Comet Chasing in December
Comet chasing is the visual observation of telescopic comets. Jump to: Observing synopses Summary data Buy me a Coffee
This month there is one comet visible in binoculars, one visible in small telescopes, and two visible in 6-inch or larger telescopes (from a dark site). See the Observing Synopses for which comets are visible from your latitude, the best dates and the time of night.
C/2024 G3 (ATLAS) will reach perihelion on January 13 2025, when it will pass within 0.1 AU of the sun. This may be an interesting comet to follow in the coming months, as it is too soon to predict how bright it will get, and there is a strong possibility that it will disintegrate. It brightened by a magnitude at the end of October, heightening the uncertainty.
C/2023 A3 (Tsuchinshan-ATLAS) was very impressive in October. Although forgotten by the media, it remains a very nice telescopic comet throughout the month. If this was as good as it would get, we would still be highlighting it. See below for observing details, as well as the video above.
333P/LINEAR is a periodic comet that passes within 1.1 AU of the Sun every 8.7 years, most recently on November 29th. It will pass withing 0.5 AU of the Earth in early December, when it will reach maximum brightness of 11.5.
29P/Schwassmann-Wachmann has frequent outbursts, typically resulting in a brightening of 0.5 - 1.0 magnitudes, which occur roughly every 59 days, typically taking 5-10 days to subside. Up to three subsequent outbursts may occur 5-10 days afterward, each typically smaller than the last, although on some occasions they can be even brighter than the first. These outbursts make 29P one of the most interesting comets to follow, both visually and scientifically. 29P/Schwassmann-Wachmann has a 14.8-year orbital period, and last passed perihelion in early March 2019. It varies in its distance from the Sun from 5.8 AU (at perihelion) to 6.3 AU (at aphelion), which is an unusually small variation for a comet, and remains quite far from the sun at all times. This means that it can be observed more or less continuously.
C/2024 S1 (ATLAS) has disintegrated near the sun. Despite all the talk, there was little chance that this comet was ever going to be more than a SOHO comet. Beware that some software and web sites may still show it as active.
C/2022 E2 (ATLAS) is past perihelion, which occurred in mid September 2024. It is predicted to reach maximum brightness of magnitude 12.8 in early December.
C/2023 C2 (ATLAS) will reach perihelion in mid November. It was at maximum brightness in October.
Comet 13P/Olbers passed perihelion in late June and is fading.
Comet 12P/Pons-Brooks passed perihelion on April 21 and has become a southern-hemisphere object. It is fading.This well-documented comet, perhaps observed as early as the year 245, experienced a large unexpected outburst in late July 2023, catapulting from a magnitude of 16.6 to 11.6 in a single day. Afterward it displayed an unusual coma shape, characterized by a distinctive 'notch' and a pair of 'horns' that persisted for weeks. The same pattern repeated in the following months, except in recent outbursts the 'horns' have become longer and curved. Here is a link to a video with an animation of the July outburst aftermath C/2021 S3 (PANSTARRS) passed perihelion in mid February 2024.
C/2014 UN271 (Bernardinelli-Bernstein) is an interesting Oort cloud comet that was reported as a result of the Dark Energy Survey. Soon after it was made public, images showed a cometary coma. Discovery credit goes to Pedro Bernardinelli and Gary Bernstein. This is a remarkable comet that was at 29 AU in 2014, with a perihelion of 10.9 AU in 2031. Its orbit extends out to 40,000 AU! It was unusually bright for its distance. HST
Comets that have apparently di
sintegrated: C/2024 S1 (ATLAS), C/2022 S3 (PANSTARRS), C/2021 P4 (ATLAS), C/2020 Q1 (Borisov), C/2020 P1 (NEOWISE), and C/2019 Y4 (ATLAS). Beware that various other sources often fail to keep track of whether or not a comet still exists!Comet Visibility in the Eyepiece
When you read below that a particular aperture is required to see a comet you can have a reasonable degree of confidence that the comet can in fact be seen in the eyepiece.
This
page uses code developed for SkyTools to predict the visibility of a comet. Predicting how much
aperture is required to see a comet is a very complex task. The magnitude
alone is a very poor predictor. SkyTools considers the magnitude, coma
diameter, degree of concentration of the comet, based on recent
observations.The predictions are made for a Country/Suburban site,
which is approximately
Bortle
5, unless
indicated otherwise. But always
remember, comets are like cats. They both have tails and do what they want, and
not always what we expect. This is one of the things that makes comet chasing
interesting!
Observing
Synopses for December
Explanation
of Comet Synopses and charts (read this if you have questions) C/2024 G3 (ATLAS): A
southern hemisphere morning comet visible in binoculars C/2023 A3
(Tsuchinshan-ATLAS): An evening comet visible in small telescopes 333P/LINEAR: A northern
hemisphere morning comet visible in a 6-inch (15 cm) telescope at a dark site,
or a 18-inch (46 cm) under a country sky 29P/Schwassmann-Wachmann:
A morning comet visible in a 6-inch (15 cm) telescope at a dark site, or an
8-inch (20 cm) under a country sky C/2022 E2 (ATLAS): A
northern hemisphere evening comet visible in an 8-inch (20 cm) telescope at a
dark site, or a 24-inch telescope under a country sky C/2024 M1 (ATLAS): A
morning comet visible in a 16-inch (41 cm) telescope at a dark site C/2023 C2 (ATLAS): An
evening comet visible in a 24-inch telescope at a dark site Summary
Data for This Month's Telescopic Comets
This comet begins the month in Lupus at magnitude 10.1. Look for
a 1' coma, condensation is a diffuse spot in coma center; moderately condensed.
It should brighten rapidly, moving into Scorpius by month's end. The best
visibility is late in the month as seen from the southern hemisphere. FINDER
CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
Not visible
Not visible
Not visible
Not visible
Not visible
40o
N
Not visible
Not visible
Not visible
Not visible
Not visible
Equator
Not visible
Not visible
Not visible
Not visible
Very low in the eastern sky
during morning twilight at ~05:20
17-
30o S
Not visible
Not visible
Not visible
Very low in the eastern sky
during morning twilight at ~04:00
Very low in the eastern sky
during morning twilight at ~04:10
1-
This comet begins the month in Aquila at magnitude 9.1. Look for
a 2.5' coma, condensation is a diffuse spot in coma center; moderately
condensed. It should fade by about 1.4 magnitudes by month's end. FINDER
CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
Fairly high in the western sky
during evening twilight at ~17:30
Fairly high in the western sky
during evening twilight at ~17:30
Fairly high in the western sky
during evening twilight at ~17:30
Fairly high in the western sky
during evening twilight at ~17:30
Low in the western sky during
evening twilight at ~17:30
1-
40o
N
Fairly high during evening
twilight at ~18:00
Fairly high in the western sky
during evening twilight at ~18:00
Fairly high in the western sky
during evening twilight at ~18:00
Fairly high in the western sky
during evening twilight at ~18:00
Low in the western sky during
evening twilight at ~18:00
1-
Equator
Fairly high in the western sky
during evening twilight at ~18:50
Low in the western sky during
evening twilight at ~19:00
Low in the western sky during
evening twilight at ~19:00
Not visible
Not visible
1-23
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
1-2
This comet begins the month in Canes Venatici at magnitude 11.6.
Look for a 2.5' coma, center much brighter than edges, though still diffuse. It
should fade by about 1.2 magnitudes, moving into Cygnus by month's end. FINDER
CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
High during morning twilight at
~05:50
High during morning twilight at
~06:00
High during morning twilight at
~06:20
High during evening twilight at
~17:50
High during evening twilight at
~17:50
1-
40o
N
High during morning twilight at
~05:30
High during morning twilight at
~05:40
Fairly high during morning
twilight at ~05:50
High during evening twilight at
~18:10
High during evening twilight at
~18:20
1-
Equator
Fairly high during morning
twilight at ~04:40
Not visible
Not visible
Not visible
Not visible
1-7
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
This comet begins the month in Leo at magnitude 12.1. Look for a
1.5' coma, condensation is a diffuse spot in coma center; moderately condensed.
It should brighten slowly overall, but will likely fade after the recent
outburst. FINDER CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
High at ~05:30
High at ~05:00
High during morning twilight at
~06:10
High in moonlight at ~04:00
High at ~03:40
1-
40o
N
High during morning twilight at
~05:30
High at ~05:00
High during morning twilight at
~05:50
High in moonlight at ~04:10
High at ~03:40
1-
Equator
High during morning twilight at
~04:30
High at ~04:30
High during morning twilight at
~04:50
High in moonlight at ~04:10
High at ~03:40
1-
30o S
High during morning twilight at
~03:30
High during morning twilight at
~03:20
High during morning twilight at
~03:40
High during morning twilight at
~03:20
High during morning twilight at
~03:30
1-
This comet begins the month in Camelopardalis at magnitude 12.8.
Look for a 1' coma, center much brighter than edges, though still diffuse. It
should fade slowly, moving into Cassiopeia by month's end. FINDER
CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
High at ~00:10
High at ~23:00
Not visible
High at ~20:50
High at ~20:00
1-
40o
N
High at ~00:10
High at ~23:00
Not visible
High at ~20:50
High at ~20:00
1-
Equator
Not visible
Not visible
Not visible
Fairly high in the northern sky
at ~20:50
Fairly high in the northern sky
at ~20:00
1-
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
This comet begins the month in Orion at magnitude 14.8. Look for
a 35" coma, condensation is like a star that cannot be focused; strongly
condensed. It should fade by about 0.7 magnitudes, moving into Perseus by
month's end. FINDER CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
High at ~00:50
High at ~23:50
Not visible
High at ~21:50
High at ~20:50
1-12, 15-
40o
N
High at ~00:50
High at ~23:50
Not visible
High at ~21:50
High at ~20:50
1-12, 15-
Equator
High at ~00:50
High at ~23:50
Not visible
High at ~21:50
High at ~20:50
1-
30o S
High at ~00:50
High at ~23:50
Not visible
Fairly high in the northern sky
at ~21:50
Fairly high in the northern sky
at ~20:50
1-
This comet begins the month in Sagittarius at magnitude 13.8.
Look for a 30" coma, diffuse condensation at center. It should fade slowly,
moving into Capricornus by month's end. FINDER
CHART
Latitude
Visibility November 30
Visibility December 7
Visibility December 14
Visibility December 21
Visibility December 28
Nights Visible
55o
N
Not visible
Not visible
Not visible
Not visible
Not visible
40o
N
Low in the western sky during
evening twilight at ~17:50
Not visible
Not visible
Not visible
Not visible
1-6
Equator
Fairly high in the western sky
during evening twilight at ~19:00
Low in the western sky during
evening twilight at ~19:00
Not visible
Not visible
Not visible
1-13, 15-16
30o S
Low in the western sky during
evening twilight at ~20:00
Not visible
Not visible
Not visible
Not visible
1-5
Comets
brighter than 16th magnitude. This table is
updated as necessary. The last column indicates the date of the last
observation used to compute these values. The constellation listed is
where the comet was on the first of the month.
| Comet | Constellation |
December 1st |
December 15th |
December 31st |
Observations as of (UT) | |||
| Mag | Diam | Mag | Diam | Mag | Diam | |||
| C/2023 A3 (Tsuchinshan-ATLAS) | Aquila | 9.1 | 2.3' | 9.9 | 2.0' | 10.6 | 1.7' | 2024 December 1 |
| C/2024 G3 (ATLAS) | Lupus | 10.1 | 45" | 8.6 | 53" | 5.5 | 1.2' | 2024 November 28 |
| 13P/Olbers | Ophiuchus | 10.9 | 2.7' | 11.3 | 2.6' | 11.6 | 2.5' | 2024 October 20 |
| 333P/LINEAR | Canes Venatici | 11.6 | 2.2' | 11.6 | 2.4' | 12.8 | 1.5' | 2024 December 1 |
| 29P/Schwassmann-Wachmann | Leo | 12.1 | 1.5' | 12.0 | 1.6' | 11.9 | 1.6' | 2024 December 1 |
| C/2022 E2 (ATLAS) | Camelopardalis | 12.8 | 1.1' | 12.9 | 1.1' | 13.0 | 1.0' | 2024 October 29 |
| 12P/Pons-Brooks | Lupus | 13.3? | 4.2'? | 13.6? | 4.1'? | 13.8? | 4.0'? | 2024 September 30 |
| C/2024 B1 (Lemmon) | Corona Borealis | 13.8 | 1.1' | 14.1 | 1.1' | 14.4 | 1.0' | 2024 November 1 |
| C/2023 C2 (ATLAS) | Sagittarius | 13.8? | 32"? | 13.9? | 30"? | 14.0? | 29"? | 2024 September 5 |
| 37P/Forbes | Sagittarius | 14.1 | 48" | 14.5 | 46" | 15.1 | 43" | 2024 November 28 |
| C/2021 G2 (Atlas) | Libra | 14.5? | 47"? | 14.4? | 48"? | 14.4? | 49"? | 2024 August 29 |
| C/2024 M1 (ATLAS) | Orion | 14.8 | 37" | 14.9 | 36" | 15.5 | 29" | 2024 November 30 |
| C/2022 N2 (PANSTARRS) | Aquarius | 15.0 | 36" | 15.1 | 35" | 15.1 | 33" | 2024 November 22 |
| C/2020 V2 (ZTF) | Pavo | 15.2? | 52"? | 15.3? | 50"? | 15.4? | 49"? | 2024 August 30 |
| 487P/SidingSpring | Perseus | 15.3 | 29" | 15.6 | 26" | 16.0 | 23" | 2024 November 30 |
| C/2019 U5 (PANSTARRS) | Puppis | 15.5 | 48" | 15.5 | 48" | 15.6 | 47" | 2024 November 1 |
| C/2022 QE78 (ATLAS) | Monoceros | 15.6 | 33" | 15.5 | 34" | 15.4 | 34" | 2024 November 22 |
| C/2017 K2 (PANSTARRS) | Orion | 15.6 | 1.0' | 15.7 | 1.0' | 15.8 | 1.0' | 2024 September 22 |
| C/2021 S3 (PANSTARRS) | Cygnus | 15.8 | 45" | 16.1 | 43" | 16.4 | 40" | 2024 September 27 |
| 472P/NEAT-LINEAR | Monoceros | 16.0 | 42" | 16.0 | 42" | 16.0 | 42" | 2024 November 28 |
| C/2024 J2 (Wierzchos) | Hercules | 16.0 | 48" | 15.8 | 49" | 15.5 | 51" | 2024 November 4 |
| C/2023 H5 (Lemmon) | Coma Berenices | 16.2 | 44" | 16.1 | 47" | 15.9 | 49" | 2024 November 29 |
For information about specific comets see Gary W. Kronk's Cometography
Further reading: see Comet Chasing, Sky & Telescope, April 2005, pg. 83.
Make your own visual observing custom charts for your location and telescope/binoculars: Software for visual comet observing
Select comets that are appropriate for your
imaging system, and plan when they are best imaged: Software
for comet imaging
| Links
Skyhound's Guide
to Comets
|