Comet Chasing in April


Comet chasing is the visual observation of telescopic comets.

News


  • C/2016 R2 (PANSTARRS) will reach perihelion in early May. 

  • C/2016 N6 (PANSTARRS) will reach perihelion in mid July. It is predicted to reach maximum brightness of magnitude 12.3 in late June.

  • C/2016 M1 (PANSTARRS) will reach perihelion in early August. It is predicted to reach maximum brightness of magnitude 8 in late July.

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

  • C/2017 O1 (ASASSN) was a new discovery on July 19 by the All-Sky Automated Survey for Supernovae (ASASSN) program. This program is designed to discover supernovae. This is its first comet discovery. It passed perihelion in mid October, at which time the comet passed within 0.7 AU of the earth. 

  • 62P/Tsuchinshan was recovered in August. It had not been seen since 2004. It brightened significantly and passed perihelion in late November. It has recently been too close to the sun to be observed.

  • 29P/Schwassmann-Wachmann was very active in late August and September. It had the second of two outbursts that occurred within a few days of one another. This second outburst was the brightest since 2010, brightening it up to 12th magnitude. On July 2 in had an outburst that for the first time was caught as the outburst occurred (see https://www.britastro.org/node/10684). Primary outbursts, resulting in a brightening of 0.5 - 1.0 magnitudes, occur roughly every 59 days, typically taking 5-10 days to subside. But up to three subsequent outbursts, such as the one ones recently, may occur 5-10 days afterward, each typically smaller than the last, but sometimes they can be even brighter than the first.  

Read about the first interstellar object to pass through our solar system

 

 

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 April


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

C/2016 M1 (PANSTARRS): A morning comet visible in small telescopes
This comet begins the month in Aquila at magnitude 11.4. Look for a 2' coma. It should brighten by about 0.9 magnitudes by month's end.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N Fairly high in the eastern sky during morning twilight at ~04:00 Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~02:50 Low in the eastern sky during morning twilight at ~02:30 Low in the southern sky during morning twilight at ~02:40 1-
40o N Fairly high during morning twilight at ~04:30 Fairly high during morning twilight at ~04:10 Fairly high during morning twilight at ~03:50 Fairly high during morning twilight at ~03:30 Fairly high during morning twilight at ~03:40 1-
Equator High during morning twilight at ~05:00 High during morning twilight at ~04:50 High at ~04:40 High at ~04:40 High in moonlight at ~04:00 1-
30o S High during morning twilight at ~05:00 High during morning twilight at ~05:00 High at ~04:50 High at ~04:50 High in moonlight at ~04:10 1-

C/2016 R2 (PANSTARRS): An evening comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Perseus at magnitude 11.3. Look for a 2.5' coma. It should fade slowly, moving into Auriga by month's end.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N High during evening twilight at ~20:20 Fairly high at ~21:10 Fairly high during evening twilight at ~21:30 Fairly high in the western sky during evening twilight at ~21:40 Fairly high in the western sky during evening twilight at ~21:30 1-
40o N High during evening twilight at ~19:40 Fairly high at ~20:10 Fairly high at ~20:20 Fairly high during evening twilight at ~20:20 Fairly high during evening twilight at ~20:10 1-
Equator Fairly high during evening twilight at ~19:00 Fairly high in the western sky at ~19:20 Fairly high in the western sky at ~19:10 Fairly high in the northern sky during evening twilight at ~19:10 Low in the northern sky during evening twilight at ~19:00 1-
30o S Low in the northern sky during evening twilight at ~18:50 Very low in the northern sky during evening twilight at ~18:50 Very low in the northern sky during evening twilight at ~18:40 Not visible Not visible 1-23

C/2016 N6 (PANSTARRS): A northern hemisphere evening comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Camelopardus at magnitude 12.0. Look for a 1' coma. It should remain constant, moving into Lynx by month's end.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N High in moonlight at ~22:10 High at ~21:30 High at ~21:40 Fairly high at ~01:30 High during evening twilight at ~21:50 1-
40o N High in moonlight at ~21:40 High at ~20:20 High at ~20:30 Fairly high at ~00:40 High during evening twilight at ~20:20 1-
Equator Low in the northern sky in moonlight at ~20:30 Low in the northern sky at ~19:30 Fairly high in the northern sky at ~19:20 Fairly high in the northern sky during evening twilight at ~19:10 Fairly high in the northern sky during evening twilight at ~19:00 1-
30o S Not visible Not visible Not visible Not visible Not visible  

66P/du Toit: A morning comet visible in a 12.5-inch (32 cm) telescope
This comet begins the month in Corona Australis at magnitude 12.8. Look for a 3' coma. It should brighten by about 0.7 magnitudes, moving into Grus by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Very low in the southern sky during morning twilight at ~04:40 Very low in the southern sky during morning twilight at ~04:30 Not visible Not visible Not visible 1-14
Equator High during morning twilight at ~05:00 High during morning twilight at ~04:50 High at ~04:40 Fairly high at ~04:40 High during morning twilight at ~04:50 1-
30o S High during morning twilight at ~04:50 High during morning twilight at ~05:00 High at ~04:50 High at ~04:50 High during morning twilight at ~05:10 1-

C/2015 O1 (PANSTARRS): A morning comet visible in a 16-inch (41 cm) telescope
This comet begins the month in Bootes at magnitude 13.5. Look for a 1' coma. It should fade slowly, moving into Ursa Major by month's end.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N High in moonlight at ~02:40 High at ~02:10 High at ~01:20 High at ~01:30 High in moonlight at ~23:30 1-
40o N High in moonlight at ~02:40 High at ~01:10 High at ~01:20 High at ~00:40 High in moonlight at ~23:30 1-
Equator Fairly high in moonlight at ~02:50 Fairly high at ~00:00 Fairly high at ~01:20 Fairly high at ~00:30 Fairly high in moonlight at ~23:40 1-
30o S Very low in the northern sky in moonlight at ~03:00 Very low in the northern sky in moonlight at ~02:10 Very low in the northern sky at ~01:20 Very low in the northern sky at ~00:30 Not visible 1-23

C/2017 T3 (ATLAS): A far-northern evening comet visible in very large telescopes
This comet begins the month in Triangulum at magnitude 14.7. Look for a 30" coma. It should brighten by about 1.1 magnitudes, moving into Aries by month's end.  FINDER CHART
Latitude Visibility March 31 Visibility April 7 Visibility April 14 Visibility April 21 Visibility April 28 Nights Visible
55o N Low in the western sky during evening twilight at ~20:10 Low in the western sky during evening twilight at ~20:50 Very low in the northern sky during evening twilight at ~21:00 Very low in the northern sky during evening twilight at ~21:00 Not visible 1-22
40o N Low in the western sky during evening twilight at ~19:30 Very low in the western sky during evening twilight at ~19:50 Very low in the western sky during evening twilight at ~19:50 Not visible Not visible 1-19
Equator Not visible Not visible Not visible Not visible Not visible  
30o S Not visible Not visible Not visible Not visible Not visible  

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

April 1st

April 15th

April 30th

Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2016 R2 (PANSTARRS) Perseus 11.3 2.4' 11.3 2.3' 11.4 2.2' 2018 March 21
C/2016 M1 (PANSTARRS) Aquila 11.4 1.4' 11.0 1.6' 10.5 1.8' 2018 March 27
C/2016 N6 (PANSTARRS) Camelopardalis 12.0 1.2' 12.0 1.2' 12.0 1.1' 2018 March 21
66P/du Toit Corona Australis 12.8 2.6' 12.4 2.8' 12.1 3.0' 2018 March 28
C/2015 O1 (PANSTARRS) Bootes 13.5 1.2' 13.5 1.2' 13.6 1.2' 2018 March 25
62P/Tsuchinshan Virgo 14.2 2.1' 14.8 2.0' 15.6 1.8' 2018 February 11
C/2015 V2 (Johnson) Phoenix 14.7? 1.4'? 14.9? 1.4'? 15.0? 1.4'? 2018 January 16
C/2017 T3 (ATLAS) Triangulum 14.7 31" 14.2 32" 13.6 33" 2018 February 18
C/2017 K6 (Jacques) Taurus 14.8 1.2' 15.1 1.1' 15.5 60" 2018 February 10
C/2017 M4 (ATLAS) Cygnus 15.3 19" 15.1 20" 14.9 21" 2018 March 13

*In solar conjunction and generally not visible

For information about specific comets see Gary W. Kronk's Cometography 

Join the Comet Chasing discussion group 

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