Comet Chasing in October Comet chasing is the visual
observation of telescopic comets. Jump to: Observing
synopses Summary data
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This month is highly unusual, in that only one comet is generally observable in telescopes with apertures less than 10-inches (25 cm). But this comet is visible to the unaided eye. Only three comets are visible in 10-inch or larger instruments.
See the Observing Synopses for which comets are visible from your latitude, the best dates and the time of night.
C/2023 A3 (Tsuchinshan-ATLAS) has started to impress, at least in images. See below for observing details, as well as the video above.
C/2023 C2 (ATLAS) will reach perihelion in mid November. It is predicted to reach maximum brightness of magnitude 13 in October.
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.13P/Olbers passed perihelion in late June.
Comet 12P/Pons-Brooks passed perihelion on April 21 and has become a southern-hemisphere object. It is now fading rapidly.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 crived. 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. It is now fading slowly, but continues to display a nce tail in images.
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/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 obsrvations that isolate the nucleus estimate the diamter to be between 120 and 140 km, making this possibly the largest comet nucleus yet measured. Because of its distant perihelion, this comet is not expected to become bright enough to be visually observed except in large instruments, and not until the end of the decade, but it is likely going to be the subject of intense scientific scrutiny.
Comets that have apparently disentegrated: CC/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
This
page uses code developed for SkyTools to predict the visibility of a comet in the
eyepiece. Predicting how much
aperture is required to see a comet is a very complex task. Have a look
for yourself: a comparison of the predictions below (such as "visible in
small telescopes") to the magnitude of each comet shows just how poor an
indicator the magnitude alone really is. 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. 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!
The predictions are makde for a Country/Suburban site,
which is Bortle
5, unless
indicated otherwse. .
Observing
Synopses for October
Explanation
of Comet Synopses and charts (read this if you have questions) C/2023 A3
(Tsuchinshan-ATLAS): An evening comet visible in binoculars 13P/Olbers: An evening
comet visible in small telescopes at a dark site, or a 10-inch (25 cm) under a
country sky C/2022 E2 (ATLAS): A
northern hemisphere morning comet visible in an 8-inch (20 cm) telescope at a
dark site, or a 18-inch (46 cm) under a country sky C/2023 C2 (ATLAS): A
southern hemisphere evening comet visible in a 10-inch (25 cm) telescope at a
dark site, or a 24-inch telescope under a country sky Summary
Data for This Month's Telescopic Comets
This comet begins the month in the morning sky, brightening, but closing on the sun, moving lower and more into twilight. On October 9 it will be at its brightest, but will be too close to the sun to be visible. After that it will move into the evening sky, first visible on the 11th of October, when it will be low in the sky and difficult to observe. It will fade rapidly, but also move higher into a darker sky. It terms of how large and magnificent it will be, the evenings after October 11 are preferred, but in terms of getting a good look at it, the following week will provide fine views even as it fades.
We are predicting naked eye visibility throughout this time, ranging from perceptible to easy, depending on the circumstances.
It is unlikely to be as bright as the media is going to say it is, and there is
no sign at this time that it will be the comet of the century, as has already
been widely reported in the media. It will be obvious in binoculars for most of the month. For more details and charts see the video at the top of the page.
Latitude
Visibility September 28
Visibility October 5
Visibility October 12
Visibility October 19
Visibility October 26
Nights Visible
55o
N
Not visible
Not visible
Very low 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
1-3, 11-
40o
N
Very low in the eastern sky
during morning twilight at ~05:10
Not visible
Very low in the western sky
during evening twilight at ~18:10
Fairly high in the western sky
during evening twilight at ~18:10
Fairly high during evening
twilight at ~18:20
1-5, 11-
Equator
Low in the eastern sky during
morning twilight at ~05:20
Very low in the eastern sky
during morning twilight at ~05:20
Very low in the western sky
during evening twilight at ~18:20
Fairly high in the western sky
during evening twilight at ~18:30
Fairly high during evening
twilight at ~18:50
1-5, 12-
30o S
Low in the eastern sky during
morning twilight at ~05:00
Not visible
Not visible
Low in the western sky during
evening twilight at ~19:00
Fairly high in the western sky
during evening twilight at ~19:10
1-4, 13-
This comet begins the month in Virgo at magnitude 9.3. Look for
a 3.5' coma, condensation is a diffuse spot in coma center; moderately
condensed. It should fade by about 1.2 magnitudes, moving into Libra by month's
end. FINDER CHART
Latitude
Visibility September 28
Visibility October 5
Visibility October 12
Visibility October 19
Visibility October 26
Nights Visible
55o
N
Low in the western sky during
evening twilight at ~19:10
Not visible
Not visible
Not visible
Not visible
1-20
40o
N
Low in the western sky during
evening twilight at ~19:00
Low in the western sky during
evening twilight at ~18:50
Low in the western sky during
evening twilight at ~18:30
Not visible
Not visible
1-26
Equator
Low in the western sky during
evening twilight at ~18:50
Low in the western sky during
evening twilight at ~18:50
Low in the western sky during
evening twilight at ~18:40
Not visible
Not visible
1-23
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
1-10
This comet begins the month in Lynx at magnitude 13.3. Look for
a 1' coma, diffuse condensation at center. It should brighten slowly. FINDER
CHART
Latitude
Visibility September 28
Visibility October 5
Visibility October 12
Visibility October 19
Visibility October 26
Nights Visible
55o
N
High during morning twilight at
~04:00
High during morning twilight at
~04:10
High during morning twilight at
~04:30
High during morning twilight at
~04:50
High in moonlight at ~04:30
1-
40o
N
High during morning twilight at
~04:30
High during morning twilight at
~04:30
High at ~04:40
High during morning twilight at
~04:50
High in moonlight at ~04:40
1-
Equator
Fairly high during morning
twilight at ~04:40
Fairly high during morning
twilight at ~04:40
Fairly high during morning
twilight at ~04:40
Not visible
Fairly high in moonlight at
~04:30
1-
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
This comet begins the month in Scorpius at magnitude 13.4. Look
for a 40" coma, diffuse condensation at center. It should fade slowly,
moving into Sagittarius by month's end. The best visibility is early in the
month as seen from the southern hemisphere. FINDER
CHART
Latitude
Visibility September 28
Visibility October 5
Visibility October 12
Visibility October 19
Visibility October 26
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
High during evening twilight at
~19:00
High during evening twilight at
~19:00
High during evening twilight at
~18:50
Fairly high during evening
twilight at ~18:50
Fairly high during evening
twilight at ~18:50
1-
30o S
High during evening twilight at
~19:20
High during evening twilight at
~19:20
High during evening twilight at
~19:30
High during evening twilight at
~19:30
High during evening twilight at
~19:40
1-
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 |
October 1st |
October 15th |
October 31st |
Observations as of (UT) | |||
Mag | Diam | Mag | Diam | Mag | Diam | |||
C/2023 A3 (Tsuchinshan-ATLAS) | Leo | 2.8 | 4.5' | 3.1 | 7.1' | 5.9 | 3.7' | 2024 September 29 |
13P/Olbers | Virgo | 9.3 | 3.6' | 9.9 | 3.3' | 10.5 | 3.1' | 2024 September 28 |
12P/Pons-Brooks | Centaurus | 11.7 | 5.4' | 12.1 | 5.0' | 12.6 | 4.6' | 2024 September 23 |
C/2022 E2 (ATLAS) | Lynx | 13.3 | 53" | 13.1 | 56" | 13.0 | 1.0' | 2024 September 28 |
C/2023 C2 (ATLAS) | Scorpius | 13.4 | 39" | 13.5 | 37" | 13.6 | 35" | 2024 September 5 |
C/2023 R2 (PANSTARRS) | Virgo | 13.5? | 33"? | 14? | 30"? | 15? | 28"? | 2024 May 1 |
C/2021 G2 (Atlas) | Virgo | 14.4 | 47" | 14.5 | 46" | 14.5 | 46" | 2024 August 29 |
29P/Schwassmann-Wachmann | Leo | 14? | 1.3'? | 14? | 1.3'? | 14? | 1.4'? | 2024 June 12 |
C/2020 V2 (ZTF) | Indus | 14.5 | 1.1' | 14.7 | 1.0' | 14.9 | 57" | 2024 August 30 |
C/2021 S3 (PANSTARRS) | Cygnus | 14.6 | 1.0' | 14.9 | 57" | 15.2 | 53" | 2024 September 27 |
37P/Forbes | Scorpius | 14.8 | 44" | 14.8 | 42" | 15.0 | 40" | 2024 September 1 |
C/2024 G3 (ATLAS) | Centaurus | 14.9 | 34" | 14.4 | 35" | 13.7 | 37" | 2024 September 9 |
C/2022 N2 (PANSTARRS) | Aquarius | 15.0 | 41" | 15.0 | 40" | 15.0 | 39" | 2024 September 22 |
146P/Shoemaker-LINEAR | Orion | 15.3 | 52" | 15.4 | 54" | 15.5 | 56" | 2024 September 14 |
C/2017 K2 (PANSTARRS) | Gemini | 15.4 | 60" | 15.5 | 1.0' | 15.5 | 1.0' | 2024 September 22 |
130P/McNaught-Hughes | Cetus | 15.6 | 50" | 15.8 | 50" | 16.2 | 48" | 2024 July 31 |
P/1906 UA (Scheila) | Taurus | 15.7 | 43" | 15.5 | 46" | 15.4 | 49" | 2017 August 1 |
C/2022 QE78 (ATLAS) | Monoceros | 15.8 | 28" | 15.7 | 29" | 15.5 | 30" | 2024 September 28 |
C/2019 U5 (PANSTARRS) | Puppis | 15.8 | 43" | 15.9 | 43" | 15.9 | 43" | 2024 September 4 |
C/2023 Q1 (PANSTARRS) | Camelopardalis | 16.2 | 29" | 16.1 | 31" | 15.9 | 33" | 2024 September 21 |
P/2012 US27 (Siding Spring) | Orion | 16.4 | 23" | 16.1 | 26" | 15.9 | 29" | 2024 September 27 |
C/2024 M1 (ATLAS) | Canis Major | 17.0 | 25" | 16.5 | 29" | 15.9 | 36" | 2024 September 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
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