Comet Chasing in September Comet chasing is the visual
observation of telescopic comets. Jump to: Observing
synopses Summary data
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13P/Olbers
C/2023 A3
(Tsuchinshan-ATLAS) has the
potential to be a relatively bright interesting comet at the end of
September. It will reach perihelion on September
28, 2024.Visibility in the northern hemisphere will be post perihelion
(October).
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
C/2023 C2 (ATLAS) will reach perihelion in mid November. It is predicted to reach maximum brightness of magnitude
13 in late October.
C/2021 G2 (Atlas) will reach perihelion in early September.
C/2023 V4 (Camarasa-Duszanowicz) is past perihelion, which occurred in late May 2024.
It is fading.
C/2023 R2 (PANSTARRS) will reach perihelion on August 12. It is predicted to reach maximum brightness of magnitude
12 in mid August.
479P/Elenin passed perihelion in early May. Also in early May this comet passed within 0.6 AU of the earth.
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 September
Explanation
of Comet Synopses and charts (read this if you have questions) C/2023 A3
(Tsuchinshan-ATLAS): A morning comet visible in binoculars 13P/Olbers: An evening
comet visible in binoculars at a dark site, or a small telescope under a country
sky 12P/Pons-Brooks: A
southern hemisphere evening comet visible in an 8-inch (20 cm) telescope at a
dark site C/2022 E2 (ATLAS): A
northern hemisphere morning comet visible in a 10-inch (25 cm) telescope at a
dark site, or a 24-inch telescope 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 18-inch (46 cm) under a country sky Summary
Data for This Month's Telescopic Comets
This month there is one
comet visible in binoculars and
one visible in small telescopes.
More are visible in larger instruments. See
the Observing
Synopses for which comets are visible from your latitude, the best
dates and the time of night.
passed
perihelion in late June.
This comet begins the month in Sextans at magnitude 6.7. Look
for a 6.5' coma, condensation is a diffuse spot in coma center; moderately
condensed. It should brighten rapidly, moving into Leo by month's end. FINDER
CHART
Latitude
Visibility August 31
Visibility September 7
Visibility September 14
Visibility September 21
Visibility September 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
Very low in the eastern sky
during morning twilight at ~05:10
21-
Equator
Not visible
Not visible
Not visible
Low in the eastern sky during
morning twilight at ~05:10
Low in the eastern sky during
morning twilight at ~05:10
13-
30o S
Not visible
Not visible
Very low in the eastern sky
during morning twilight at ~05:20
Low in the eastern sky during
morning twilight at ~05:10
Low in the eastern sky during
morning twilight at ~05:00
11-
This comet begins the month in Coma Berenices at magnitude 8.2.
Look for a 3.5' coma, condensation is a diffuse spot in coma center; moderately
condensed. It should fade by about 1.3 magnitudes, moving into Virgo by month's
end. FINDER CHART
Latitude
Visibility August 31
Visibility September 7
Visibility September 14
Visibility September 21
Visibility September 28
Nights Visible
55o
N
Low in the western sky during
evening twilight at ~20:20
Low in the western sky during
evening twilight at ~20:00
Not visible
Not visible
Not visible
1-
40o
N
Fairly high in the western sky
during evening twilight at ~19:40
Fairly high in the western sky
during evening twilight at ~19:30
Fairly high in the western sky
during evening twilight at ~19:10
Low in the western sky during
evening twilight at ~19:00
Not visible
1-
Equator
Fairly high in the western sky
during evening twilight at ~19:00
Fairly high in the western sky
during evening twilight at ~19:00
Fairly high in the western sky
during evening twilight at ~18:50
Fairly high in the western sky
during evening twilight at ~18:50
Not visible
1-
30o S
Low in the western sky during
evening twilight at ~18:40
Low in the western sky during
evening twilight at ~18:40
Not visible
Not visible
Not visible
1-
This comet begins the month in Centaurus at magnitude 10.7. Look
for a 3' coma, center much brighter than edges, though still diffuse. It should
fade by about 1.2 magnitudes by month's end. The best visibility is early in the
month as seen from the southern hemisphere. FINDER
CHART
Latitude
Visibility August 31
Visibility September 7
Visibility September 14
Visibility September 21
Visibility September 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
Not visible
30o S
Fairly high in the western sky
during evening twilight at ~19:00
Fairly high in the western sky
during evening twilight at ~19:00
Fairly high in the western sky
during evening twilight at ~19:00
Not visible
Not visible
1-
This comet begins the month in Lynx at magnitude 13.5. Look for
a 55" coma, diffuse condensation at center. It should brighten slowly.
FINDER CHART
Latitude
Visibility August 31
Visibility September 7
Visibility September 14
Visibility September 21
Visibility September 28
Nights Visible
55o
N
Fairly high during morning
twilight at ~03:00
High during morning twilight at
~03:20
High during morning twilight at
~03:30
High during morning twilight at
~03:50
High during morning twilight at
~04:00
1-
40o
N
Fairly high during morning
twilight at ~04:00
High during morning twilight at
~04:10
High during morning twilight at
~04:10
High during morning twilight at
~04:20
High during morning twilight at
~04:30
1-
Equator
Not visible
Not visible
Fairly high in the northern sky
during morning twilight at ~04:50
Not visible
Fairly high during morning
twilight at ~04:40
1-
30o S
Not visible
Not visible
Not visible
Not visible
Not visible
This comet begins the month in Norma at magnitude 13.3. Look for
a 35" coma, diffuse condensation at center. It should remain constant,
moving into Scorpius by month's end. The best visibility is early in the month
as seen from the southern hemisphere. FINDER
CHART
Latitude
Visibility August 31
Visibility September 7
Visibility September 14
Visibility September 21
Visibility September 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
Fairly high during evening
twilight at ~19:10
High during evening twilight at
~19:10
High during evening twilight at
~19:00
High during evening twilight at
~19:00
High during evening twilight at
~19:00
1-
30o S
High at ~19:10
High during evening twilight at
~19:10
High during evening twilight at
~19:10
High during evening twilight at
~19:10
High during evening twilight at
~19:20
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 |
September 1st |
September 15th |
September 30th |
Observations as of (UT) | |||
| Mag | Diam | Mag | Diam | Mag | Diam | |||
| C/2023 A3 (Tsuchinshan-ATLAS) | Sextans | 6.7 | 3.3' | 4.9 | 4.1' | 2.8 | 7.1' | 2024 August 1 |
| 13P/Olbers | Coma Berenices | 8.2 | 3.7' | 8.8 | 3.5' | 9.5 | 3.2' | 2024 August 30 |
| 12P/Pons-Brooks | Centaurus | 10.7 | 3.0' | 11.3 | 2.7' | 11.8 | 2.4' | 2024 August 30 |
| C/2023 C2 (ATLAS) | Norma | 13.3 | 37" | 13.4 | 35" | 13.4 | 34" | 2024 August 30 |
| C/2022 E2 (ATLAS) | Lynx | 13.5 | 46" | 13.4 | 49" | 13.3 | 52" | 2024 August 29 |
| C/2021 S3 (PANSTARRS) | Cygnus | 14.0 | 1.3' | 14.3 | 1.3' | 14.6 | 1.2' | 2024 August 30 |
| C/2023 V4 (Camarasa-Duszanowicz) | Bootes | 14.1 | 2.2' | 14.8 | 2.0' | 15.4 | 1.8' | 2024 August 29 |
| C/2020 V2 (ZTF) | Indus | 14.2 | 1.2' | 14.4 | 1.1' | 14.5 | 1.1' | 2024 August 30 |
| C/2021 G2 (Atlas) | Virgo | 14.3 | 49" | 14.4 | 48" | 14.4 | 47" | 2024 August 29 |
| 29P/Schwassmann-Wachmann* | Leo | 14.5 | 1.3' | 14.5 | 1.3' | 14.4 | 1.3' | 2024 June 12 |
| 146P/Shoemaker-LINEAR | Orion | 14.8 | 47" | 14.8 | 49" | 14.9 | 52" | 2024 August 28 |
| 37P/Forbes | Libra | 15.0 | 39" | 14.9 | 38" | 14.8 | 37" | 2024 August 30 |
| C/2022 N2 (PANSTARRS) | Aquarius | 15.2 | 40" | 15.1 | 41" | 15.0 | 41" | 2024 August 30 |
| 130P/McNaught-Hughes | Cetus | 15.4 | 46" | 15.5 | 48" | 15.6 | 50" | 2024 July 31 |
| 154P/Brewington | Auriga | 15.4 | 56" | 15.9 | 57" | 16.5 | 58" | 2024 August 30 |
| C/2024 G3 (ATLAS) | Centaurus | 15.8 | 28" | 15.5 | 28" | 15.0 | 29" | 2024 August 26 |
| 89P/Russell | Aquarius | 15.9 | 36" | 16.2 | 35" | 16.5 | 33" | 2024 August 30 |
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
|