Bright summer nights are still with us, affording a couple of hours of nautical darkness. Taking advantage of the one good night this week, I managed just over 2 hours integration on NGC 6946 - the ‘fireworks galaxy’ and lovely open cluster NGC 6939. 

Armed with a ‘new’ Altair GPCAM 130M guide camera (a birthday present), I managed 180s exposures with total  RMS 1.5” and in RA 0.7”. I only polar aligned using the inbuilt polarscope on the Star Adventurer, with some drift in declination, resulting in rather tight field edges. The SA 2i mount does not support DEC guiding, something I’m hoping to remedy without resorting to buying a GTI.

A warm, humid night, made focussing a bit of a challenge, and a low moon cast gradients. Nevertheless, after calibration and stacking the best frames in ASTAP, I processed in Siril, using Starnet to separate the starfield, sharpening the galaxy in Astrosharp. 

The stars are saturated with 3min exposures, a reminder to do 60s exposures and combine these. Star recomposition in Siril makes this straightforward. The original comprises 33 x 180s exposures. Rev B is the full stack (-duds) 47x180s with final star and noise reduction in Nebulosity 4. Rev C is processed in Startools. Personally I prefer the original which feels more natural, with a brighter background, as was.

NGC6946 an intermediate spiral galaxy in Cepheus, lies 18 mLY away, and is known as the ‘fireworks galaxy’ on account of the numerous nebulae and 10 supernovae that have been observed in the dense spiral arms. Longer focal lengths, and exposures, show a wealth of detail and some Ha data would really help light this up. 

One of the advantages of this guiding setup, is that I can now use my mono CCD (Meade DSI 3 pro) on this rig, giving more versatility for narrowband imaging.  I also have a small but capable planetary camera in the 130M (Aptina ARO130 CMOS).

NGC 6939 is an open cluster,  much closer at ~4000 LY and is estimated to be 1-2 billion years old.