Comet Chasing in May


Comet chasing is the visual observation of telescopic comets.

News


  • 29P/Schwassmann-Wachmann was observed to be in outburst on April 24. Several observers have reported that is has brightened to 13th magnitude. Outbursts occur roughly every 50 days. 

  • C/2017 E4 (Lovejoy)  faded significantly as of April 13, and may be in the process of disintegrating.  Observations as of April 21 show a much fainter comet but with a tail. It will likely continue to fade quickly. This comet is the sixth discovery of Terry Lovejoy of Queensland Australia. He discovered it via images he obtained on March 9. It brightened unexpectedly by about a magnitude on around March 25. Perihelion is in late April and it was predicted reach peak brightness of magnitude ~6.5 on April 15, but it faded by at least 2.5 magnitudes instead. There are no visual observations reported since it faded.  

  • C/2015 ER61 (PANSTARRS) had an outburst in early April, brightening by 1 - 2 magnitudes. It will reach perihelion in early May. With the outburst subsiding it may now be near maximum brightness (as of April 11), but its activity may increase again as it approaches perihelion, so this is one to keep an eye on.

  • C/2017 E1 (Borosov)  was discovered by Gennadii Vladimirovich Borisov of Nauchnij, Crimea, on images taken on March 5. It will pass perihelion in early April and will reach peak brightness of magnitude ~9 on April 5.

  • 73P/Schwassmann-Wachmann split in two on February 10. The new component became larger and substantially brighter, forming a comet pair. It has since faded and is now the fainter of the two. The pair passed perihelion in mid March when they were at their brightest. More about the split here.

  • 41P/Tuttle-Giacobini-Kresak will next reach perihelion in mid April. In early April this comet will pass within 0.1 AU of the earth. It is currently  predicted to reach maximum brightness of magnitude 5.5 in early April. 

  • 2P/Encke passed perihelion in early March when it also passed within 0.7 AU of the earth. Be aware that it is large and diffuse, which will make it harder to spot than its magnitude alone would suggest.

  • C/2016 VZ187 (PANSTARRS) was discovered in November. It passed perihelion in early March. In early April this comet will pass within 0.5 AU of the earth.

  • C/2015 V2 (Johnson) will reach perihelion in mid June 2017. It is currently predicted to reach a maximum brightness of magnitude ~7.5 in early June.

  • 237P/LINEAR has not been observed since November, to the best of my knowledge. It has been in conjunction with the Sun, but should have been picked up in morning twilight by the end of April. It will rise higher in May and could be as bright as 11th magnitude, but it seems likely that it has faded. 

73P and fragment 73P-BT (lower right) on February 13. You can read an article about this image stack, and a movie made from the same set of images here

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.

Comet Synopses for May


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

C/2015 ER61 (PANSTARRS): A morning comet visible in binoculars
This comet begins the month in Pisces at magnitude 7.4. Look for a 5' coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible 1-
40o N Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~03:20 Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~03:10 Low in the eastern sky during morning twilight at ~03:00 1-
Equator Fairly high at ~04:40 Fairly high at ~04:40 Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~04:40 Fairly high at ~04:40 1-
30o S Fairly high at ~05:00 Fairly high at ~05:10 Fairly high during morning twilight at ~05:30 Fairly high during morning twilight at ~05:20 Fairly high in the eastern sky at ~05:20 1-

41P/Tuttle-Giacobini-Kresak: A morning comet visible in binoculars
This comet begins the month in Hercules at magnitude 7.7. Look for a 11.5' coma. It should fade rapidly.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N High at ~01:20 High during morning twilight at ~01:20 Fairly high during evening twilight at ~22:20 High during morning twilight at ~00:10 High during morning twilight at ~00:00 1-
40o N High at ~03:00 High during morning twilight at ~03:20 Fairly high in the eastern sky at ~21:20 High at ~02:10 High at ~02:00 1-
Equator High at ~03:40 High at ~03:20 High in moonlight at ~03:10 High at ~01:50 High at ~02:10 1-
30o S Low in the northern sky at ~03:40 Fairly high in the northern sky at ~03:20 Fairly high in moonlight at ~03:10 Fairly high at ~01:40 High at ~02:10 1-

C/2015 V2 (Johnson): An evening comet visible in binoculars
This comet begins the month in Hercules at magnitude 9.1. Look for a 5' coma. It should brighten by about 0.7 magnitudes, moving into Bootes by month's end.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N High at ~00:50 High in moonlight at ~00:00 High during evening twilight at ~22:20 High during evening twilight at ~23:50 High during evening twilight at ~23:50 1-
40o N High at ~01:20 High during morning twilight at ~03:20 High at ~21:20 High at ~23:10 High at ~22:30 1-
Equator High at ~01:20 Fairly high at ~03:20 Fairly high in the eastern sky at ~20:10 High at ~23:10 High at ~22:30 1-
30o S Low in the northern sky at ~01:20 Very low in the northern sky at ~03:20 Fairly high in the northern sky in moonlight at ~00:00 Fairly high in the northern sky at ~23:10 Fairly high at ~22:30 1-

237P/LINEAR: A morning comet that may be visible in small telescopes
This comet has been in conjunction with the Sun, and has not been observed since November of last year. Based on observations at that time it may be as bright as magnitude 11 as the month opens, but it is likely significantly fainter. It begins the month in Pegasus and should remain more or less constant, moving into Pisces by month's end.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Very low in the eastern sky during morning twilight at ~03:00 Very low in the eastern sky during morning twilight at ~02:40 Very low in the eastern sky during morning twilight at ~02:20 Very low in the eastern sky during morning twilight at ~01:50 Very low in the eastern sky during morning twilight at ~01:40 1-
40o N Low in the eastern sky during morning twilight at ~03:40 Low in the eastern sky during morning twilight at ~03:20 Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~03:10 Fairly high in the eastern sky during morning twilight at ~02:50 1-
Equator Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:40 Fairly high during morning twilight at ~04:50 Fairly high during morning twilight at ~04:40 High at ~04:40 1-
30o S Fairly high in the eastern sky during morning twilight at ~05:10 Fairly high in the eastern sky during morning twilight at ~05:10 Fairly high in the eastern sky during morning twilight at ~05:30 Fairly high during morning twilight at ~05:20 Fairly high during morning twilight at ~05:20 1-

71P/Clark: An evening comet visible in small telescopes
This comet begins the month in Ophiuchus at magnitude 11.9. Look for a 1.5' coma. It should brighten by about 0.7 magnitudes, moving into Scorpius by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Low in the southern sky during morning twilight at ~01:40 Low in the southern sky during morning twilight at ~01:30 Low in the southern sky during morning twilight at ~01:10 Low in the southern sky during morning twilight at ~00:30 Very low in the southern sky during morning twilight at ~00:10 1-
40o N Fairly high at ~02:10 Fairly high in the southern sky during morning twilight at ~03:20 Fairly high in the southern sky in moonlight at ~01:10 Fairly high in the southern sky at ~00:50 Fairly high in the southern sky at ~00:20 1-
Equator High at ~02:10 High at ~03:20 Low in the eastern sky at ~20:10 High at ~00:50 High at ~00:20 1-
30o S High at ~02:10 High at ~03:20 Low in the eastern sky at ~19:30 High at ~00:50 High at ~00:20 1-

29P/Schwassmann-Wachmann: A morning comet visible in an 8-inch (20 cm) telescope
This comet begins the month in Capricornus at magnitude 13.1. It had a 2-magnitude outburst on April 24 and will likely fade back to 15th magnitude, so get it early in the month. FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Not visible Not visible Not visible Very low in the eastern sky during morning twilight at ~02:10 Very low in the eastern sky during morning twilight at ~01:50 1-
40o N Low in the eastern sky during morning twilight at ~03:40 Low in the eastern sky during morning twilight at ~03:20 Fairly high in the southern sky during morning twilight at ~03:30 Fairly high in the southern sky during morning twilight at ~03:00 Fairly high in the southern sky during morning twilight at ~02:50 1-
Equator High at ~04:40 High at ~04:40 High during morning twilight at ~04:50 High in moonlight at ~04:40 High at ~04:30 1-
30o S High at ~05:10 High at ~05:10 High during morning twilight at ~05:20 High in moonlight at ~05:10 High at ~05:10 1-

C/2017 E1 (Borisov): A morning comet visible in a 12.5-inch (32 cm) telescope
This comet begins the month in Pisces at magnitude 11.1. Look for a 1.5' coma. It should fade by about 1.5 magnitudes by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Very low in the eastern sky during morning twilight at ~04:10 Not visible Not visible Not visible Not visible 1-1, 5-5
Equator Low in the eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight 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 1-
30o S Low in the eastern sky during morning twilight at ~05:10 Low in the eastern sky during morning twilight at ~05:10 Fairly high in the eastern sky during morning twilight at ~05:30 Fairly high in the eastern sky during morning twilight at ~05:20 Fairly high in the eastern sky during morning twilight at ~05:20 1-

73P/Schwassmann-Wachman): A southern hemisphere morning comet visible in a 12.5-inch (32 cm) telescope
This comet split in February and is now a pair of comets. The new, brighter and larger, coma was designated as 73P-BT. Recent reports now put it fainter than the main component. These comets begins the month in Cetus at magnitude 11.5/13.4. Look for a 1.5'/1' comas. They should fade by about 1.4 magnitudes by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 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 eastern sky during morning twilight at ~04:50 Low in the eastern sky during morning twilight at ~04:40 Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:40 Fairly high in the eastern sky during morning twilight at ~04:40 1-
30o S Fairly high in the eastern sky at ~05:10 Fairly high in the eastern sky at ~05:10 Fairly high during morning twilight at ~05:30 Fairly high in the eastern sky during morning twilight at ~05:20 Fairly high at ~05:20 1-

C/2017 E4 (Lovejoy): A far-northern morning comet visible in very large telescopes
This comet faded significantly prior to passing perihelion and begins the month in Triangulum at magnitude 10.0. Look for a 2.5' coma. It should fade rapidly, moving into Taurus by month's end.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Very low in the northern sky during morning twilight at ~02:20 Very low in the northern sky during morning twilight at ~02:30 Not visible Not visible Not visible 1-9
40o N Very low in the eastern sky during morning twilight at ~03:50 Very low in the eastern sky during morning twilight at ~04:00 Not visible Not visible Not visible 1-8
Equator Not visible Not visible Not visible Not visible Not visible  
30o S Not visible Not visible Not visible Not visible Not visible  

2P/Encke: A morning comet visible in very large telescopes
This comet begins the month in Aquarius at magnitude 12.1. Look for a 2' coma. It should fade rapidly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 29 Visibility May 6 Visibility May 13 Visibility May 20 Visibility May 27 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Very low in the eastern sky during morning twilight at ~03:50 Very low in the eastern sky during morning twilight at ~03:40 Low in the eastern sky during morning twilight at ~03:40 Low in the eastern sky during morning twilight at ~03:10 Low in the eastern sky during morning twilight at ~03:00 1-
Equator Fairly high at ~04:40 Fairly high at ~04:40 High during morning twilight at ~04:50 High in moonlight at ~04:40 High at ~04:30 1-
30o S High at ~05:00 High at ~05:00 High during morning twilight at ~05:20 High in moonlight at ~05:10 High at ~05:10 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

May 1st

May 15th

May 31st

Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2015 ER61 (PANSTARRS) Pisces 7.4 5.0' 7.5 4.8' 7.8 4.4' 2017 April 28
41P/Tuttle-Giacobini-Kresak Hercules 7.7 11.5' 9.1 9.5' 10.9 7.7' 2017 April 28
C/2015 V2 (Johnson) Hercules 9.1 4.2' 8.7 4.7' 8.4 5.2' 2017 April 28
C/2017 E4 (Lovejoy) Triangulum 10.0 2.3' 11.8 1.9' 13.5 1.6' 2017 April 21
237P/LINEAR Pegasus 11? 3'? 11? 3'? 11? 3'? 2016 November 17
C/2017 E1 (Borisov) Pisces 11.1 1.3' 11.8 1.2' 12.6 1.1' 2017 April 29
71P/Clark Ophiuchus 11.9 1.1' 11.5 1.2' 11.1 1.3' 2017 April 28
2P/Encke Aquarius 12.1 2.0' 13.2 2.0' 14.2 2.0' 2017 April 28
29P/Schwassmann-Wachmann Capricornus 13.1 28" 13.0 29" 12.9 31" 2017 April 28
73P/Schwassmann-Wachmann Cetus 13.1 54" 13.8 52" 14.6 50" 2017 April 5
73P-BT/Schwassmann-Wachmann Cetus 13.4 1.1' 14.1 1.1' 14.9 1.0' 2017 April 2
C/2016 R2 (PANSTARRS)* Eridanus 13.7 3.5' 13.6 3.6' 13.4 3.7' 2017 January 14
C/2016 N4 (MASTER) Pegasus 14.6 18" 14.4 19" 14.2 20" 2016 December 29

*In solar conjunction and generally not visible

For the latest news and comet observations see the ICQ/CBAT/MPC: Recent Comet Magnitude Estimates page.  The Astronomical Headlines page of the IAU is also a good source of information, particularly for recent discoveries.

For general information about 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