Comet Chasing in August


Comet chasing is the visual observation of telescopic comets.

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August offers a binocular comet, and a total of six comets visible in small telescopes.
  • C/2020 F3 (NEOWISE) passed perihelion in early July. In late July this comet will passed within 0.7 AU of the earth. Although past its prime and in moonlight early in the month, it is expected to be a near-naked eye and very good binocular object after the moon leaves the early evening view. The dist tail has dropped off substantially, but as of July 29, it was still visible as a wide, shuttle-cock shape. 

  • A/2019 U6 (Lemmon). This former asteroid was observed to have a cometary coma in early February, apparently noted by A. Novichonok. It passed perihelion on June 18. 

  • 88P/Howell will reach perihelion in late September. It is predicted to reach maximum brightness of magnitude 9.5 in mid September

  • C/2017 T2 (PANSTARRS) passed perihelion in early May. 

  • C/2019 N1 (ATLAS) will reach perihelion in early December. It is currently predicted to reach a maximum brightness of magnitude 9.7 in early January 2021.

  • 246P/NEAT will next reach perihelion in late February 2021. It is currently predicted to reach maximum brightness of magnitude 12.7 in late June.

  • C/2020 F8 (SWAN) was discovered on SWAN images on April 9. It passed perihelion on May 26 and  in late May it passed within 0.8 AU of the earth. It is currently a naked-eye object..

  • 2P/Encke passed perihelion on June 25. In late July this comet passed within 0.6 AU of the earth. 

  • 58P/Jackson-Neujmion passed perihelion in late May. 

  • C/2017 T2 (PANSTARRS): passed perihelion in early May.

  • C/2019 Y1 (ATLAS) passed perihelion in March.

  • C/2018 F4 (PANSTARRS) passed perihelion last December.

  • C/2019 Y4 (ATLAS). This comet had the potential to become a bright naked-eye object near perihelion in late May, but on April 8 it was observed in images to have fragmented. It has not been observed since late May and is presumed lost. 

  • 2I/Borisov (formerly C/2019 Q4) is the first interstellar comet, discovered on August 30, 2019 by G. Borisov. It took until September 10/11 for the interstellar nature of this comet to become readily apparent. On September 24 the IAU officially recognized it as interstellar and assigned a new designation. It will reach perihelion in early December, when it will come within 1.9 AU of the sun and earth. At that time it will be in Hydra. It isn't yet clear how bright it will become, but with comets there is always the possibility that it will brighten enough to be observable visually in large instruments. More here...

  • 29P/Schwassmann-Wachmann This comet has 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.

C/2020 F3 (NEOWISE) on the evening of July 29, in moonlight, from Cloudcroft, New Mexcio.  

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!

Comet Synopses for August


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

C/2020 F3 (NEOWISE): An evening comet visible in binoculars
This comet begins the month in Coma Berenices at magnitude 5.4. Look for a 4' coma. It should fade rapidly, moving into Virgo by month's end.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Low in the western sky during evening twilight at ~22:10 Low in the western sky during evening twilight at ~21:50 Low in the western sky during evening twilight at ~21:40 Very low in the western sky during evening twilight at ~21:10 Not visible 1-
40o N Fairly high during evening twilight at ~20:40 Fairly high in the western sky during evening twilight at ~20:50 Fairly high in the western sky during evening twilight at ~20:30 Fairly high in the western sky during evening twilight at ~20:20 Not visible 1-
Equator Fairly high during evening twilight at ~19:10 High at ~19:20 High at ~19:20 High in moonlight at ~19:20 High during evening twilight at ~19:00 1-
30o S Fairly high in the northern sky during evening twilight at ~18:30 Fairly high at ~19:00 Fairly high at ~19:00 Fairly high in moonlight at ~19:00 Fairly high during evening twilight at ~18:50 1-

C/2019 U6 (Lemmon): An evening comet visible in small telescopes
This comet begins the month in Coma Berenices at magnitude 9.2. Look for a 2' coma. It should fade rapidly, moving into Bootes by month's end.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Fairly high in the western sky during evening twilight at ~22:00 Fairly high in the western sky during evening twilight at ~21:50 Fairly high in the western sky during evening twilight at ~22:00 Fairly high in the western sky during evening twilight at ~21:40 Fairly high during evening twilight at ~20:50 1-
40o N Fairly high during evening twilight at ~20:40 Fairly high during evening twilight at ~20:50 Fairly high at ~20:40 Fairly high at ~20:30 High during evening twilight at ~20:00 1-
Equator High during evening twilight at ~19:10 High at ~19:30 High at ~19:20 High in moonlight at ~19:20 High during evening twilight at ~19:10 1-
30o S Fairly high during evening twilight at ~18:40 Fairly high at ~19:00 Fairly high in the northern sky at ~19:00 Fairly high in the northern sky in moonlight at ~19:00 Fairly high in the northern sky during evening twilight at ~18:50 1-

88P/Howell: An evening comet visible in small telescopes
This comet begins the month in Virgo at magnitude 10.0. Look for a 3.5' coma. It should brighten slowly, moving into Libra by month's end. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible 1-1, 3-4
40o N Low in the western sky during evening twilight at ~20:30 Low in the western sky during evening twilight at ~20:40 Low in the western sky during evening twilight at ~20:20 Low in the western sky during evening twilight at ~20:10 Low in the western sky during evening twilight at ~19:40 1-
Equator High during evening twilight at ~19:10 High at ~19:30 High at ~19:20 High in moonlight at ~19:20 High during evening twilight at ~19:00 1-
30o S High during evening twilight at ~18:40 High at ~19:00 High at ~19:00 High in moonlight at ~19:00 High during evening twilight at ~18:50 1-

2P/Encke: An evening comet visible in small telescopes
This comet begins the month in Corvus at magnitude 9.5. Look for a 1' coma. It should fade rapidly, moving into Lupus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Not visible Very low in the western sky during evening twilight at ~20:00 Very low in the southern sky during evening twilight at ~20:00 Very low in the southern sky during evening twilight at ~20:00 Low in the southern sky during evening twilight at ~19:40 1-
Equator Fairly high during evening twilight at ~19:10 Fairly high during evening twilight at ~19:20 High during evening twilight at ~19:20 High during evening twilight at ~19:20 High during evening twilight at ~19:00 1-
30o S High during evening twilight at ~18:40 High at ~18:50 High at ~19:00 High in moonlight at ~19:00 High during evening twilight at ~18:50 1-

C/2017 T2 (PANSTARRS): An evening comet visible in small telescopes
This comet begins the month in Coma Berenices at magnitude 10.1. Look for a 60" coma. It should fade by about 1.0 magnitudes, moving into Virgo by month's end.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Fairly high in the western sky during evening twilight at ~22:00 Low in the western sky during evening twilight at ~21:50 Low in the western sky during evening twilight at ~21:40 Low in the western sky during evening twilight at ~21:10 Low in the western sky during evening twilight at ~20:30 1-
40o N Fairly high during evening twilight at ~20:40 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 ~20:20 Fairly high in the western sky during evening twilight at ~19:50 1-
Equator High during evening twilight at ~19:10 High at ~19:20 High at ~19:20 Fairly high in moonlight at ~19:20 Fairly high during evening twilight at ~19:00 1-
30o S Fairly high during evening twilight at ~18:40 Fairly high at ~18:50 Fairly high at ~19:00 Fairly high during evening twilight at ~19:00 Fairly high during evening twilight at ~18:50 1-

58P/Jackson-Neujmin: A morning comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Orion at magnitude 10.6. Look for a 4' coma. It should fade by about 0.7 magnitudes by month's end.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Very low in the eastern sky during morning twilight at ~02:10 Low in the eastern sky during morning twilight at ~02:30 Low in the eastern sky during morning twilight at ~02:30 Low in the eastern sky during morning twilight at ~02:40 Fairly high in the eastern sky during morning twilight at ~03:00 1-
40o N Low in the eastern sky during morning twilight at ~03:20 Fairly high in the eastern sky during morning twilight at ~03:40 Fairly high in the eastern sky during morning twilight at ~03:40 Fairly high in the eastern sky during morning twilight at ~03:40 Fairly high at ~03:50 1-
Equator Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~05:00 Fairly high in moonlight at ~04:50 High at ~04:50 High at ~04:40 1-
30o S Fairly high during morning twilight at ~05:40 Fairly high during morning twilight at ~05:30 Fairly high in the eastern sky at ~05:10 Fairly high at ~05:00 Fairly high at ~05:00 1-

29P/Schwassmann-Wachmann: A morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Aries at magnitude 12.7. Look for a 40" coma. It should brighten slowly.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Fairly high during morning twilight at ~02:10 High during morning twilight at ~02:10 High during morning twilight at ~01:50 High at ~02:10 High at ~02:30 1-
40o N High during morning twilight at ~03:20 High during morning twilight at ~03:30 High in moonlight at ~03:20 High at ~03:30 High at ~03:40 1-
Equator High during morning twilight at ~04:50 High during morning twilight at ~04:50 High in moonlight at ~04:40 High at ~04:30 High at ~04:20 1-
30o S Fairly high during morning twilight at ~05:30 Fairly high during morning twilight at ~05:20 Fairly high at ~04:30 Fairly high at ~04:40 Fairly high at ~04:40 1-

C/2019 N1 (ATLAS): An evening comet visible in very large telescopes
This comet begins the month in Canes Venatici at magnitude 12.7. Look for a 2.5' coma. It should brighten slowly, moving into Coma Berenices by month's end.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Fairly high in the western sky during evening twilight at ~22:10 Fairly high in the western sky during evening twilight at ~21:50 Low in the western sky during evening twilight at ~22:00 Low in the western sky during evening twilight at ~21:30 Low in the western sky during evening twilight at ~20:40 1-
40o N Fairly high during evening twilight at ~20:40 Fairly high in the western sky during evening twilight at ~20:50 Fairly high in the western sky during evening twilight at ~20:30 Low in the western sky during evening twilight at ~20:20 Low in the western sky during evening twilight at ~19:50 1-
Equator Fairly high in the northern sky during evening twilight at ~19:10 Fairly high in the western sky during evening twilight at ~19:20 Low in the western sky during evening twilight at ~19:20 Low in the western sky during evening twilight at ~19:10 Low in the western sky during evening twilight at ~19:00 1-
30o S Very low in the northern sky during evening twilight at ~18:20 Very low in the northern sky during evening twilight at ~18:40 Very low in the western sky during evening twilight at ~18:40 Very low in the western sky during evening twilight at ~18:40 Not visible 1-26

246P/NEAT: An evening comet visible in very large telescopes
This comet begins the month in Virgo at magnitude 14.1. Look for a 45" coma. It should remain constant.  FINDER CHART
Latitude Visibility August 1 Visibility August 8 Visibility August 15 Visibility August 22 Visibility August 29 Nights Visible
55o N Low in the western sky during evening twilight at ~21:40 Very low in the western sky during evening twilight at ~21:30 Very low in the western sky during evening twilight at ~21:10 Very low in the western sky during evening twilight at ~20:40 Very low in the western sky during evening twilight at ~20:10 1-27, 29-29
40o N Fairly high in the western sky during evening twilight at ~20:30 Low in the western sky during evening twilight at ~20:40 Low in the western sky during evening twilight at ~20:30 Low in the western sky during evening twilight at ~20:10 Low in the western sky during evening twilight at ~19:40 1-
Equator High during evening twilight at ~19:10 High at ~19:20 Fairly high at ~19:20 Fairly high during evening twilight at ~19:10 Fairly high during evening twilight at ~19:00 1-
30o S High during evening twilight at ~18:40 Fairly high at ~19:00 Fairly high at ~19:00 Fairly high during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~18:50 1-

Summary Data for This Month's Telescopic Comets


Comets brighter than 15th 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/2020 F3 (NEOWISE) Coma Berenices 5.4 4.7' 7.7 3.2' 9.7 2.2' 2020 July 29
C/2019 U6 (Lemmon) Coma Berenices 9.2 2.0' 10.2 1.7' 11.2 1.4' 2020 July 30
2P/Encke Corvus 9.5 1.1' 11.4 55" 13.3 40" 2020 July 28
88P/Howell Virgo 10.0 3.5' 9.8 3.4' 9.6 3.3' 2020 July 25
C/2017 T2 (PANSTARRS) Coma Berenices 10.1 1.0' 10.5 55" 11.0 49" 2020 July 30
58P/Jackson-Neujmin Orion 10.6 4.0' 10.9 4.0' 11.3 4.1' 2020 July 25
C/2019 N1 (ATLAS) Canes Venatici 11.6 2.5' 11.4 2.5' 11.2 2.5' 2020 July 25
29P/Schwassmann-Wachmann Aries 12.7 38" 12.6 40" 12.5 42" 2020 August 1
C/2019 Y1 (ATLAS) Virgo 13.9 40" 14.4 36" 15.0 32" 2020 July 13
246P/NEAT Virgo 14.1 47" 14.1 46" 14.2 44" 2020 July 10
C/2018 N2 (ASASSN) Camelopardalis 14.4 38" 14.5 38" 14.7 37" 2020 July 13
C/2017 K2 (PANSTARRS) Draco 14.9 48" 14.8 49" 14.8 49" 2020 July 12
115P/Maury Aquila 15.2 19" 15.4 18" 15.6 17" 2020 July 13
C/2020 F8 (SWAN) Gemini 15.7 2.1' 16.3 2.0' 16.9 2.0' 2020 June 2
C/2019 K7 (Smith) Sagitta 15.7 48" 15.8 46" 15.9 44" 2020 July 28
C/2020 F5 (MASTER) Apus 15.8 8" 15.7 8" 15.7 8" 2020 July 9
C/2019 L3 (ATLAS) Cassiopeia 16.3 51" 16.1 53" 16.0 56" 2020 July 22
*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

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