Comet 21P/Giacobini-Zinner

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rwilkinson
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Comet 21P/Giacobini-Zinner

Post by rwilkinson » Wed Aug 01, 2018 6:23 am

This comet has a “double-barrelled name”, since it was discovered by Michel Giacobini in 1900, and then its return in 1913 was spotted by Ernst Zinner. It’s also famous as the progenitor of the Draconids meteor shower each October (when the Earth passes through a trail of debris left by the comet on an earlier orbit), and was the first to be visited by a space-probe, when the International Cometary Explorer flew by it in 1985 (the year before it encountered 1P/Halley).

Although it has a relatively short orbital period of less than seven years, I’ve never seen it before. Back in June I first used an iTelescope to capture an image as it passed by the North American Nebula, and then even managed to detect it on a series of images taken through an upstairs window.
But it's now brightened up to 9th magnitude and is well-placed in our sky: high up in Cassiopeia, where I caught it last night:
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21p_31jul.png
Comet 21P on 31-Jul. 18x 90-sec with Mx716 on C8 at f/3.3.
21p_31jul.png (127.71 KiB) Viewed 2314 times

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Re: Comet 21P/Giacobini-Zinner

Post by rwilkinson » Sun Aug 05, 2018 10:36 am

Seeing how prominent this comet's coma was, I decided to get out my old Atik 16IC one-shot colour camera and have a try with that:
21p_4aug.png
Comet 21P on 4-Aug. 29x 90-sec with 16IC on C8 at f/3.3.
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Re: Comet 21P/Giacobini-Zinner

Post by rwilkinson » Fri Aug 10, 2018 6:55 am

The Open University's COAST Robotic Telescope on Tenerife has been out of action for several months for refurbishment, but came back online last week so I've been trying to catch this comet with it.
Their new camera is an FLI ProLine KAF-09000 with 9 megapixels of 12 microns, giving a plate scale of 0.65 arcsec/px.
21p_10aug.png
Comet 21P from Tenerife on 10-Aug. 3x 120-sec with C14 at f/11
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Re: Comet 21P/Giacobini-Zinner

Post by rwilkinson » Sun Oct 07, 2018 9:06 am

In late August and early September I did manage a few visual observations of this comet too.
I used my Helios 15x70 binoculars, first from the Wye Valley, and then from Bolton.
Then at the Star-camp in Norfolk in September we also saw it using my GEN1 image-intensifier, fitted with a 200mm lens.
As well as the fuzzy blob of the coma, I could definitely make out some of the tail too.

It's the 18th comet which I've managed to observe visually - either with the unaided eye or in an eyepiece.

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