The Dumbbell Nebula (also known as the Apple Core Nebula, Messier 27, and NGC 6853) is a planetary nebula (nebulosity surrounding a white dwarf) in the constellation Vulpecula (Little fox in Latin), at a distance of about 1360 light-years from Earth. It was the first such nebula to be discovered, by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and diameter of about 8 arc minutes, it is easily visible in binoculars and is a popular observing target in amateur telescopes. (Source: Wikipedia)
I acquired the data for this image from my backyard in San Jose, CA (Bortle 8) over 9 nights, from June 2nd, 2021 to June 11th, 2021, adding up to 34 hours of data. Unfortunately, the first night was a complete loss because I somehow had the wrong filter selected as part of my sequence... As many as half of the remaining subs were rejected because of wind gusts and various guiding issues. In spite of the high level of rejection, a lot of the approved frames still had slightly elongated stars. While I tamed those eggy stars as much as I could in post-processing, it still shows up in the final image, unfortunately. So, there is room for improvement in the acquisition phase.
I noticed that I had a little bit of flexure in my system. However, that is not the cause of the elongated stars. See this thread on Cloudy Nights:
https://www.cloudynights.com/topic/775260-good-guiding-but-elongated-stars-along-e-w-direction/- Telescope: Astro-Tech AT130EDT with HoTech SCA field flattener
- Mount: iOptron CEM70
- Camera: ZWO ASI533MC Pro (OSC)
- 412 x 5 minute exposures with Optolong L-eXtreme (Ha + OIII narrowband filter)
- Processed in PixInsight
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