This is the first planetary nebula (PN) that I have imaged with my SBIG 16803 deep sky set up. Here we have the iconic Helix Nebula in the constellation of Aquarius. It is close to the Earth at 655 light years and thus has a large apparent diameter….25’. It is about 2.9 light years across. I have seen number of Northern Hemisphere imagers lamenting its low altitude, but that of course means the it is well placed for us in the Southern Hemisphere.
A dying intermediate mass star has shed its outer layers perhaps 10,000 years ago. From our vantage point, the shells of expanding gas give the appearance that we are looking into a helix and thus the name of the nebula. However, the real shape is that of a prolate spheroid….like a football. The red-orange colour is primarily due to Hydrogen Alpha emission, where the central blue-green is due to OIII emission.
I have captured about 2/3rds the Ha data I need and hope to get that and the OIII data over the next month or two, weather permitting.
As i again processed the nebula having removed the stars, I include the starless version as a mouse-over.
I recently moved to the use of RBI pre-flash, to remove the amp glow I have been suffering down one side of the image. For such an expensive camera I have been very disappointed with the performance of the SBIG 16803 in this regard. The good news is that the RBI pre-flash successfully removed the amp glow, but the penalty is higher dark current noise.
This article explains what is RBI and how RBI pre-flash can be used to eliminate it.
https://www.gxccd.com/art?id=418&lang=409I therefore had to work harder on noise reduction. I may have to consider going to lower peltier cooler temperatures to mitigate this issue. Unfortunately the medicine has side effects.
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