Comet Chasing in April


Comet chasing is the visual observation of telescopic comets.

News


  • C/2017 E4 (Lovejoy)  has faded significantly as of April 13, and may be disintegrating.  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.

  • 29P/Schwassmann-Wachmann is no longer favorable for observation and no observations have been reported since November. It had another of its large outbursts near the beginning of November,  brightening to magnitude 12.8. It faded back to ~15th magnitude afterward. Outbursts occur roughly every 50 days. 

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 April


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

C/2015 ER61 (PANSTARRS): A morning comet visible in binoculars
This comet began the month in Capricornus at magnitude 8.6, but suddenly brightened to 6th magnitude in the first week of April. Look for a 8' coma. As the outburst subsides it should also brighten slowly due to its distance from the sun such that it may remain relatively constant. Additional outbursts may occur. It will move into Aquarius by month's end.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N Very low in the eastern sky during morning twilight at ~04:10 Very low in the eastern sky during morning twilight at ~04:00 Not visible Not visible Not visible 1-
40o N Low in the eastern sky during morning twilight at ~04:20 Low in the eastern sky during morning twilight at ~04:20 Low in the eastern sky during morning twilight at ~04:10 Low in the eastern sky during morning twilight at ~03:40 Low in the eastern sky during morning twilight at ~03:30 1-
Equator High at ~04:50 Fairly high at ~04:50 High during morning twilight at ~05:00 Fairly high in moonlight at ~04:40 Fairly high at ~04:40 1-
30o S High at ~04:50 High at ~04:50 High during morning twilight at ~05:10 Fairly high in moonlight at ~05:00 Fairly high at ~05:00 1-

C/2017 E4 (Lovejoy): A morning comet visible in binoculars?
This comet brightened by about a magnitude on around March 25 then faded abruptly, beginning on April 13. It is likely in the process of disintegrating. It began the month in Pegasus at magnitude 7.1, but as of April 20 it may be magnitude 10. Look for large very diffuse coma. If anything survives, it will move into Triangulum by month's end.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~03:30 Low in the eastern sky during morning twilight at ~03:00 Low in the northern sky during morning twilight at ~02:20 Very low in the northern sky during morning twilight at ~02:10 1-
40o N Fairly high in the eastern sky during morning twilight at ~04:10 Fairly high in the eastern sky during morning twilight at ~04:20 Low in the eastern sky during morning twilight at ~04:00 Very low in the eastern sky during morning twilight at ~03:40 Very low in the eastern sky during morning twilight at ~03:40 1-
Equator Fairly high in the eastern sky at ~04:50 Low in the eastern sky during morning twilight at ~04:50 Very low in the eastern sky during morning twilight at ~05:10 Not visible Not visible 1-25
30o S Low in the eastern sky during morning twilight at ~05:00 Not visible Not visible Not visible Not visible 1-10

41P/Tuttle-Giacobini-Kresak: A morning comet visible in binoculars
This comet begins the month in Draco at magnitude 6.9. Look for a 20' coma. It should fade by about 0.9 magnitudes, moving into Hercules by month's end.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N High at ~01:00 High in moonlight at ~01:20 High at ~23:30 High at ~01:40 High at ~01:20 1-
40o N High at ~01:00 High in moonlight at ~01:40 High at ~22:40 High at ~03:10 High at ~03:00 1-
Equator Fairly high in the northern sky at ~01:00 Fairly high in the northern sky at ~04:40 Fairly high in moonlight at ~03:40 High at ~03:10 High at ~03:40 1-
30o S Not visible Not visible Very low in the northern sky in moonlight at ~03:30 Low in the northern sky at ~03:50 Low in the northern sky at ~03:40 13-

C/2015 V2 (Johnson): A morning comet visible in binoculars
This comet begins the month in Hercules at magnitude 9.2. Look for a 4' coma. It should brighten by about 1.0 magnitudes by month's end.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N High at ~03:00 High in moonlight at ~02:00 High at ~23:30 High at ~01:30 High at ~00:50 1-
40o N High at ~03:40 High in moonlight at ~02:10 High at ~22:40 High at ~02:00 High at ~01:20 1-
Equator High at ~03:50 Fairly high at ~04:40 High in moonlight at ~02:50 High at ~02:00 High at ~01:20 1-
30o S Low in the northern sky at ~03:50 Low in the northern sky at ~04:30 Low in the northern sky in moonlight at ~02:40 Low in the northern sky at ~02:00 Low in the northern sky at ~01:20 1-

2P/Encke: A morning comet visible in small telescopes
This comet begins the month in Aquarius at magnitude 8.9. Look for a 3' coma. It should fade rapidly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 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 25-27, 29-
Equator Low in the eastern sky during morning twilight at ~05:00 Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~05:00 Fairly high in the eastern sky during morning twilight at ~04:40 Fairly high at ~04:40 1-
30o S Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky at ~05:00 Fairly high during morning twilight at ~05:10 Fairly high in moonlight at ~05:00 High at ~05:00 1-

237P/LINEAR: A morning comet, perhaps visible in 8-inch telescopes
There are no recent observations for this comet, so the magnitudes may not be accurate. It begins the month in Pegasus, perhaps as bright as magnitude 10.5. Look for a ~2.5' coma. It should remain constant.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N Not visible Not visible Very low in the eastern sky during morning twilight at ~03:40 Very low in the eastern sky during morning twilight at ~03:20 Very low in the eastern sky during morning twilight at ~03:00 1-
40o N Very low in the eastern sky during morning twilight at ~04:30 Low in the eastern sky during morning twilight at ~04:30 Low in the eastern sky during morning twilight at ~04:10 Low in the eastern sky during morning twilight at ~03:50 Low in the eastern sky during morning twilight at ~03:40 1-
Equator Low in the eastern sky during morning twilight at ~05:00 Low in the eastern sky during morning twilight at ~05:00 Fairly high in the eastern sky during morning twilight at ~05:00 Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:50 1-
30o S Very low in the eastern sky during morning twilight at ~05:00 Low in the eastern sky during morning twilight at ~05:10 Low in the eastern sky during morning twilight at ~05:20 Low in the eastern sky during morning twilight at ~05:10 Fairly high in the eastern sky during morning twilight at ~05:10 1-

C/2017 E1 (Borisov): A morning comet visible in a 6-inch (15 cm) telescope
This comet begins the month in Aquarius at magnitude 9.2. Look for a 5' coma. It should fade by about 0.6 magnitudes, moving into Pisces by month's end.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible 1-3
40o N Very low in the eastern sky during morning twilight at ~04:30 Very low in the eastern sky during morning twilight at ~04:30 Very low in the eastern sky during morning twilight at ~04:20 Very low in the eastern sky during morning twilight at ~04:10 Not visible 1-
Equator Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high 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 ~04:50 1-
30o S Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~05:00 Fairly high in the eastern sky during morning twilight at ~05:10 Low in the eastern sky during morning twilight at ~05:10 Low in the eastern sky during morning twilight at ~05:10 1-

73P/Schwassmann-Wachmann: A southern hemisphere morning comet visible in a 10-inch (25 cm) telescope
This comet split last month 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 begin the month in Aquarius at magnitude 11.7 / 12.4 with comas of 1' and 1.5'. They should fade by about 1.2 magnitudes, moving into Cetus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER CHART
Latitude Visibility April 1 Visibility April 8 Visibility April 15 Visibility April 22 Visibility April 29 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 ~04:50 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 ~04:50 1-
30o S Fairly high in the eastern sky during morning twilight at ~04:50 Fairly high in the eastern sky during morning twilight at ~05:00 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 ~05:10 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

April 1st

April 15th

April 30th

Observations as of (UT)
Mag Diam Mag Diam Mag Diam
C/2015 ER61 (PANSTARRS) Capricornus 8.6 4.1' 6.1 8.2' 6.0? 8'? 2017 April 7 
41P/Tuttle-Giacobini-Kresak Draco 6.9 20.1' 6.9 18.4' 7.8 15.0' 2017 March 30
C/2017 E4 (Lovejoy) Pegasus 7.1 5.1' 10? ? ? ? 2017 March 28
2P/Encke Aquarius 8.9 2.8' 11.4 2.4' 13.2 2.2' 2017 March 27
C/2017 E1 (Borisov) Aquarius 9.2 5.0' 9.2 4.6' 9.7 4.3' 2017 March 28
C/2015 V2 (Johnson) Hercules 9.2 3.1' 8.7 3.6' 8.2 4.1' 2017 March 28
237P/LINEAR Pegasus 10.5? 2.6'? 10.6? 2.6'? 10.6? 2.6'? 2016 November 17
73P/Schwassmann-Wachmann Aquarius 11.7 56" 12.2 53" 12.9 50" 2017 March 6
73P-BT/Schwassmann-Wachmann Aquarius 12.4 1.5' 12.9 1.4' 13.6 1.3' 2017 March 25
45P/Honda-Mrkos-Pajdusakova Leo 13.6 2.2' 15.1 1.6' 16.5 1.2' 2017 March 20
C/2016 R2 (PANSTARRS) Eridanus 14.0 3.5' 13.9 3.5' 13.7 3.5' 2017 January 14
65P/Gunn Ophiuchus 14.5 1.5' 14.2 1.7' 14.1 1.8' 2017 January 4
315P/LONEOS Ursa Major 14.7 38" 14.9 35" 15.2 32" 2017 March 27
C/2016 VZ18 (PANSTARRS) Camelopardus 14.8 43" 15.4 41" 16.3 36" 2017 March 27
C/2016 N4 (MASTER) Pegasus 14.9? 17"? 14.7? 18"? 14.6? 18"? 2016 December 29
93P/Lovas Aries 15.0 20" 15.2 19" 15.4 19" 2017 March 27
C/2011 KP36 (Spacewatch) Cetus 15.0? 48" 15.0? 48" 15.1? 47" 2016 December 31
29P/Schwassmann-Wachmann Capricornus 15.1? 29"? 15.0? 30"? 14.9? 31"? 2016 November 1

*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