After several weeks of clouds and rain, I finally managed to take an image of this beautiful comet under 85% illuminated Moon. Despite the conditions, I was able to capture 7x2 minute exposures through passing thin cirrus clouds before thicker clouds fully covered the sky. Although I wished for more exposure time, the unpredictable weather did not cooperate. I'll give it another try in about a week, weather permitting, before imaging becomes even more challenging. Unfortunately, it seems we'll be stuck with this foul weather for at least another 10 days, according to the forecast. Nonetheless, I'm satisfied with the results considering the conditions and the overall exposure time. I love the comet colors, the typical green coma, the very faint reddish/brownish hue near the coma and where the tail connects, and the two-color bluish and whitish extended tail. The discontinuities and breaks along the tail are quite mesmerizing too.
Here's a breakdown of the steps I followed:
- For stars: Selected a reference frame and registered and stacked stars the normal way with DSS. Did background extraction and photometric color calibration with Siril. Stretched the image with GHST in Siril. Removed the stars and saved the star mask for later combination with the comet.
- For the comet: With the same reference frame, I aligned and registered all frames now using the comet mode in Deep Sky Stacker. Performed background extraction and photometric color calibration on all registered comet frames in Siril.
- In Siril, removed stars from background-extracted, color-calibrated comet frames in linear mode using Starnet++.
- Median-stacked all starless, background-extracted, color-calibrated comet frames with windsorized sigma clipping (sigma-low=3 and sigma-high=2) in Siril. The star residuals were minimal, and the signal in the tail remained almost intact after sigma-clipping. Stretched the image with GHST in Siril.
- Applied denoising to the stretched comet stack image using Topaz.
- Used various masks in GIMP to saturate and brighten only the comet portion of the denoised comet-stacked image.
- Combined the stars with the comet image in GIMP using layers and screen mode for the star layer.
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