M1 - The expansion of The Crab Nebula over 18 Years
M1 - The Crab Nebula in Taurus
  • Description: The crab nebula is the visible cloud of expanding gas from a supernova witnessed by Chinese astronomers in 1054 AD. Material from that explosion is still expanding. I have aligned two of my later images spanning 18 years, 4 days. While there are some differences between the pictures (such as the number of stars) much of the detail is static. However, if you look at the outer edges of The Crab you can see some changes in the size of the nebula. The outer "tendrils" are clearly moving between between the two pictures.

    In the upper right of the picture a foreground star is also moving. This is TYC 1309-1640-1, a magnitude 11.6 star moving at 0.247 arc seconds per year or a total of 4.45 arc seconds over the duration of this image.

    I also have a black and white animation covering 35 years here but this version is more colourful. The two images here are as close as I can colour match! The same scope was used for both images and they were shot from the same location however the cameras were very different. The 2004 image was an old parallel-port SBIG ST8 which was fairly insensitive to blue, using a filter set with blue cut-off for use with telephoto lenses. The 2022 image was shot with a much more current sensor with good blue sensitivity, lower noise and a more accurate RGB filter set.

  • Image 1: SBIG ST-8
  • Scope 1: 8" f9 Vixen VISAC flat-field Cassegrain
  • Filter 1: Hutech Type II RGB filters.
  • Exposure 1: 20 minutes red and green, 44 minutes blue 2x2, 3 x 20 minutes luminance 1x1.
  • Location 1: Wilson Coulee Observatory, Ab.
  • Date 1: February 21, 2004

  • Image 2: SBIG STF-8300M
  • Scope 2: 8" f9 Vixen VISAC flat-field Cassegrain
  • Filter 2: Baader RGB
  • Exposure 2: 10 minutes x 5 binned 1x1 per colour
  • Location 2: Wilson Coulee Observatory, Ab.
  • Date 2: February 25, 2022
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