Data for this image is from my last effort to create a mosaic of the Cygnus Loop. I don’t remember exactly how many nights were involved. A quick check shows it happened between 2020/06/06 and 2020/09/27. The backyard imaging for this project was finished before I switching gears to prepare the remote observatory team installation.

Data Details (2-Panel Mosaic):

Ha – 336 x 2, 300s, Gain 100
S-II – 336 x 2, 300s, Gain 100
O-III – 336 x 2, 300s, Gain 100

After letting the data sitting on the disk for 4 months, I decided to put the data together and make an image. The first thing I noticed is that the light pollution is getting much worse in my area year by year. One example – I even got a strong gradient with the Ha 3nm filter. There are strong gradient bars in the middle of the S-II and O-III mosaic masters. Even with 168 hours, the SNRs are so poor. Hats off to all backyarders!

This is a typical HSO narrowband blend. A portion of Ha and O-III joined S-II to form the green channel. Synthetical luminance was created with all three mosaic masters by lighten blending with SHO-AIP script. Multiple hue selections done to separate the colors.

This image was picked as the Astrobin image of the day (IOTD) on 02/10/2021.

This image won Highly Commended in the Astrophotographer of the Year 2021, Stars and Nebula category on 09/16/2021.

“This is an image that every astronomer and astrophotographer wants to see at least once in their lifetime: the entire, pure Cygnus supernova remnant, cleared from every disturbing element. As a result, this calm, emblematic bubble structure emerges from the dark, with uncountable details. This astro-image is a unique photograph.

 László Francsics, competition judge”