
COMET C/2022 E3 (ZTF)
🔭
Askar 130PHQ
📷
ZWO 2600MC Pro
🌃
Bortle 8
⏱️
52.5 minutes
🗓️
January 2023
Overview
Comet C/2022 E3 (ZTF), often nicknamed the green comet, made a rare close pass of Earth in early 2023. Its closest approach occurred on 1 February 2023, just two nights after this image was captured. Despite the comet’s visible coma spanning vast distances in space, the solid nucleus at its core is thought to be only around one kilometre across, a reminder of how small these icy visitors really are.
Background
I wasn’t sure I’d be able to image this comet as the weather has been so bad lately. There was a brief gap in the clouds though, so I gave it a go.
Framing it was tricky. My ASIAIR Plus did a good job of plate-solving, and got the comet within the field of view of my ZWO ASI 2600MC Pro camera, despite the relatively tight 1000mm focal length of my Askar 130PHQ telescope. I tried taking a 2-minute subframe, as is standard for me, but the comet appeared as a streak; evidently it was moving fast in the sky! I adjusted to 30-second subframes instead. I took a few and tried to work out which way the comet was moving in the sky, then moved the mount a little in that direction so that the comet would move into the centre of the frame, rather than out of it. Turns out that didn’t matter too much in the end as the cloud returned about an hour later. I also didn’t take the full size of the tail into account (to be fair, it wasn’t visible at all in the single subframes), so in the end I had to crop in quite a bit and I’d cut the tail quite short.
But still, I imaged the comet from a city centre during a gap in seemingly never-ending clouds! I’ll take that as a win.
Here’s the comet’s path over the hour:

Kit list
This is the equipment I used to capture the image.
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Telescope: Askar 130PHQ
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Camera: ZWO ASI 2600MC Pro
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Mount: Sky-Watcher EQ6-R Pro
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Guidescope: William Optics 50mm with ROTO Lock
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Guidecam: ZWO ASI 120MM Mini
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Control: ASIAIR Plus
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Processing
Processing was tough. I followed this guide from the YouTube channel View into Space.
Example source data
Here’s an example single subframe.

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