01
Sep
2021
This was definitely my biggest project so far. 32h (!) of total exposure time, taken over the course of 12 nights.
Now that my O-III filter has finally arrived, I wanted to some narrowband imaging of this iconic nebula. Due to my rather long focal length of 1125mm, I decided to go for a 2x2 mosaic, showing the (faint) surrounding Ha nebulosity
For each panel the exposure time sums up to 8hrs. 4hrs for Ha and 4hrs for O-III.
The resulting dataset was around 15GB of photos!
Go ahead and check the finished photo at the bottom of this page and notice how far you can zoom in. The 4x4 mosaic yielded a ~80MP photo, and with drizzle integration (in PixInsight) the resolution got bumped up even further to 240MP.
The Crescent Nebula
The crescent nebula got it’s form through interstellar winds. These interstellar winds are made up of strong magnetic fields, which originate from rare Wolf-Rayet type stars. These magnetic winds then accelerate or “push” ionised gases like hydrogen and oxygen.
Because of the narrowband filters, certain colors show different chemical elements. In the case of this photo, red shows hydrogen and blue shows oxygen.
The Soap Nebula
While processing all the data, I noticed a bubble like shape on the edge of my photo, only appearing in the O-III (oxygen) data. At first I thought that it probably is some weird optical artifact (like a reflection or a dust particle on the filter or camera sensor or similar). However, after some further research I actually found out that this is a known nebula called The Soap Nebula, which was only recently discovered in 2008 by another amateur astronomer.
It can be seen in my photo at the very outer left edge, somewhere towards the bottom of the image:
The Soap Nebula is a planetary nebula, meaning an old star that died and shed away its outer layers of gases, leaving behind only a white dwarf.