making it about half the size of our own Milky Way. Nevertheless, its relative closeness makes it one of the larger galaxies in our night skies, and it is nicely angled to show off its spiral structure, making it a good target for amateur astro-photography.  M82 is a little smaller than M81 and is located about 120,000 light years from it. The relative closeness of the galaxies has created a lot of gravitational interactions, which has resulted in massive bursts of star formation in M82 – in fact, it is the prototype galaxy for a type known as a Starburst Galaxy. Due to these interactions, star formation in the core of M81 is about 10 times as energetic as our entire (much larger) Milky Way galaxy. This massive burst of new star formation also results in a large number of supernova, and the resulting radiation winds from new stars and supernova have blasted clouds of hydrogen gas out of the core – these filaments can just be seen as dark lines in the image above.   

To achieve a close-up image of theese galaxies, the image above was taken with a Skywatcher 200P telescope – an 8 inch aperture Newtonian reflector with a 1000mm focal length. Most advice is that this scope is too large for astro-photography on my HEQ5 mount. However on a still night with no wind and with good guiding calibration, the tracking accuracy is quite acceptable, as can be seen from the details visible in M81 and M82.  One problem which this image does however highlight is the effect of coma, which is a distortion that arises with reflecting telescope. This has the effect of elongating the stars towards the edges of the image.  This can be corrected by a Coma Corrector – another piece of kit to add to the list of things to buy!   

Image Details

  • Date: 9th April 2021
  • Exposure Details: 43 x 300s, F5, ISO400
  • Total Integration Time: 3hr 35min
  • Camera: Canon EOS80D (unmodified)
  • Telescope: Skywatcher 200P at 1000mm
  • Mount: Skywatcher HEQ5
  • Guide Scope: Altair Astro 60mm Guidescope
  • Guide Camera: QHY5LII
  • Filters: Skywatcher Light Pollution Filter

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