Comet Chasing in August

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

News

There is one comet visible in small telescopes in August, but many more are visible in larger instruments.

  • C/2021 O1 (Nishimura) is a new discovery on July 21 by H. Nishimura. It was found very low in morning twilight. It will remain low in the sky throughout the month, reaching magnitude 9 on August 12 (at perihelion of 0.8 AU), but will be difficult to observe. By the time it is observable again after the beginning of the year it will lilkely have faded. 

  • C/2014 UN271 (Bernardinelli-Bernstein) is an interesting Oort cloud comet that was recently 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 is unusually bright for its distance, so it is either intrinsically bright or unusually large for a comet. 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. 

  • C/2019 L3 (ATLAS) will reach perihelion on 2022 January 9, when it may be magnitude 11.

  • 4P/Faye will next reach perihelion in early September. It is currentlly predicted to reach maximum brightness of magnitude 11.5 in mid October.

  • 67P/Churyumov-Gerasimenko will next reach perihelion in early November. On November 2 this comet will pass within 0.4 AU of the earth when It is currently predicted to reach maximum brightness of magnitude 10.3. 

  • 15P/Finlay passed perihelion on July 13. 

  • 2020 T2 (Palomar) passed perihelion in mid July.  

  • 2020 J1 (SONEAR) passed perihelion in mid April.

  • C/2017 K2 (PANSTARRS) will reach perihelion in mid December 2022. It is predicted to reach maximum brightness of magnitude 6.5 in mid January 2023.

  • 6P/d'Arrest will next reach perihelion in mid September when it is predicted to reach maximum brightness of magnitude 10.8. 

  • 7P/Pons-Winnecke passed perihelion in late May. On May 27 this comet passed within 0.4 AU of the earth. It is currently predicted to reach maximum brightness of magnitude 11.2 in early June.

  • C/2020 R4 (Atlas) passed perihelion in early March. On March 1, this comet passed within 0.5 AU of the earth. This comet had an outburst in late April, brightening by as much as a magnitude. 

  • C/2021 A1 (Leonard) was discovered on January 3 by by G. J. Leonard at Mount Lemmon Observatory. It will reach perihelion on January 3, 2022. It may become visible to the naked eye in mid December 2021. It is currently very faint and not visualy observable. 

  • C/2021 A2 (NEOWISE) passed perihelion in late January. In early February this comet will pass within 0.5 AU of the earth. It is currently predicted to reach a maximum brightness of magnitude 11 in early February.

  • C/2021 A4 (NEOWISE) passed perihelion in mid-March.

  • 10P/Tempel passed perihelion in late March.

  • P/2016 J3 (STEREO) passed perihelion on January 25, when it passed within 0.5 AU of the earth. This comet unexpectedly returned early, based on the orbit that was calculated for it in 2016.

  • 246P/NEAT passed perihelion in late February 2021. It is currently predicted to reach maximum brightness of magnitude 14.7 in late June.

  • 29P/Schwassmann-Wachmann had an outburst on January 15. This comet has frequent outbursts, 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.

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 August

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

C/2020 T2 (Palomar): An evening comet visible in small telescopes
This comet begins the month in Virgo at magnitude 10.0. Look for a 4' coma. It should fade slowly, moving into Libra by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Low in the western sky during evening twilight at ~22:00 Not visible Not visible Not visible Not visible 1-
40o N Fairly high in the western sky during evening twilight at ~20:50 Fairly high in the western sky during evening twilight at ~20:40 Fairly high in the western sky during evening twilight at ~20:30 Fairly high in the western sky during evening twilight at ~20:10 Low in the western sky during evening twilight at ~20:00 1-
Equator High at ~19:20 High at ~19:20 High during evening twilight at ~19:20 High during evening twilight at ~19:10 High at ~19:10 1-
30o S High at ~18:50 High at ~19:00 High during evening twilight at ~19:00 High during evening twilight at ~18:50 High at ~19:00 1-

15P/Finlay: A morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Taurus at magnitude 11.0. Look for a 7.5' coma. It should fade by about 1.0 magnitudes, moving into Gemini by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Low in the eastern sky during morning twilight at ~01:50 Low in the eastern sky during morning twilight at ~02:00 Fairly high in the eastern sky during morning twilight at ~02:10 Fairly high in the eastern sky during morning twilight at ~02:40 Fairly high in the eastern sky during morning twilight at ~02:50 1-
40o N Fairly high in the eastern sky during morning twilight at ~03:20 Fairly high in the eastern sky during morning twilight at ~03:30 Fairly high during morning twilight at ~03:40 Fairly high during morning twilight at ~03:50 Fairly high during morning twilight at ~03:50 1-
Equator Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~05:00 Fairly high during morning twilight at ~04:50 1-
30o S Fairly high in the northern sky during morning twilight at ~05:30 Fairly high in the northern sky during morning twilight at ~05:20 Low in the northern sky during morning twilight at ~05:20 Low in the northern sky during morning twilight at ~05:20 Low in the northern sky during morning twilight at ~05:10 1-

C/2017 K2 (PANSTARRS): An evening comet visible in a 10-inch (25 cm) telescope
This comet begins the month in Hercules at magnitude 13.3. Look for a 1' coma. It should brighten slowly.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N High during evening twilight at ~23:20 High during evening twilight at ~22:50 High during evening twilight at ~22:20 High during evening twilight at ~21:30 High during evening twilight at ~21:30 1-
40o N High at ~21:20 High at ~21:00 High at ~21:50 High during evening twilight at ~20:10 High at ~20:20 1-
Equator High at ~20:30 High at ~20:00 High in moonlight at ~19:50 High during evening twilight at ~19:10 High at ~19:20 1-
30o S Fairly high in the northern sky at ~20:30 Fairly high in the northern sky at ~20:00 Fairly high in the northern sky in moonlight at ~19:30 Fairly high in the northern sky during evening twilight at ~18:50 Fairly high in the northern sky during evening twilight at ~19:00 1-

7P/Pons-Winnecke: A southern hemisphere morning comet visible in a 12.5-inch (32 cm) telescope
This comet begins the month in Phoenix at magnitude 13.0. Look for a 2' coma. It should fade rapidly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 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 High in moonlight at ~03:10 High at ~03:00 Fairly high at ~02:30 Fairly high in the southern sky during morning twilight at ~05:00 Fairly high at ~23:20 1-
30o S High at ~01:20 High at ~03:00 High at ~02:30 High during morning twilight at ~05:20 High at ~23:50 1-

C/2019 L3 (ATLAS): A northern hemisphere morning comet visible in a 14-inch (36 cm) telescope
This comet begins the month in Auriga at magnitude 11.9. Look for a 3.5' coma. It should brighten slowly.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Fairly high in the northern sky during morning twilight at ~00:50 Fairly high in the northern sky during morning twilight at ~01:20 Fairly high in the eastern sky during morning twilight at ~01:50 Fairly high during morning twilight at ~02:40 Fairly high during morning twilight at ~02:40 1-
40o N Fairly high in the eastern sky during morning twilight at ~03:10 Fairly high in the eastern sky at ~03:20 Fairly high at ~03:30 Fairly high during morning twilight at ~03:50 High in moonlight at ~03:50 1-
Equator Not visible Low in the northern sky during morning twilight at ~04:50 Low in the northern sky during morning twilight at ~04:50 Fairly high in the northern sky during morning twilight at ~05:00 Fairly high in the northern sky during morning twilight at ~04:50 1-
30o S Not visible Not visible Not visible Not visible Not visible  

4P/Faye: A morning comet visible in a 14-inch (36 cm) telescope
This comet begins the month in Aries at magnitude 12.3. Look for a 3.5' coma. It should brighten by about 0.5 magnitudes, moving into Taurus by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Fairly high in the eastern sky during morning twilight at ~01:20 Fairly high in the eastern sky during morning twilight at ~01:40 Fairly high in the eastern sky during morning twilight at ~02:00 Fairly high during morning twilight at ~02:40 Fairly high during morning twilight at ~02:40 1-
40o N Fairly high during morning twilight at ~03:10 High at ~03:20 High at ~03:30 High during morning twilight at ~03:50 High in moonlight at ~03:40 1-
Equator High in moonlight at ~04:40 High at ~04:50 High at ~04:40 High during morning twilight at ~05:00 High in moonlight at ~04:40 1-
30o S Fairly high in moonlight at ~05:20 Fairly high at ~05:10 Fairly high at ~05:10 Fairly high during morning twilight at ~05:20 Fairly high in moonlight at ~05:00 1-

67P/Churyumov-Gerasimenko: A morning comet visible in a 16-inch (41 cm) telescope
This comet begins the month in Pisces at magnitude 13.7. Look for a 4' coma. It should brighten by about 1.4 magnitudes, moving into Aries by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Not visible Fairly high in the eastern sky during morning twilight at ~01:40 Fairly high during morning twilight at ~02:00 High during morning twilight at ~02:40 High during morning twilight at ~02:40 1-
40o N High in moonlight at ~03:00 High at ~03:20 High at ~03:20 High during morning twilight at ~04:00 High in moonlight at ~03:40 1-
Equator Fairly high in moonlight at ~01:10 High at ~04:40 High at ~04:30 High during morning twilight at ~05:00 Fairly high in moonlight at ~00:50 1-
30o S Fairly high in moonlight at ~01:50 High at ~04:50 High at ~04:40 High during morning twilight at ~05:20 Fairly high in moonlight at ~01:40 1-

C/2020 J1 (SONEAR): An evening comet visible in a 16-inch (41 cm) telescope
This comet begins the month in Virgo at magnitude 13.8. Look for a 1' coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Fairly high in the western sky during evening twilight at ~20:50 Low in the western sky during evening twilight at ~20:40 Low in the western sky during evening twilight at ~20:20 Not visible Not visible 1-
Equator High at ~19:20 High at ~19:20 High during evening twilight at ~19:20 Fairly high during evening twilight at ~19:10 Fairly high during evening twilight at ~19:10 1-
30o S High at ~18:50 High at ~19:00 High during evening twilight at ~18:50 Fairly high during evening twilight at ~18:50 Fairly high during evening twilight at ~19:00 1-

C/2021 O1 (Nishimura): A far-northern morning comet visible in very large telescopes
This comet begins the month in Gemini at magnitude 9.2. Look for a 1.5' coma. It should fade slowly, moving into Leo by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Very low in the northern sky during morning twilight at ~02:10 Very low in the northern sky during morning twilight at ~02:30 Not visible Not visible Not visible 1-10
40o N Very low in the eastern sky during morning twilight at ~03:40 Very low in the eastern sky during morning twilight at ~03:50 Not visible Not visible Not visible 1-9
Equator Not visible Not visible Not visible Not visible Not visible  
30o S Not visible Not visible Not visible Not visible Not visible  

246P/NEAT: An evening comet visible in very large telescopes
This comet begins the month in Sagittarius at magnitude 14.3. Look for a 40" coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky at ~22:10 Low in the southern sky at ~21:40 Low in the southern sky in moonlight at ~21:10 Not visible Low in the southern sky at ~20:20 1-17, 22-
Equator High at ~22:10 High at ~21:40 High at ~22:50 High during evening twilight at ~19:00 High at ~20:20 1-17, 21-
30o S High at ~22:10 High at ~21:40 High at ~23:20 High during evening twilight at ~18:40 High at ~20:20 1-17, 21-

10P/Tempel: A morning comet visible in very large telescopes
This comet begins the month in Taurus at magnitude 14.2. Look for a 1.5' coma. It should fade by about 0.9 magnitudes by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Not visible Low in the eastern sky during morning twilight at ~02:00 Low in the eastern sky during morning twilight at ~02:10 Fairly high in the eastern sky during morning twilight at ~02:40 Fairly high in the eastern sky during morning twilight at ~02:50 5-24, 28-
40o N Fairly high in the eastern sky during morning twilight at ~03:20 Fairly high during morning twilight at ~03:20 Fairly high during morning twilight at ~03:30 High during morning twilight at ~03:50 Not visible 1-23, 29-
Equator High in moonlight at ~04:50 High at ~04:50 High at ~04:50 High during morning twilight at ~05:00 High in moonlight at ~04:40 1-21, 23-23, 28-
30o S High in moonlight at ~05:20 High at ~05:10 High at ~05:10 High during morning twilight at ~05:20 High in moonlight at ~05:00 1-23, 28-

8P/Tuttle: A solar conjunction comet visible in very large telescopes
This comet begins the month in Gemini at magnitude 15.2. Look for a 0" coma. It should brighten by about 0.8 magnitudes, moving into Hydra by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 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 Not visible Not visible Not visible Not visible Not visible  

C/2019 T4 (ATLAS): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Hydra at magnitude 14.5. Look for a 25" coma. It should brighten slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 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 Low in the western sky during evening twilight at ~18:40 Not visible Not visible Not visible Not visible 1-3

C/2020 PV6 (PANSTARRS): An evening comet visible in very large telescopes
This comet begins the month in Lyra at magnitude 14.7. Look for a 25" coma. It should fade slowly, moving into Hercules by month's end.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N High during evening twilight at ~23:20 High during evening twilight at ~23:00 High during evening twilight at ~22:20 High during evening twilight at ~21:30 High during evening twilight at ~21:20 1-
40o N High at ~21:40 High at ~21:00 High at ~21:50 High during evening twilight at ~20:10 High at ~20:20 1-
Equator High at ~21:40 High at ~20:40 High in moonlight at ~20:50 High during evening twilight at ~19:10 High at ~19:20 1-
30o S Fairly high in the northern sky at ~21:40 Fairly high in the northern sky at ~20:40 Fairly high in the northern sky in moonlight at ~20:00 Fairly high during evening twilight at ~18:50 Fairly high at ~19:10 1-

C/2019 F1 (ATLAS-Africano): A southern hemisphere morning comet visible in very large telescopes
This comet begins the month in Octans at magnitude 14.8. Look for a 40" coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 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 at ~01:00 Fairly high at ~01:50 Fairly high at ~00:30 Fairly high during morning twilight at ~05:20 Fairly high at ~22:30 1-

C/2020 F5 (MASTER): A morning comet visible in very large telescopes
This comet begins the month in Sculptor at magnitude 14.9. Look for a 40" coma. It should remain constant, moving into Pisces Austrinus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART

Latitude Visibility July 31 Visibility August 7 Visibility August 14 Visibility August 21 Visibility August 28 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky in moonlight at ~02:50 Low in the southern sky at ~02:20 Low in the southern sky at ~01:50 Not visible Low in the southern sky in moonlight at ~00:30 1-20, 25-
Equator High at ~00:40 High at ~02:20 High at ~01:40 Fairly high in the western sky during morning twilight at ~05:00 High at ~23:00 1-21, 24-
30o S High at ~01:10 High at ~02:20 High at ~01:50 Fairly high during morning twilight at ~05:20 High at ~23:40 1-21, 23-

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

August 1st

August 15th

August 31st

 Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2021 O1 (Nishimura) Gemini 9.2 1.3' 9.0 1.3' 9.5 1.2' 2021 July 26
C/2020 T2 (Palomar) Virgo 10.0 4.0' 10.2 3.7' 10.5 3.4' 2021 July 31
15P/Finlay Taurus 11.0 7.8' 11.4 7.3' 12.0 6.9' 2021 July 22
C/2019 L3 (ATLAS) Auriga 11.9 3.1' 11.7 3.2' 11.6 3.4' 2021 July 17
4P/Faye Aries 12.3 3.2' 12.0 3.5' 11.7 3.8' 2021 July 21
7P/Pons-Winnecke Phoenix 13.0 2.0' 13.7 1.8' 14.6 1.5' 2021 July 31
C/2017 K2 (PANSTARRS) Hercules 13.3 1.1' 13.2 1.1' 13.1 1.1' 2021 July 31
67P/Churyumov-Gerasimenko Pisces 13.7 2.7' 13.0 3.2' 12.2 4.0' 2021 July 21
252P/LINEAR Leo 13.8 36" 14.1 35" 14.6 33" 2016 June 4
C/2020 J1 (SONEAR) Virgo 13.8 1.1' 14.0 58" 14.3 54" 2021 July 31
10P/Tempel Taurus 14.2 1.3' 14.6 1.3' 15.1 1.4' 2021 July 19
246P/NEAT Sagittarius 14.3 38" 14.5 36" 14.7 33" 2021 July 30
C/2019 T4 (ATLAS) Hydra 14.5 26" 14.5 26" 14.4 26" 2021 July 12
C/2020 PV6 (PANSTARRS) Lyra 14.7 26" 14.8 24" 15.0 21" 2021 July 31
C/2019 F1 (ATLAS-Africano) Octans 14.8 39" 14.9 38" 15.0 37" 2021 July 31
C/2020 F5 (MASTER) Sculptor 14.9 39" 14.9 40" 14.9 40" 2021 July 31
C/2018 U1 (Lemmon) Ophiuchus 15.0 33" 15.1 31" 15.2 30" 2021 July 31
8P/Tuttle Gemini 15.2 31" 14.6 32" 14.4 33" 2021 July 27
C/2021 A7 (NEOWISE) Leo 15.2 1.9' 15.3 1.9' 15.5 1.8' 2021 July 9
106P/Schuster Taurus 15.4 32" 15.2 34" 15.1 35" 2021 July 16
17P/Holmes Perseus 15.5 1.4' 15.5 1.5' 15.6 1.5' 2021 July 22
29P/Schwassmann-Wachmann Taurus 15.6 21" 15.5 22" 15.4 23" 2021 July 22
117P/Helin-Roman-Alu Virgo 15.8 1.3' 15.9 1.3' 15.9 1.2' 2021 July 11
C/2020 M5 (ATLAS) Canes Venatici 15.8 1.5' 15.9 1.4' 16.0 1.4' 2021 July 19
C/2020 O2 (Amaral) Ophiuchus 15.9 22" 16.0 21" 16.2 20" 2021 July 8
284P/McNaught Aquarius 16.0 40" 15.9 43" 15.8 45" 2021 July 14
C/2021 A1 (Leonard) Ursa Major 16.7 36" 16.3 38" 15.7 41" 2021 July 5
19P/Borrelly Phoenix 17.0 52" 16.3 57" 15.5 1.0' 2021 July 21
*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 custom charts for your location and telescope/binoculars: software for visual comet observing

New: 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