Comet Chasing in September

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

News

There are two comets visible in small telescopes this month. Many more are visible in larger instruments.

  • C/2017 K2 (PANSTARRS) will reach perihelion in mid December 2022. 

  • 73P/Schwassmann-Wachmann passed perihelion on August 25. It is predicted to reach maximum brightness of magnitude 11.5 in early September. This comet has a long history of fragmentation, and some very faint fragments may have already been identified. 

  • C/2022 P1 (NEOWISE) will next reach perihelion in late November. It was reported to have brightned in late August and is currently predicted to reach maximum brightness of magnitude 13.3 in early November. It appears to be a periodic comet with a period of 94 years, leading to a previous perihelion in approximately 1928.

  • C/2022 E3 (ZTF) will reach perihelion in mid January 2023. On January 12 this comet will pass within 0.3 AU of the earth. It is predicted to reach maximum brightness of magnitude 4.2 in late January.

  • C/2020 V2 (ZTF) will reach perihelion in early May 2023. It is predicted to reach maximum brightness of magnitude 9.5 in early September 2023.

  • 117P/Helin-Roman-Alu passed perihelion in early July. 

  • C/2019 T4 (ATLAS) passed perihelion in early June. 

  • C/2021 O3 (PANSTARRS) passed perihelion on April 21. In early May this comet will pass within 0.6 AU of the earth. It reached maximum brightness of magnitude in late April. 

  • 45P/Honda-Mrkos-Pajdusakova was only recently recovered. It passed perhilion on April 26, and was not seen prior.

  • C/2021 E3 (ZTF) passed perihelion in mid June. 

  • C/2022 E3 (ZTF) (be careful not to confuse with 2021 E3 (ZTF) above) will reach perihelion in mid January 2023. On January 12 this comet will pass within 0.3 AU of the earth. It is currently predicted to reach maximum brightness of magnitude 5.3 in late January.

  • C/2021 P4 (ATLAS) will reach perihelion at the end of July 2022. It is predicted to reach maximum brightness of magnitude 9 in late July..

  • C/2019 L3 (ATLAS) passed perihelion on January 9.

  • 19P/Borrelly passed perihelion in early February and is fading.

  • 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. Recent 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: C/2020 Q1 (Borisov), C/2020 P1 (NEOWISE), and C/2019 Y4 (ATLAS). Beware that various other online 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!

Observing Synopses for September

Explanation of Comet Synopses and charts (read this if you have questions)

C/2017 K2 (PANSTARRS): An evening comet visible in small telescopes
This comet begins the month in Scorpius at magnitude 8.9. Look for a 5' coma. It should remain constant, moving into Lupus by month's end. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky during evening twilight at ~19:50 Low in the southern sky during evening twilight at ~19:30 Very low in the southern sky during evening twilight at ~19:20 Not visible Not visible 1-27
Equator High in moonlight at ~19:10 High during evening twilight at ~19:00 Fairly high at ~19:10 Fairly high during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~19:00 1-
30o S High in moonlight at ~19:10 High during evening twilight at ~19:00 High at ~19:20 High at ~19:20 Fairly high during evening twilight at ~19:20 1-

C/2022 E3 (ZTF): An evening comet visible in small telescopes
This comet begins the month in Hercules at magnitude 12.3. Look for a 55" coma. It should brighten by about 0.8 magnitudes, moving into Corona Borealis by month's end.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N High during evening twilight at ~21:00 High during evening twilight at ~20:20 High during evening twilight at ~20:20 Fairly high during evening twilight at ~19:50 Fairly high during evening twilight at ~19:30 1-
40o N High in moonlight at ~20:10 High during evening twilight at ~19:40 High at ~19:40 High at ~19:20 High during evening twilight at ~19:10 1-
Equator High in moonlight at ~19:10 High during evening twilight at ~19:00 High at ~19:10 Fairly high during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~19:00 1-
30o S Fairly high in the northern sky during evening twilight at ~19:00 Fairly high in the northern sky during evening twilight at ~19:00 Low in the northern sky during evening twilight at ~19:10 Low in the northern sky during evening twilight at ~19:10 Not visible 1-

73P/Schwassmann-Wachmann: An evening comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Virgo at magnitude 11.5. Look for a 55" coma. It should fade by about 0.6 magnitudes, moving into Scorpius by month's end. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 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 Fairly high during evening twilight at ~19:00 Fairly high at ~19:10 Fairly high at ~19:00 Fairly high in moonlight at ~19:00 1-
30o S High during evening twilight at ~19:00 High during evening twilight at ~19:00 High at ~19:10 High at ~19:20 High in moonlight at ~19:20 1-

C/2019 L3 (ATLAS): A morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Hydra at magnitude 11.3. Look for a 2.5' coma. It should fade slowly.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Not visible Not visible Not visible Not visible Low in the eastern sky during morning twilight at ~04:40 22-
Equator Not visible Low in the eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:40 Fairly high in the eastern sky during morning twilight at ~04:40 1-
30o S Low in the eastern sky during morning twilight at ~05:00 Low in the eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight at ~04:40 Fairly high in the eastern sky during morning twilight at ~04:30 Fairly high in the eastern sky during morning twilight at ~04:20 1-

C/2020 V2 (ZTF): A northern hemisphere morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Ursa Major at magnitude 12.5. Look for a 1.5' coma. It should brighten by about 0.6 magnitudes by month's end.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Fairly high in the northern sky during morning twilight at ~03:00 Fairly high in the northern sky during evening twilight at ~20:20 Fairly high in moonlight at ~03:30 Fairly high at ~03:50 High at ~04:00 1-
40o N Low in the northern sky during morning twilight at ~04:00 Fairly high in the northern sky during morning twilight at ~04:10 Fairly high in the northern sky during morning twilight at ~04:10 Fairly high during morning twilight at ~04:20 Fairly high at ~04:30 1-
Equator Not visible Not visible Not visible Not visible Not visible 30-
30o S Not visible Not visible Not visible Not visible Not visible  

C/2022 P1 (NEOWISE): An evening comet visible in a 16-inch (41 cm) telescope
This comet begins the month in Cetus at magnitude 13.3. Look for a 5.5' coma. It should brighten by about 1.2 magnitudes, moving into Sculptor by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Fairly high at ~02:50 Not visible Low in the southern sky in moonlight at ~01:20 Not visible Not visible 1-10, 12-23
40o N High at ~03:20 Not visible Fairly high in moonlight at ~01:00 Fairly high in the southern sky at ~00:00 Low in the southern sky at ~22:40 1-
Equator High at ~03:30 Not visible High at ~00:10 High at ~00:10 High at ~22:50 1-9, 13-
30o S High at ~03:30 Not visible High at ~01:20 High at ~00:10 High at ~23:40 1-9, 12-

C/2020 K1 (PANSTARRS): An evening comet visible in a 16-inch (41 cm) telescope
This comet begins the month in Ophiuchus at magnitude 13.6. Look for a 55" coma. It should remain constant.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Fairly high in the southern sky during evening twilight at ~21:00 Fairly high in the southern sky during evening twilight at ~20:20 Fairly high in the southern sky during evening twilight at ~20:10 Low in the southern sky during evening twilight at ~19:50 Low in the southern sky during evening twilight at ~19:30 1-
40o N Fairly high at ~21:20 High during evening twilight at ~19:40 Fairly high at ~19:40 Fairly high at ~19:30 Fairly high in the western sky in moonlight at ~19:10 1-
Equator High in moonlight at ~19:20 High during evening twilight at ~19:00 High at ~19:10 High at ~19:10 High in moonlight at ~19:10 1-
30o S High in moonlight at ~19:10 High during evening twilight at ~19:00 High at ~19:20 High at ~19:20 High in moonlight at ~19:20 1-

C/2021 E3 (ZTF): A southern hemisphere morning comet visible in very large telescopes
This comet begins the month in Antlia at magnitude 12.1. Look for a 2.5' coma. It should fade by about 0.7 magnitudes by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 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 Low in the eastern sky during morning twilight at ~04:40 28-
30o S Low in the eastern sky during morning twilight at ~05:00 Low in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:40 Fairly high in the eastern sky during morning twilight at ~04:30 Fairly high in the eastern sky at ~04:20 1-

C/2019 T4 (ATLAS): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Virgo at magnitude 13.1. Look for a 1.5' coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 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 Low in the western sky during evening twilight at ~19:10 Not visible Not visible Not visible Not visible 1-7, 11-11
30o S Low in the western sky during evening twilight at ~19:00 Not visible Not visible Not visible Not visible 1-7, 11-12

C/2019 U5 (PANSTARRS): A northern hemisphere evening comet visible in very large telescopes
This comet begins the month in Coma Berenices at magnitude 14.0. Look for a 50" coma. It should remain constant.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Low in the western sky during evening twilight at ~20:50 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 1-21, 23-23
40o N Fairly high in the western sky during evening twilight at ~20:00 Low in the western sky during evening twilight at ~19:40 Low in the western sky during evening twilight at ~19:30 Low in the western sky during evening twilight at ~19:10 Not visible 1-25
Equator 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 Not visible Not visible 1-15
30o S Not visible Not visible Not visible Not visible Not visible  

116P/Wild: A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Virgo at magnitude 14.1. Look for a 50" coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 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 Low in the western sky during evening twilight at ~19:10 Not visible Not visible Not visible Not visible 1-6, 11-12
30o S 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 Not visible 1-7, 10-14

117P/Helin-Roman-Alu: An evening comet visible in very large telescopes
This comet begins the month in Sagittarius at magnitude 14.1. Look for a 50" coma. It should fade slowly. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky in moonlight at ~20:10 Low in the southern sky during evening twilight at ~19:40 Low in the southern sky during evening twilight at ~19:20 Low in the southern sky during evening twilight at ~19:10 Low in the southern sky during evening twilight at ~19:00 1-
Equator Fairly high in moonlight at ~23:10 High during evening twilight at ~19:00 High at ~19:20 High at ~19:10 High in moonlight at ~19:10 1-
30o S Fairly high in moonlight at ~00:10 High during evening twilight at ~18:50 High at ~19:20 High at ~19:30 High in moonlight at ~19:30 1-

C/2020 R7 (ATLAS): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Scorpius at magnitude 14.1. Look for a 55" coma. It should fade slowly. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 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 in moonlight at ~19:20 High during evening twilight at ~19:00 High at ~19:10 High at ~19:10 Fairly high in moonlight at ~19:00 1-
30o S High in moonlight at ~19:10 High during evening twilight at ~19:00 High at ~19:20 High at ~19:20 High in moonlight at ~19:30 1-

29P/Schwassmann-Wachmann: A morning comet visible in very large telescopes
This comet begins the month in Auriga at magnitude 15.1. Look for a 1.5' coma. It should brighten slowly, moving into Gemini by month's end.  FINDER CHART

Latitude Visibility September 3 Visibility September 10 Visibility September 17 Visibility September 24 Visibility October 1 Nights Visible
55o N Fairly high during morning twilight at ~03:00 Not visible Not visible High at ~03:40 High at ~03:50 1-8, 19-
40o N High at ~03:50 Not visible Not visible High at ~04:10 High at ~04:20 1-8, 19-
Equator Fairly high at ~04:40 Not visible Not visible High at ~04:40 High at ~04:30 1-7, 19-
30o S Not visible Not visible Not visible Not visible Fairly high in the northern sky at ~04:20 27-27, 30-

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

September 1st

September 15th

September 30th

 Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2017 K2 (PANSTARRS) Scorpius 8.9 5.1' 8.9 4.8' 9.0 4.5' 2022 August 31
C/2021 P4 (ATLAS) Crater 10.6 2.7' 11.2 2.6' 11.8 2.5' 2022 June 30
C/2019 L3 (ATLAS) Hydra 11.3 2.2' 11.3 2.2' 11.4 2.3' 2022 June 21
73P/Schwassmann-Wachmann Virgo 11.5 53" 11.6 56" 12.1 55" 2022 July 31
C/2021 E3 (ZTF) Antlia 12.1 2.8' 12.5 2.6' 12.9 2.5' 2022 June 25
C/2022 E3 (ZTF) Hercules 12.3 57" 11.9 56" 11.5 55" 2022 August 31
C/2020 V2 (ZTF) Ursa Major 12.5 1.1' 12.3 1.2' 12.0 1.3' 2022 August 31
C/2019 T4 (ATLAS) Virgo 13.1 1.3' 13.1 1.3' 13.2 1.3' 2022 July 25
C/2022 P1 (NEOWISE) Cetus 13.3 4.0' 12.5 5.2' 12.2 5.6' 2022 September 1
C/2020 K1 (PANSTARRS) Ophiuchus 13.6 58" 13.6 56" 13.6 53" 2022 August 1
C/2021 F1 (Lemmon-PANSTARRS) Dorado 14.0 4.0' 14.5 3.7' 15.0 3.3' 2022 August 8
C/2019 U5 (PANSTARRS) Coma Berenices 14.0 50" 14.0 49" 13.9 49" 2022 August 19
C/2020 R7 (ATLAS) Scorpius 14.1 1.0' 14.3 56" 14.4 51" 2022 August 20
117P/Helin-Roman-Alu Sagittarius 14.1 54" 14.2 51" 14.4 47" 2022 August 23
116P/Wild Virgo 14.1 48" 14.3 46" 14.4 45" 2022 August 20
22P/Kopff Pisces 14.2 4.3' 14.5 4.4' 14.8 4.3' 2022 August 31
81P/Wild Cancer 14? 50"? 14? 52"? 13? 55"? 2022 March 22
19P/Borrelly Leo 14.5? 1.6'? 14.7? 1.5'? 14.9? 1.5'? 2022 May 25
C/2020 Y2 (ATLAS) Puppis 15.1? 26"? 15.1? 27"? 15.1? 28"? 2022 May 6
29P/Schwassmann-Wachmann Auriga 15.1 1.6' 15.1 1.7' 15.0 1.7' 2022 August 31
169P/NEAT Leo 15.7 1.8' 16.2 1.7' 16.6 1.6' 2022 June 29
9P/Tempel Pisces Austrinus 15.9 1.9' 16.3 1.7' 16.9 1.5' 2022 August 31
119P/Parker-Hartley Gemini 15.9 1.7' 15.8 1.8' 15.7 1.9' 2022 August 17
327P/Van Ness Pisces 16.0 58" 15.9 1.0' 16.0 1.0' 2022 August 29
285P/LINEAR Ophiuchus 16.0 35" 15.9 34" 15.8 33" 2022 August 30
P/2022 L3 (ATLAS) Aries 16.2 29" 16.0 32" 15.7 35" 2022 July 28
C/2021 X1 (Maury-Attard) Canis Major 16.3 31" 16.1 33" 15.9 36" 2022 August 9
C/2021 Y1 (ATLAS) Auriga 16.4 24" 16.0 26" 15.6 30" 2022 August 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