Comet 21P/Giacobini-Zinner (lowenthalm)

Celestial hemisphere: Northern · Constellation: Auriga (Aur)

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Comet 21P/Giacobini-Zinner

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Comet 21P/Giacobini-Zinner

Here is comet Giacobini-Zinner a week before it passed through M35 when it was still in the constellation Auriga. I like this image a lot, despite some odd banding which I suspect may have been caused by noisy AC power. It was almost my last target for the night - I took this at about 3:45am.

I believe the intense blue glow in the coma surrounding the comet's head is probably from singly ionized carbon monoxide that has evaporated from the surface of the comet due to heating from the sun and then ionized by UV light from the sun. You can see a slight extension of the blue coma to the upper left as it streams away becoming the comet's plasma tail. The region around the nucleus' shape is somewhat distorted by one wide jet coming from the nucleus pointing forward and a narrower jet of gas and just being emitted in the direction of the tail. These jets are a little more obvious when I don't stretch the contrast to best show the coma. The true nucleus of the comet is much too small to see inside the bright cloud of dust and gas that surrounds it that we can see at the center of the image. The prominent yellow-white tail is the dust tail, and is mostly dust, reflecting sunlight, whereas the coma produces light directly by the carbon monoxide ions emitting blue light whenever they recombine with electrons. After recombination, the molecules can again be ionized by the Sun's UV light and the process can repeat. Its bit like the inside of a neon tube, but on a cosmic scale, but instead of being powered by electricity, its powered by UV light!

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Status	Advanced success
Started	...
Astrometry.net job	2262252
PixInsight job	EXOPKVE6C1OAEDNX3DH1206CQETNF8XM
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	05h41m22s.721
RA (top/left)	05h40m55s.695
RA (top/right)	05h40m01s.343
RA (bottom/right)	05h41m49s.481
RA (bottom/left)	05h42m44s.404

Dec (center)	+36°16′18″.50
Dec (top/left)	+36°36′02″.86
Dec (top/right)	+36°04′03″.20
Dec (bottom/right)	+35°56′33″.14
Dec (bottom/left)	+36°28′29″.82

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Comet 21P/Giacobini-Zinner

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