Hi folks, I was having a go at some HA imaging of the California Nebula (NGC 1499) last night, but only managed 5 x 15 minute subs before the clouds rolled in. However, I stacked the images anyway, and noticed that slap-bang in the middle was a bright asteroid trail. Being a huge fan of asteroid tracking, it's odd that I didn't know it was there beforehand. It turns out that it's Asteroid (584) Semiramis, a 27km-wide object discovered in 1906 which is currently as bright as mag 10.8. It won't be this bright again for a few years. Atik 428ex, HA filter, 200mm f/5 Newtonian, 5 x 900s exposures, Off-axis guiding with a QHY5-ii. A bit noisy due to the lack of subs or calibration files. And here's an animation of the 5 images, warts 'n all:
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