Comet Chasing in January


Comet chasing is the visual observation of telescopic comets.

News


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

  • C/2018 Y1 (Iwamoto) will reach perihelion in early February. In mid February it will pass within 0.3 AU of the earth, when it is currently predicted to reach maximum brightness of magnitude 7.3.

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

  • 78P/Gehrels will reach perihelion in early April, when it is currently predicted to reach maximum brightness of magnitude 14 in mid March.

  • C/2018 N2 (ASASSN) will reach perihelion in mid-November 2019. It is predicted to reach maximum brightness of magnitude 11 in late October 2019.

  • 38P/Stephan-Oterma passed perihelion in early November. In mid December this comet passed within 0.8 AU of the earth. 

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

  • C/2018 V1 (Machholz-Fujikawa-Iwamoto) is a new rare visual discovery.  See MPEC 2018-V151 for the discovery details.  It passed perihelion in early December. It should fade rapidly in January. 

  • C/2017 S3 (PANSTARRS) has apparently disintegrated during perihelion passage. Juan Jose Gonzalez reported visual sightings of the remnant as recently as November 16, but no other observers have confirmed.    During an outburst in July it brightened by ~3 magnitudes, making it a visually observable object. On July 20 it was a binocular object at magnitude 7.3. 

  • 64P/Swift-Gehrels passed perihelion in early November, when it will also pass 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/2016 R2 (PANSTARRS) passed perihelion in early May. 

  • 48P/Johnson passed perihelion in mid August.

  • C/2015 O1 (PANSTARRS) is past perihelion, which occurred in mid February 2018.

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 January


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

46P/Wirtanen: A morning comet visible in binoculars
This comet begins the month in Lynx at magnitude 4.8. Look for a 38.5' coma. It should fade rapidly, moving into Ursa Major by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N High at ~00:20 High at ~01:00 High at ~01:20 High in moonlight at ~01:00 High at ~23:50 1-
40o N High at ~00:10 High at ~01:00 High at ~01:20 High in moonlight at ~01:10 High at ~23:40 1-
Equator Fairly high at ~00:10 Fairly high at ~01:00 Fairly high at ~01:10 Low in the northern sky during morning twilight at ~05:10 Fairly high at ~23:20 1-
30o S Very low in the northern sky at ~00:10 Not visible Not visible Not visible Very low in the northern sky in moonlight at ~01:00 1-

C/2018 Y1 (Iwamoto): A morning comet visible in binoculars
This comet begins the month in Hydra at magnitude 11.2. Look for a 4.5' coma. It should brighten rapidly, moving into Virgo by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Very low in the southern sky during morning twilight at ~06:30 Low in the southern sky during morning twilight at ~06:10 Low in the southern sky at ~06:00 Low in the southern sky in moonlight at ~05:50 Low in the southern sky in moonlight at ~05:10 1-
40o N Fairly high in the southern sky during morning twilight at ~05:50 Fairly high in the southern sky at ~05:40 Fairly high in the southern sky at ~05:40 Fairly high in the southern sky in moonlight at ~05:30 Fairly high in moonlight at ~05:10 1-
Equator High during morning twilight at ~04:50 High at ~04:40 High at ~04:40 High during morning twilight at ~05:10 High in moonlight at ~05:00 1-
30o S Fairly high during morning twilight at ~03:30 High at ~03:30 High at ~03:30 High during morning twilight at ~04:10 High during morning twilight at ~04:00 1-

38P/Stephan-Oterma: A morning comet visible in small telescopes
This comet begins the month in Lynx at magnitude 10.0. Look for a 4.5' coma. It should fade rapidly.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N High at ~00:50 High at ~01:40 High at ~01:10 High in moonlight at ~00:30 High at ~23:50 1-
40o N High at ~00:40 High at ~01:40 High at ~01:10 High in moonlight at ~00:30 High at ~23:40 1-
Equator High at ~00:40 High at ~01:40 High at ~01:10 Low in the northern sky during morning twilight at ~05:10 High at ~23:20 1-
30o S Low in the northern sky at ~00:30 Low in the northern sky at ~01:40 Low in the northern sky at ~01:10 Low in the northern sky in moonlight at ~00:40 Low in the northern sky at ~23:10 1-

C/2018 L2 (ATLAS): A far-northern morning comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Hercules at magnitude 9.7. Look for a 4.5' coma. It should fade slowly, moving into Vulpecula by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Low in the western sky during evening twilight at ~17:50 Low in the western sky during evening twilight at ~18:00 Low in the eastern sky during morning twilight at ~06:10 Fairly high in the eastern sky during morning twilight at ~06:30 Low in the western sky during evening twilight at ~18:30 1-
40o N Low in the western sky during evening twilight at ~18:10 Low in the western sky during evening twilight at ~18:20 Low in the eastern sky during morning twilight at ~05:50 Low in the eastern sky during morning twilight at ~06:10 Low in the western sky during evening twilight at ~18:30 1-
Equator Not visible Not visible Not visible Not visible Not visible  
30o S Not visible Not visible Not visible Not visible Not visible  

C/2016 M1 (PANSTARRS): A southern hemisphere evening comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Octans at magnitude 10.6. Look for a 4' coma. It should fade slowly, moving into Hydrus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 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 Very low in the southern sky during evening twilight at ~19:10 Very low in the southern sky during evening twilight at ~19:20 Very low in the southern sky during evening twilight at ~19:20 Low in the southern sky at ~19:30 1-
30o S Fairly high in the southern sky at ~20:50 Fairly high at ~20:50 Fairly high at ~23:10 Fairly high in the southern sky during morning twilight at ~04:10 Fairly high at ~20:40 1-

64P/Swift-Gehrels: An evening comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Aries at magnitude 10.8. Look for a 6' coma. It should fade rapidly, moving into Taurus by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N High at ~20:20 High at ~20:10 High at ~23:00 High in moonlight at ~19:40 High at ~19:40 1-
40o N High at ~20:20 High at ~20:10 High at ~23:00 High in moonlight at ~19:40 High at ~19:40 1-
Equator High at ~20:20 High at ~20:10 Fairly high at ~23:10 High in moonlight at ~19:40 High at ~19:50 1-
30o S Fairly high in the northern sky at ~20:50 Fairly high at ~20:50 Fairly high in moonlight at ~20:40 Fairly high during evening twilight at ~20:20 Fairly high at ~20:30 1-

C/2016 N6 (PANSTARRS): A morning comet visible in a 12.5-inch (32 cm) telescope
This comet begins the month in Canis Major at magnitude 13.0. 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 December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Low in the southern sky at ~00:50 Low in the southern sky at ~00:10 Low in the southern sky at ~23:30 Low in the southern sky in moonlight at ~22:40 Low in the southern sky at ~22:00 1-
40o N Fairly high at ~00:40 Fairly high at ~00:10 Fairly high in the southern sky at ~23:30 Fairly high in the southern sky in moonlight at ~22:40 Fairly high in the southern sky at ~22:00 1-
Equator High at ~00:40 High at ~00:10 High at ~23:30 High in moonlight at ~22:40 High at ~22:00 1-
30o S High at ~00:30 High at ~00:10 High at ~23:30 Low in the western sky during morning twilight at ~04:10 High at ~22:00 1-

C/2016 R2 (PANSTARRS): A morning comet visible in a 14-inch (36 cm) telescope
This comet begins the month in Bootes at magnitude 13.3. Look for a 60" coma. It should fade slowly, moving into Hercules by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N High in moonlight at ~06:10 High at ~06:00 High at ~05:50 High in moonlight at ~05:40 Fairly high in the eastern sky at ~23:50 1-
40o N High during morning twilight at ~05:40 High at ~05:40 High at ~05:40 High at ~05:30 High during morning twilight at ~05:40 1-
Equator Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the northern sky during morning twilight at ~04:50 Fairly high in the northern sky at ~04:50 Fairly high during morning twilight at ~05:10 Fairly high during morning twilight at ~05:00 1-
30o S Not visible Not visible Not visible Not visible Very low in the northern sky during morning twilight at ~04:20 18-

C/2015 O1 (PANSTARRS): A morning comet visible in a 14-inch (36 cm) telescope
This comet begins the month in Ursa Major at magnitude 13.4. Look for a 1' coma. It should remain constant.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N High at ~00:50 High at ~04:30 High at ~03:50 High in moonlight at ~02:50 High at ~23:50 1-
40o N High at ~00:40 High at ~04:30 High at ~03:50 High in moonlight at ~02:50 High at ~23:40 1-
Equator High in moonlight at ~04:40 High at ~04:30 High at ~03:50 High during morning twilight at ~05:10 Fairly high in the northern sky at ~23:20 1-
30o S Low in the northern sky during morning twilight at ~03:40 Low in the northern sky during morning twilight at ~03:30 Low in the northern sky at ~03:30 Low in the northern sky during morning twilight at ~04:10 Low in the northern sky in moonlight at ~02:40 1-

C/2017 M4 (ATLAS): A morning comet visible in very large telescopes
This comet begins the month in Ophiuchus at magnitude 13.9. Look for a 1' coma. It should brighten slowly, moving into Serpens Cauda by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Very low in the eastern sky during morning twilight at ~06:30 Very low in the eastern sky during morning twilight at ~06:20 Very low in the eastern sky during morning twilight at ~06:20 Low in the southern sky during morning twilight at ~06:30 Low in the southern sky during morning twilight at ~06:10 1-
40o N Very low in the eastern sky during morning twilight at ~06:00 Low in the eastern sky during morning twilight at ~05:50 Low in the eastern sky during morning twilight at ~05:50 Low in the eastern sky during morning twilight at ~06:00 Low in the eastern sky during morning twilight at ~05:50 1-
Equator Very low in the eastern sky during morning twilight at ~05:00 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 ~05:10 Fairly high in the eastern sky during morning twilight at ~05:00 1-
30o S Not visible Not visible Very low in the eastern sky during morning twilight at ~04:00 Low in the eastern sky during morning twilight at ~04:10 Fairly high in the eastern sky during morning twilight at ~04:10 7-

C/2018 N2 (ASASSN): An evening comet visible in very large telescopes
This comet begins the month in Sculptor at magnitude 13.9. Look for a 1.5' coma. It should remain constant. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Not visible Not visible Very low in the southern sky during evening twilight at ~17:50 Very low in the southern sky during evening twilight at ~17:50 Very low in the southern sky during evening twilight at ~18:10 6-
40o N Low in the southern sky at ~18:40 Low in the southern sky at ~18:30 Low in the southern sky during evening twilight at ~18:30 Low in the southern sky during evening twilight at ~18:20 Low in the southern sky during evening twilight at ~18:40 1-
Equator High at ~19:30 High at ~19:30 High in moonlight at ~19:30 High during evening twilight at ~19:20 High at ~19:30 1-
30o S High at ~20:50 High at ~20:50 High during evening twilight at ~20:40 High during evening twilight at ~20:20 Fairly high at ~20:30 1-

78P/Gehrels: An evening comet visible in very large telescopes
This comet begins the month in Aquarius at magnitude 14.1. Look for a 3' coma. It should brighten slowly, moving into Pisces by month's end.  FINDER CHART
Latitude Visibility December 29 Visibility January 5 Visibility January 12 Visibility January 19 Visibility January 26 Nights Visible
55o N Fairly high in the southern sky at ~18:00 Fairly high in the southern sky at ~18:10 Fairly high in the southern sky during evening twilight at ~18:10 Fairly high in the southern sky during evening twilight at ~18:00 Fairly high in the western sky during evening twilight at ~18:30 1-
40o N Fairly high at ~18:20 Fairly high at ~18:30 Fairly high during evening twilight at ~18:30 Fairly high during evening twilight at ~18:20 Fairly high in the western sky at ~18:50 1-
Equator High at ~19:20 Fairly high at ~19:30 Fairly high during evening twilight at ~19:20 Fairly high during evening twilight at ~19:20 Fairly high in the western sky at ~19:30 1-
30o S Fairly high in the western sky during evening twilight at ~20:40 Fairly high in the western sky during evening twilight at ~20:30 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 ~20:20 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

January 1st

January 15th

January 31st

Observations as of (UT)
Mag Diam Mag Diam Mag Diam
46P/Wirtanen Lynx 4.8 40.0' 6.2 24.5' 7.7 16.0' 2019 January 1
64P/Swift-Gehrels Aries 9.5 11.5' 10.5 9.6' 11.7 7.8' 2018 December 28
C/2018 L2 (ATLAS) Hercules 9.7 4.5' 9.8 4.5' 10.0 4.4' 2018 December 30
38P/Stephan-Oterma Lynx 10.0 4.5' 10.7 4.2' 11.7 3.7' 2018 December 31
C/2016 M1 (PANSTARRS) Octans 10.6 4.0' 10.8 4.0' 11.0 3.9' 2018 December 29
C/2018 Y1 (Iwamoto) Hydra 11.2 1.4' 10.3 2.0' 8.7 4.0' 2018 December 31
C/2018 V1 (Machholz-Fujikawa-Iwamoto) Sagittarius 12.6 1.9' 14.2 1.6' 15.5 1.4' 2018 December 12
C/2016 N6 (PANSTARRS) Canis Major 13.0 1.3' 13.2 1.3' 13.5 1.2' 2018 December 28
78P/Gehrels Aquarius 13.2 1.6' 13.1 1.5' 13.1 1.5' 2018 December 6
60P/Tsuchinshan Leo 13.2 2.5' 13.1 2.8' 13.1 3.0' 2018 December 31
C/2016 R2 (PANSTARRS) Bootes 13.3 60" 13.5 60" 13.6 60" 2018 December 4
C/2015 O1 (PANSTARRS) Ursa Major 13.4 1.1' 13.4 1.1' 13.4 1.1' 2018 December 12
C/2018 N2 (ASASSN) Sculptor 13.9 1.6' 13.9 1.5' 13.8 1.5' 2018 December 28
C/2017 M4 (ATLAS) Ophiuchus 13.9 1.0' 13.8 1.1' 13.7 1.1' 2018 November 14
48P/Johnson Cetus 14.3 52" 14.6 48" 15.0 44" 2018 December 7
21P/Giacobini-Zinner Columba 14.7 53" 15.4 47" 16.2 41" 2018 December 15
29P/Schwassmann-Wachmann Pisces 14.8 59" 14.9 57" 15.0 56" 2018 December 27
C/2017 T2 (PANSTARRS) Eridanus 14.9 32" 14.8 31" 14.7 30" 2018 December 6
*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