The Helix nebula (NGC 7293) is a planetary nebula located 650 light years away in the constellation of Aquarius.  The white dwarf at the center of the nebula was once a star much like our sun and when it ”died”, it blew out it’s outer gaseous layers that now form the nebula. The white dwarf is said to be about the size of our earth but has a mass very close to that of the original star.

I first photographed the Helix nebula back in August 2020 with my 10” Meade and the ASI1600mmpro. I imaged it again in Sept 2021 with the Skywatcher Esprit 120 and the ASI2600mmPro. I decided to have another go this year with the 10” Meade again but this time paired with the ASI2600mmpro and the 3nm Antlia filters. Unfortunately the weather here has been horrible with very little imaging time so was only able to capture 9hrs of Ha and 2hrs 50mins OIII.

I decided to try combining the data from all three years to see what kind of result I would get, despite the vastly different focal lengths of the 10”SCT and Skywatcher.  My main task this time was to try and show the cometary knots in a bit more detail than in my previous images. I  understand that the cometary knots were first discovered in the Helix nebula and then subsequently found in other planetary nebulae such as the Ring Nebula. Each knot is said to be roughly the size of the solar system, with tails radiating away from the central star.
One article describes them as “photoionized surfaces on the central star facing sides of neutral clouds. Material streams backwards from the rims of the ionized surfaces, producing tails”

I was surprised at how well AstroPixel Processor stacked all the calibrated subs from the two telescopes and two cameras with minimal artefacts. I tried stacking just the most recent images using the Meade 10” from this year alone, then combined with the 2020 images (again using the Meade) and finally all three years (which included the Skywatcher images) and felt that I got the best overall result using all three years combined. I then heavily cropped the image as I was wanting to show the cometary knots a bit more clearly.

The final image is therefore a combination of 4min, 5min, 10min and 15min exposures totaling 42hrs 20mins