Comet C/2021 A1 (Leonard) (Niall MacNeill)

Celestial hemisphere: Southern · Constellation: Sagittarius (Sgr) · Contains: Solar system body or event

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Comet C/2021 A1 (Leonard)

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Comet C/2021 A1 (Leonard)

Comet C/2021 A1 Leonard is now gracing our southern skies and rapidly increasing in altitude in the evening skies. I captured this image on December 20th, when it was still quite low. I had to take this opportunity as we are now heading into at least 10 days of cloud and rain here.
There are significantly better images of this comet, but i am well pleased to have this memento. This is no doubt my best comet image as there has been something of a paucity of decent comets for southern hemisphere imagers in recent years.

I used my C11 Edge HD with the Hyperstar and the ZWO ASI 1600MC OSC camera. It was of course, quite difficult with the comet being low to the horizon in the evening sky.

This image is probably 1.5 degrees x 1.3 degrees after cropping. I used shorter exposures so the head of the comet is not blown out as much, but equally I didn’t get as much detail in the tail. In fact I took 100 x 5 sec subs and 100 x 1 sec and then effectively did an HDR combination, with the 1 sec combination used to reduce the over-exposure of the comet’s nucleus.

I used the comet process in PixInsght where the comet’s head is identified in the first and last image and the software then integrates the comet and the stars are effectively removed. I then used the software to subtract the comet and integrated the cometless stars. I then added the stars via a mask to the comet image. The mask was produced via the MaskGen function and some Deconvolution to blur it a bit.

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	Distinct awarded users	Total awarded images
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Deep sky
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Star trails
Northern lights
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	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
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Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

Status	Advanced success
Started	...
Astrometry.net job	5338867
PixInsight job	C9WJYLNBZAGL2K76BZ467QZZ4UIOUKFF
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	20h22m42s.27
RA (top/left)	20h22m09s.88
RA (top/right)	20h27m18s.56
RA (bottom/right)	20h23m16s.19
RA (bottom/left)	20h18m05s.69

Dec (center)	-29°44′12″.8
Dec (top/left)	-28°43′38″.8
Dec (top/right)	-29°54′53″.7
Dec (bottom/right)	-30°44′36″.3
Dec (bottom/left)	-29°33′00″.2

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Comet C/2021 A1 (Leonard)

Comet C/2021 A1 (Leonard)

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Comet C/2021 A1 (Leonard)

Comet C/2021 A1 (Leonard)

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