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Supernova remnant CTA 1 - second attempt


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CTA 1 is a rarely imaged supernova remnant (aka SNR G119.5+10.2) in Cepheus, consisting of a 1.5 degree filamentary shell, so quite large.  However, it is extremely faint and my first attempt to image it during a moonlit night using NBZ dual-band filter was not very successful., although the result was interesting enough to merit a second attempt when the moon was gone. So this is the second attempt.

The bright object near the center is NGC 40, a small planetary nebula. However, they are not interacting but only happen to be on the same line of sight. The distance to CTA 1 is estimated about 4600 light years and its age is about 10’000 years. NGC 40 is about 3500 light years away from us and 4,500 years old.
CTA 1 occur in the first list of radio sources published by the CalTech Observatory in 1960, hence the annotation CTA.

Imaged on the night 26-27 Dec with a RASA8 and ASI2600MC with IDAS NBZ (Ha+Oiii) filter on a Mesu 200 mount. 62 x 5 min, so about 5 hours. Processed in PS and PI. Processing was a challenge and I had to work on a starless version (Star Xterminator) to bring out as much of the faint nebulosity as possible.

Cheers & CS, Göran

Here is a link to my first attempt a week earlier:


20211226 NGC40 RASA2 PS30smallSign.jpg

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25 minutes ago, MartinB said:

Stunning image Goran.  A dramatic improvement on the already excellent first image.  

Thanks a lot Martin for the kind words and for moving this post to the right Forum!

CS, Göran

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