Comet Chasing in August


Comet chasing is the visual observation of telescopic comets.

News


This month brings the slimmest pickings for telescopic comets in recent memory.
  • C/2017 T2 (PANSTARRS) will reach perihelion in early May 2020. It is currently predicted to reach naked eye visibility in mid May 2020. 

  • C/2018 W2 (Africano) will reach perihelion in early September. In late September this comet will pass within 0.5 AU of the earth, when it is predicted to reach maximum brightness of magnitude 8.8.

  • 260P/McNaught will reach perihelion in early September. In early October this comet will pass within 0.6 AU of the earth. It is predicted to reach maximum brightness of magnitude ~10.5 in late September

  • C/2018 R3 (Lemmon) passed perihelion in early June. 

  • C/2018 N2 (ASASSN) will reach perihelion in mid November. It is predicted to reach maximum brightness of magnitude 11.5 in late October.

  • C/2018 A6 (Gibbs) will passed perihelion in mid July.

  • 168P/Hergenrother will pass perihelion in early August but has not been recovered. In July it was fainter than 19th magnitude.

  • P/2008 Y12 (SOHO) has not yet been recovered, even though it was predicted to be approximately magnitude 12 in July.

  • C/2019 D1 (Flewelling) passed perihelion in mid May.

  • C/2018 W1 (Catalina) passed perihelion in mid May. It is predicted to reach maximum brightness of magnitude 11.2 in early June.

  • C/2017 M4 (ATLAS) passed perihleion in mid January. It is predicted to reach maximum brightness of magnitude 13 in early May.

  • 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. But 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 will next reach perihelion in early March 2019. But 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. 

Comet Visibility in the Eyepiece

This page uses code developed for SkyTools 3 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/2017 T2 (PANSTARRS): A morning comet visible in binoculars
This comet begins the month in Taurus at magnitude 8.7. Look for a 8.5' coma. It should brighten by about 0.7 magnitudes by month's end.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 Nights Visible
55o N Low in the eastern sky during morning twilight at ~01:40 Low in the eastern sky during morning twilight at ~01:50 Fairly high in the eastern sky during morning twilight at ~02:50 Fairly high during morning twilight at ~03:00 Fairly high at ~02:40 1-
40o N Fairly high in the eastern sky during morning twilight at ~03:20 Fairly high at ~03:20 High during morning twilight at ~03:50 High during morning twilight at ~04:00 High at ~03:50 1-
Equator Fairly high at ~04:50 High at ~04:50 High during morning twilight at ~05:00 High during morning twilight at ~05:00 High at ~04:40 1-
30o S Fairly high in the northern sky at ~05:20 Fairly high in the northern sky at ~05:10 Fairly high during morning twilight at ~05:20 Fairly high during morning twilight at ~05:20 Fairly high at ~04:50 1-

C/2018 W2 (Africano): A morning comet visible in small telescopes
This comet begins the month in Camelopardus at magnitude 11.5. Look for a 3.5' coma. It should brighten by about 1.5 magnitudes by month's end.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 Nights Visible
55o N Fairly high during morning twilight at ~00:50 High during morning twilight at ~01:20 High during morning twilight at ~02:30 Fairly high at ~22:50 High at ~02:30 1-
40o N High at ~03:10 High at ~03:20 High during morning twilight at ~03:40 Fairly high at ~23:50 High at ~03:40 1-
Equator Fairly high in the northern sky at ~04:50 Fairly high in the northern sky at ~04:50 Fairly high in the northern sky during morning twilight at ~05:00 Fairly high in moonlight at ~04:40 Fairly high at ~04:30 1-
30o S Not visible Not visible Not visible Not visible Very low in the northern sky at ~04:40 23-

260P/McNaught: A morning comet visible in small telescopes
This comet begins the month in Pisces at magnitude 11.5. Look for a 2' coma. It should brighten by about 0.7 magnitudes, moving into Aries by month's end.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 Nights Visible
55o N Fairly high in the eastern sky during morning twilight at ~01:20 Fairly high during morning twilight at ~01:40 High during morning twilight at ~02:40 High during morning twilight at ~02:30 High at ~02:30 1-
40o N High at ~03:10 High at ~03:20 High during morning twilight at ~03:40 High in moonlight at ~03:30 High at ~03:30 1-
Equator High at ~04:30 High at ~04:20 High in moonlight at ~04:20 High at ~01:00 High at ~03:40 1-
30o S High at ~04:40 High at ~04:20 High in moonlight at ~04:20 Fairly high at ~01:50 Fairly high at ~03:40 1-

C/2018 N2 (ASASSN): A morning comet visible in small telescopes
This comet begins the month in Aries at magnitude 11.9. Look for a 1.5' coma. It should brighten by about 0.5 magnitudes by month's end.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 Nights Visible
55o N Fairly high in the eastern sky during morning twilight at ~01:30 Fairly high during morning twilight at ~01:40 High during morning twilight at ~02:40 High during morning twilight at ~02:30 High at ~02:30 1-
40o N High at ~03:10 High at ~03:20 High during morning twilight at ~03:50 High in moonlight at ~03:40 High at ~03:30 1-
Equator High at ~04:40 High at ~04:40 High in moonlight at ~04:50 High in moonlight at ~04:30 High at ~03:50 1-
30o S High at ~05:10 High at ~05:00 High in moonlight at ~05:00 Fairly high in the northern sky at ~01:50 Fairly high at ~03:50 1-

C/2018 W1 (Catalina): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Antlia at magnitude 12.5. Look for a 1.5' coma. It should fade by about 0.8 magnitudes, moving into Centaurus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 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 Low in the western sky during evening twilight at ~19:00 Low in the western sky during evening twilight at ~19:10 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 Fairly high in moonlight at ~18:50 Fairly high during evening twilight at ~18:40 Fairly high at ~19:00 Fairly high in the western sky at ~19:00 Fairly high in the western sky at ~19:10 1-

29P/Schwassmann-Wachmann: A morning comet visible in very large telescopes
This comet begins the month in Pisces at magnitude 13.7. Look for a 3.5' coma. It should brighten slowly.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 Nights Visible
55o N Fairly high during morning twilight at ~01:00 High during morning twilight at ~01:30 High during morning twilight at ~02:30 Fairly high at ~22:50 High at ~02:10 1-
40o N High at ~03:00 High at ~03:10 High in moonlight at ~03:30 High at ~23:50 High at ~02:20 1-
Equator High at ~04:10 High at ~03:40 High in moonlight at ~03:20 High at ~01:00 High at ~02:20 1-
30o S High at ~04:10 High at ~03:40 High in moonlight at ~03:20 High at ~01:50 High at ~02:20 1-

C/2017 M4 (ATLAS): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Centaurus at magnitude 13.9. Look for a 3' coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 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 in moonlight at ~19:20 Fairly high during evening twilight at ~19:10 Fairly high in the southern sky at ~19:20 Fairly high in the southern sky during evening twilight at ~19:10 Low in the southern sky during evening twilight at ~19:10 1-
30o S High in moonlight at ~19:00 High during evening twilight at ~18:50 High at ~19:00 High at ~19:10 Fairly high at ~19:10 1-

C/2018 A6 (Gibbs): A southern hemisphere morning comet visible in very large telescopes
This comet begins the month in Carina at magnitude 14.2. Look for a 30" coma. It should remain constant, moving into Volans by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility August 3 Visibility August 10 Visibility August 17 Visibility August 24 Visibility August 31 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 southern sky at ~05:20 Fairly high in the southern sky at ~05:20 Low in the southern sky during evening twilight at ~18:50 Fairly high in the southern sky during morning twilight at ~05:10 Fairly high at ~04:50 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/2017 T2 (PANSTARRS) Taurus 8.7 7.1' 8.3 7.7' 7.9 8.5' 2019 July 30
C/2018 R3 (Lemmon) Cancer 10.1 4.4' 10.5 4.2' 11.0 4.0' 2019 July 6
C/2018 W2 (Africano) Camelopardalis 11.5 2.0' 10.9 2.5' 10.0 3.5' 2019 August 1
260P/McNaught Pisces 11.5 1.4' 11.1 1.6' 10.8 1.8' 2019 July 30
68P/Klemola Ophiuchus 11.8 2.0' 11.7 2.0' 11.7 1.9' 2019 July 30
C/2018 N2 (ASASSN) Aries 11.9 1.3' 11.6 1.4' 11.4 1.5' 2019 July 30
29P/Schwassmann-Wachmann Pisces 12.6 2.9' 12.5 3.1' 12.4 3.2' 2019 July 26
C/2018 W1 (Catalina) Antlia 14.1 35" 14.5 31" 15.0 28" 2019 July 23
C/2016 M1 (PANSTARRS) Canis Major 14.2 1.2' 14.3 1.2' 14.5 1.2' 2019 June 1
C/2018 A6 (Gibbs) Carina 14.2 31" 14.2 31" 14.2 31" 2019 July 20
C/2017 M4 (ATLAS) Centaurus 14.5 48" 14.7 45" 15.0 42" 2019 July 23
C/2017 B3 (LINEAR) Phoenix 14.7 48" 14.8 48" 14.8 48" 2019 June 11
*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