Sharpless 183 (2025) |
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 Sharpless 183 - Click on thumbnails below to view larger image. Opens in a new window. |
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This image is another "happy accident" of my 2025 data.
I selected this narrowband target to image, completely
forgetting until I was a few nights in that I had already imaged
it back in 2012. I figured since I had started imaging this, I might as well continue.
And recalling that it was very faint, I decided to go a bit
deeper than my prior attempt. This group of emission nebulae (SH2-183 is the larger emission nebula, SH2-181 is the "horn") has been nicknamed by some as "The Demon", but my personal sense of pareidolia sees the logo of the NBA team the Chicago Bulls, especially at this orientation. See my caption from 2012 for details. Sharpless 183 and the accompanying Sharpless 181 (the bull's single horn) are dim diffuse nebulae in the constellation Cassiopeia. There is little information about this object, but according to galaxymap.org, they are mostly obscured by foreground dust, it contains about of 44 thousand solar masses of gas and are at least 3.9 million years old. It is unknown which stars are ionising the gas (making it glow), which are probably obscured by the foreground dust. The obscuring dust could explain at least part of these targets' faintness. Other interesting facts is that the estimated distances of the SH2-181 and SH2-183 place them thousands of light-years away from each other, so they just happen to line up in our field of view. |
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| Constellation: Cassiopeia | ||
| When Visible: October - March | ||
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Distance: SH2-181: from 6,500 to 8,000 light-years (estimated).
SH2-183: over 22,000 light-years (estimated) |
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| Date Imaged: November 3-10, 2025 | ||
| Location: Starfront Observatories, Rockwood, TX | ||
| Exposure Details:
Ha: 111 x 10 Minutes Binned 1x1 SII: 121 x 10 Minutes Binned 1x1 OIII: 68 x 10 Minutes Binned 1x1 R: 24 x 3 Minutes Binned 1x1 G: 27 x 3 Minutes Binned 1x1 B: 30 x 3 Minutes Binned 1x1 Fifty-four hours and 3 minutes total exposure time |
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| Equipment Used: Takahashi FSQ-106N on a ZWO AM5N mount. ZWO ASI-2600MM Pro camera with 7 x 50mm filter wheel and Antlia Pro filters. Externally guided with a ZWO ASI224MC camera on a William Optics UniGuide 50 guide scope. | ||
| Acquisition Software : Nighttime Imaging 'N' Astronomy, PHD2 | ||
| Processing Software: PixInsight, Photoshop CS5, IrFanView | ||
