Tuesday, 12 August 2014

Object of the Month - Veil Nebula

The Veil Nebula is not an object that has traditionally been popular with the users of the BRT. I can only assume that this is because it's not very well known. With the right settings this object can produce quite nice images.


The Veil Nebula is essentially the shock-wave from a supernova that occurred around 6,500 years ago. The light from that supernova reached the Earth around 5,000 years ago after travelling 1,500 light years to get here. As the shock-wave moves through space, it interacts with what few atoms there are in the expanses between the stars and it glows. The red is the image above is glowing Hydrogen gas and the blue is Oxygen gas.

The shock-wave now being so spread out, and with the very few potential atomic interactions in interstellar space, this object has a very low surface brightness indeed. That said, it is quite extensive. The image above just shows one section of the shock-wave (NGC 6992). The total diameter in the sky is about 6 times the size of the full moon.

You might think that this would make it an ideal target for Cluster Camera but unfortunately not. The key to getting good images of such a faint emission nebula is to use the narrowband filters. This cuts down the background sky glow and light from nearby stars that would otherwise swamp the faint clouds. At present there are no narrowband filters on Cluster Camera. It's not impossible to see the nebula but it's certainly not as clear.

Using Galaxy Cam as well as the H-alpha and OIII filters we can zoom in on individual sections of the nebula, which are covered by a number of different NGC numbers. These are shown on a map here but for reference:
  • NGC 6960
  • NGC 6974
  • NGC 6979
  • NGC 6992
  • NGC 6995
  • IC 1340
Using the maximum exposure with narrowband filters is recommended, and stacking multiple images can give improved results if you know how to do that.