Comet Chasing in October


Comet chasing is the visual observation of telescopic comets.  Jump to:  Observing synopses    Summary data    Buy me a Coffee 

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.

Notable photo opportunity: C/2023 A3 (Tsuchinshan-ATLAS) willl be very close to the globular cluster M5 on the evening of October 16. Nearby will be comet 13P/Olbers. There may bee to much difference in size and brightness in the objects, which may make it technically difficult, but it is worth a try. See the finder chart for 13P/Olbers below. 

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
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-

13P/Olbers: An evening comet visible in small telescopes at a dark site, or a 10-inch (25 cm) under a country sky
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

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
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  

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
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-

Summary Data for This Month's Telescopic Comets


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
*In solar conjunction and generally not visible 

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
Skyhound's Guide to Finding Comets
BAA Comet Section
Weekly Information About Bright Comets
Cometography