Comet Chasing in March

Comet chasing is the visual observation of telescopic comets.

News

  • C/2018 Y1 (Iwamoto) passed perihelion in early February. 

  • 46P/Wirtanen passed perihelion in mid-December, when it also passed within 0.1 AU of the earth. It should continue to fade rapidly.

  • 78P/Gehrels will reach perihelion in early April, when it is currently predicted to reach maximum brightness of magnitude 11.5 in mid March.

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

  • 123P/West-Hartley will reach perihelion in early February.

  • C/2018 N2 (ASASSN) will reach perihelion in mid November 2019. It is currently predicted to reach maximum brightness of magnitude 11.2 in late October.

  • 38P/Stephan-Oterma passed perihelion in early November. 

  • C/2018 L2 (ATLAS) passed perihelion in early December. It should fade slowly.

  • 64P/Swift-Gehrels passed perihelion in early November, when it passed within 0.4 AU of the earth.

  • 21P/Giacobini-Zinner passed perihelion in early September. Also in early September this comet passed within 0.4 AU of the earth.

  • 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. 

  • C/2016 M1 (PANSTARRS) passed perihelion in early August. Maximum brightness of magnitude 8 occurred in late July. 

  • C/2017 S3 (PANSTARRS) disintegrated during perihelion passage.

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 March

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

C/2018 Y1 (Iwamoto): An evening comet visible in binoculars
This comet begins the month in Auriga at magnitude 7.3. Look for a 11.5' coma. It should fade rapidly, moving into Perseus by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N High at ~19:50 High at ~20:00 High during evening twilight at ~19:50 High at ~20:30 Fairly high at ~20:50 1-
40o N High at ~19:40 High in moonlight at ~19:40 High during evening twilight at ~19:30 High at ~19:50 High at ~20:00 1-
Equator High at ~19:30 High in moonlight at ~19:30 High during evening twilight at ~19:10 Fairly high at ~19:20 Fairly high at ~19:20 1-
30o S Fairly high in the northern sky at ~20:00 Low in the northern sky during evening twilight at ~19:40 Low in the northern sky during evening twilight at ~19:20 Low in the northern sky during evening twilight at ~19:20 Low in the northern sky during evening twilight at ~19:10 1-

46P/Wirtanen: An evening comet visible in small telescopes
This comet begins the month in Ursa Major at magnitude 9.5. Look for a 7.5' coma. It should fade rapidly, moving into Leo Minor by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N High at ~23:00 High at ~22:40 Fairly high in the western sky during morning twilight at ~04:50 High at ~21:40 High at ~21:30 1-
40o N High at ~23:00 High at ~22:40 Fairly high in the western sky at ~03:50 High at ~21:20 High at ~21:30 1-
Equator High at ~23:00 High at ~22:40 Low in the western sky at ~02:30 High at ~20:40 High at ~21:30 1-
30o S Low in the northern sky at ~23:00 Low in the northern sky at ~22:40 Low in the northern sky in moonlight at ~22:10 Low in the northern sky at ~20:10 Fairly high in the northern sky at ~21:30 1-

C/2016 M1 (PANSTARRS): A southern hemisphere evening comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Reticulum at magnitude 11.7. Look for a 2.5' coma. It should fade slowly, moving into Dorado by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 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 the southern sky at ~19:30 Fairly high in the southern sky in moonlight at ~19:20 Fairly high in the southern sky during evening twilight at ~19:10 Fairly high in the southern sky during evening twilight at ~19:20 Fairly high in the southern sky during evening twilight at ~19:20 1-
30o S High at ~20:00 High at ~19:50 High during evening twilight at ~19:30 High at ~19:30 High at ~19:20 1-

38P/Stephan-Oterma: An evening comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Lynx at magnitude 11.8. Look for a 2' coma. It should fade rapidly.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N High at ~21:50 High at ~21:30 Fairly high in the northern sky during morning twilight at ~04:50 High at ~21:00 High at ~21:00 1-
40o N High at ~21:50 High at ~21:30 Low in the western sky at ~03:50 High at ~20:40 High at ~20:30 1-
Equator High at ~21:50 High at ~21:30 High in moonlight at ~21:00 High at ~20:40 High at ~20:20 1-
30o S Low in the northern sky at ~21:50 Low in the northern sky at ~21:30 Low in the northern sky in moonlight at ~21:00 Low in the northern sky at ~20:10 Low in the northern sky at ~20:20 1-

123P/West-Hartley: A morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Ursa Major at magnitude 12.4. Look for a 1' coma. It should fade slowly, moving into Leo Minor by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N High at ~00:40 High at ~00:10 Fairly high during morning twilight at ~04:50 High at ~21:40 High at ~22:30 1-
40o N High at ~00:40 High at ~00:10 Fairly high at ~03:50 High at ~21:20 High at ~22:30 1-
Equator High at ~00:40 High at ~00:10 Fairly high at ~02:30 High at ~20:40 High at ~22:30 1-
30o S Fairly high in the northern sky at ~00:40 Fairly high in the northern sky at ~00:10 Fairly high in the northern sky at ~01:40 Low in the northern sky at ~20:10 Fairly high at ~22:30 1-

64P/Swift-Gehrels: An evening comet visible in a 10-inch (25 cm) telescope
This comet begins the month in Taurus at magnitude 11.0. Look for a 4' coma. It should fade rapidly, moving into Gemini by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N High at ~19:50 High at ~20:00 High during evening twilight at ~19:50 High at ~20:30 High at ~20:50 1-
40o N High at ~19:40 High in moonlight at ~19:40 High during evening twilight at ~19:30 High at ~20:00 High at ~20:00 1-
Equator High at ~19:30 High in moonlight at ~19:30 High during evening twilight at ~19:10 High at ~19:30 High at ~19:20 1-
30o S Fairly high at ~20:00 Fairly high at ~19:50 Fairly high during evening twilight at ~19:20 Fairly high at ~19:30 Fairly high at ~19:20 1-

C/2017 M4 (ATLAS): A morning comet visible in a 12.5-inch (32 cm) telescope
This comet begins the month in Ophiuchus at magnitude 13.1. Look for a 60" coma. It should brighten slowly. The best visibility is mid-month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Very low in the southern sky during morning twilight at ~05:00 Very low in the southern sky during morning twilight at ~04:40 Very low in the southern sky during morning twilight at ~04:40 Very low in the southern sky during morning twilight at ~04:30 Very low in the southern sky during morning twilight at ~03:50 1-
40o N Fairly high in the southern sky at ~05:00 Fairly high in the southern sky at ~04:50 Fairly high in the southern sky at ~04:40 Fairly high in the southern sky during morning twilight at ~04:40 Low in the southern sky at ~03:40 1-
Equator High in moonlight at ~04:50 High at ~04:50 High at ~04:50 High during morning twilight at ~05:00 High at ~02:30 1-
30o S High in moonlight at ~04:30 High at ~04:30 High at ~04:30 High during morning twilight at ~04:50 High in moonlight at ~04:40 1-

C/2016 N6 (PANSTARRS): An evening comet visible in an 18-inch (46 cm) telescope
This comet begins the month in Lepus at magnitude 13.5. Look for a 1' coma. It should fade by about 0.6 magnitudes by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Low in the southern sky during evening twilight at ~19:40 Low in the southern sky during evening twilight at ~19:40 Low in the southern sky during evening twilight at ~19:40 Very low in the southern sky during evening twilight at ~20:00 Very low in the southern sky during evening twilight at ~20:00 1-
40o N Fairly high in the southern sky at ~19:30 Fairly high in the southern sky in moonlight at ~19:30 Fairly high in the southern sky during evening twilight at ~19:20 Fairly high in the southern sky during evening twilight at ~19:40 Low in the southern sky during evening twilight at ~19:50 1-
Equator High at ~19:40 High in moonlight at ~19:30 High during evening twilight at ~19:20 High at ~19:20 High at ~19:20 1-
30o S High at ~20:00 High at ~20:20 High during evening twilight at ~19:30 High at ~19:30 High at ~19:20 1-

C/2018 L2 (ATLAS): A far-northern morning comet visible in very large telescopes
This comet begins the month in Lacerta at magnitude 11.7. Look for a 7.5' coma. It should fade by about 0.7 magnitudes, moving into Andromeda by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Fairly high in the eastern sky at ~04:40 Fairly high in the eastern sky at ~04:30 Fairly high in the eastern sky during morning twilight at ~04:50 Low in the northern sky during evening twilight at ~20:20 Fairly high in the northern sky at ~03:20 1-
40o N Low in the eastern sky 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 Low in the eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight at ~04:20 1-
Equator Not visible Not visible Not visible Not visible Not visible  
30o S Not visible Not visible Not visible Not visible Not visible  

60P/Tsuchinshan: A morning comet visible in very large telescopes
This comet begins the month in Virgo at magnitude 13.8. Look for a 1' coma. It should fade by about 0.8 magnitudes, moving into Leo by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Fairly high in the southern sky at ~01:00 Fairly high in the southern sky at ~00:30 Fairly high in the southern sky in moonlight at ~23:40 Fairly high in the southern sky at ~21:40 Fairly high at ~22:50 1-
40o N High at ~01:00 High at ~00:30 Low in the western sky at ~03:50 Fairly high at ~21:20 High at ~22:50 1-
Equator High at ~01:00 High at ~00:30 High at ~02:30 High at ~20:40 High at ~22:50 1-
30o S High at ~01:00 High at ~00:30 High at ~01:40 Fairly high at ~20:10 High at ~22:50 1-

C/2018 N2 (ASASSN): An evening comet visible in very large telescopes
This comet begins the month in Cetus at magnitude 13.9. Look for a 1' coma. It should brighten slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Very low in the western sky during evening twilight at ~19:00 Not visible Not visible Not visible Not visible 1-4
Equator Low 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 ~19:00 Very low in the western sky during evening twilight at ~19:00 Not visible 1-24
30o S Low in the western sky during evening twilight at ~19:50 Low in the western sky during evening twilight at ~19:40 Low in the western sky during evening twilight at ~19:20 Very low in the western sky during evening twilight at ~19:20 Very low in the western sky during evening twilight at ~19:00 1-

78P/Gehrels: An evening comet visible in very large telescopes
This comet begins the month in Pisces at magnitude 13.9. Look for a 2.5' coma. It should remain constant, moving into Aries by month's end.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 Nights Visible
55o N Low in the western sky during evening twilight at ~19:30 Very low in the western sky during evening twilight at ~19:40 Very low in the western sky during evening twilight at ~19:30 Very low in the western sky during evening twilight at ~19:50 Not visible 1-28
40o N Low 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 ~19:20 Very low in the western sky during evening twilight at ~19:30 Very low in the western sky during evening twilight at ~19:30 1-
Equator Low 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 ~19:00 Very low in the western sky during evening twilight at ~19:10 Very low in the western sky during evening twilight at ~19:00 1-
30o S Very low in the western sky during evening twilight at ~19:30 Not visible Not visible Not visible Not visible 1-4, 6-8

C/2018 A6 (Gibbs): A southern hemisphere evening comet visible in very large telescopes
This comet begins the month in Carina at magnitude 14.4. Look for a 35" coma. It should brighten slowly. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 2 Visibility March 9 Visibility March 16 Visibility March 23 Visibility March 30 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 at ~22:50 Fairly high in the southern sky at ~22:00 Fairly high in the southern sky in moonlight at ~21:00 Fairly high at ~20:30 Fairly high at ~19:40 1-
30o S High at ~22:50 High at ~22:00 Fairly high at ~01:40 High at ~20:10 High at ~19:40 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

March 1st

March 15th

March 31st

 Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2018 Y1 (Iwamoto) Auriga 7.3 12.1' 8.7 7.1' 9.8 4.9' 2019 February 25
46P/Wirtanen Ursa Major 9.5 7.4' 10.5 5.8' 11.6 4.5' 2019 February 25
29P/Schwassmann-Wachmann* Pisces 10.1 6.7' 10.1 6.7' 10.1 6.7' 2019 January 26
64P/Swift-Gehrels Taurus 11.0 3.8' 12.0 3.3' 13.1 2.8' 2019 February 25
C/2018 L2 (ATLAS) Lacerta 11.7 7.3' 12.0 6.9' 12.4 6.5' 2019 January 26
C/2016 M1 (PANSTARRS) Reticulum 11.7 2.5' 12.0 2.4' 12.2 2.3' 2019 February 12
38P/Stephan-Oterma Lynx 11.8 1.9' 12.8 1.7' 13.8 1.4' 2019 February 25
123P/West-Hartley Ursa Major 12.4 1.2' 12.5 1.2' 12.8 1.1' 2019 February 25
C/2017 M4 (ATLAS) Ophiuchus 13.1 54" 13.0 58" 12.9 1.1' 2019 February 10
C/2016 N6 (PANSTARRS) Lepus 13.5 1.2' 13.8 1.1' 14.1 1.0' 2019 February 5
78P/Gehrels Pisces 13.8 1.2' 13.8 1.2' 13.8 1.1' 2019 February 23
60P/Tsuchinshan Virgo 13.8 1.1' 14.1 1.0' 14.6 55" 2019 February 12
C/2018 N2 (ASASSN) Cetus 13.9 1.0' 13.8 60" 13.7 1.0' 2019 January 22
C/2016 R2 (PANSTARRS) Hercules 14.3 1.0' 14.4 1.0' 14.6 59" 2019 January 24
C/2018 A6 (Gibbs) Carina 14.4 37" 14.3 37" 14.2 37" 2018 December 31
C/2015 O1 (PANSTARRS) Ursa Major 14.7 58" 14.9 55" 15.1 51" 2019 January 31
C/2018 A3 (ATLAS) Camelopardalis 15.0 31" 15.2 28" 15.4 26" 2019 January 21
C/2017 T2 (PANSTARRS) Cetus 15.4 22" 15.3 22" 15.2 21" 2019 January 26
21P/Giacobini-Zinner Canis Major 15.5 2.1' 16.1 1.8' 16.7 1.6' 2019 February 7
*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 comet observing
 

Links

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