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. The second attempt was more promising but then I could only use the subs from one of the RASAs in the double rig, since the stars were poor due to tilt in the other. However, now when I have StarXTerminator in my toolbox I could use all the 124 subs and get much deeper.
And out came this blue dragon! (at least that is what I see
), and after I lifted the Ha signal a bit in version B it became The Burning Blue Dragon.
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 occurs in the first list of radio sources published by the CalTech Observatory in 1960, hence the annotation CTA.
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