Comet Chasing in September

Comet chasing is the visual observation of telescopic comets.

News

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.

 

Make your own custom charts and predictions for your location and equipment: software for comet observing

Comet Synopses for September

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

Charts look poor or grainy? Read this.

103P/Hartley: An evening comet visible in binoculars
This comet begins the month in Lacerta at magnitude 11.5. Look for a 2.5' coma. It should brighten rapidly, moving into Cassiopeia by month's end.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N High at ~00:00 High at ~23:40 High at ~01:10 High in moonlight at ~23:50 High at ~23:50 1-
40o N High at ~00:00 High at ~23:40 High at ~02:00 High in moonlight at ~23:50 High at ~00:20 1-
Equator High at ~00:00 High at ~23:40 Fairly high in the northern sky at ~02:50 Low in the northern sky at ~19:30 Fairly high at ~00:20 1-
30o S Fairly high in the northern sky at ~00:00 Low in the northern sky at ~23:40 Not visible Not visible Not visible 1-

10P/Tempel: A morning comet visible in small telescopes
This comet begins the month in Cetus at magnitude 9.0. Look for a 4' coma. It should fade by about 1.1 magnitudes by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N Low in the southern sky in moonlight at ~02:40 Low in the southern sky at ~02:20 Low in the southern sky at ~01:50 Low in the southern sky in moonlight at ~01:20 Low in the southern sky at ~23:50 1-
40o N Fairly high in moonlight at ~02:50 Fairly high at ~02:20 Fairly high at ~02:00 Fairly high in moonlight at ~01:20 Fairly high in the southern sky at ~00:40 1-
Equator High at ~02:40 High at ~02:20 High at ~02:50 High in moonlight at ~01:20 High at ~00:40 1-
30o S High at ~02:40 High at ~02:20 High at ~03:30 Fairly high in the eastern sky at ~20:10 High at ~00:40 1-

C/2009 P1 (Garradd): An evening comet visible in an 8-inch telescope
This comet begins the month in Grus at magnitude 12.7. Look for a 45" coma. It should brighten slowly. The best visibility is late in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky at ~00:10 Low in the southern sky at ~23:30 Low in the southern sky in moonlight at ~23:00 Low in the southern sky in moonlight at ~22:20 Low in the southern sky at ~21:50 1-
Equator High at ~00:10 High at ~23:30 Fairly high in the western sky at ~02:50 Fairly high at ~19:30 High at ~21:50 1-
30o S High at ~00:10 High at ~23:30 Fairly high at ~03:30 High at ~20:10 High at ~21:50 1-

C/2009 R1 (McNaught): A southern hemisphere morning comet visible in an 8-inch telescope
This comet begins the month in Antlia at magnitude 12.1. Look for a 1' coma. It should fade rapidly, moving into Vela by month's end. The best visibility is late in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 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 Not visible Not visible Not visible Very low in the southern sky during morning twilight at ~04:50 21-21, 30-
30o S Low in the eastern sky during morning twilight at ~05:10 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 ~04:40 Fairly high in the eastern sky during morning twilight at ~04:30 1-

65P/Gunn: An evening comet visible in a 10-inch telescope
This comet begins the month in Microscopium at magnitude 12.1. 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 September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible  
40o N Low in the southern sky at ~21:40 Low in the southern sky at ~21:10 Low in the southern sky in moonlight at ~20:40 Low in the southern sky in moonlight at ~20:30 Low in the southern sky at ~19:50 1-
Equator High at ~21:40 High at ~21:10 High in moonlight at ~20:40 High at ~19:30 High at ~19:50 1-
30o S High at ~21:40 High at ~21:30 High in moonlight at ~20:40 High at ~20:10 High at ~19:50 1-

C/2009 K5 (McNaught): A northern hemisphere morning comet visible in a 12.5-inch telescope
This comet begins the month in Lynx at magnitude 11.0. Look for a 3' coma. It should fade slowly.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N Fairly high during morning twilight at ~03:00 High during morning twilight at ~03:20 High at ~03:30 High during morning twilight at ~04:00 High in moonlight at ~04:00 1-
40o N Fairly high during morning twilight at ~04:00 High at ~04:10 High at ~04:10 High during morning twilight at ~04:30 High in moonlight at ~04:30 1-
Equator Low in the northern sky during morning twilight at ~05:00 Low in the northern 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 during morning twilight at ~04:50 Fairly high in the northern sky during morning twilight at ~04:40 1-
30o S Not visible Not visible Not visible Not visible Not visible  

2P/Encke: A southern hemisphere evening comet visible in a 14-inch telescope
This comet begins the month in Corvus at magnitude 9.9. Look for a 4' coma. It should fade rapidly, moving into Scorpius by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 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 western sky during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~19:00 Fairly high in the western sky during evening twilight at ~19:00 Fairly high during evening twilight at ~19:00 1-
30o S Fairly high in the western sky during evening twilight at ~19:00 Fairly high during evening twilight at ~19:10 Fairly high during evening twilight at ~19:00 Fairly high during evening twilight at ~19:20 Fairly high during evening twilight at ~19:20 1-

C/2006 W3 (Christensen): A southern hemisphere evening comet visible in an 18-inch telescope
This comet begins the month in Ara at magnitude 12.0. Look for a 2.5' coma. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 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 High at ~19:20 Fairly high in moonlight at ~19:10 Fairly high during evening twilight at ~19:00 Fairly high at ~19:00 Fairly high during evening twilight at ~19:00 1-
30o S High at ~19:10 High in moonlight at ~19:20 High during evening twilight at ~19:10 High at ~19:20 High at ~19:20 1-

81P/Wild: An evening comet visible in very large telescopes
This comet begins the month in Libra at magnitude 13.1. Look for a 1' coma. It should fade by about 0.9 magnitudes, moving into Ophiuchus by month's end. The best visibility is early in the month as seen from the southern hemisphere.  FINDER_CHART
Latitude Visibility September 4 Visibility September 11 Visibility September 18 Visibility September 25 Visibility October 2 Nights Visible
55o N Very low in the western sky during evening twilight at ~20:20 Very low in the southern sky during evening twilight at ~19:50 Not visible Not visible Not visible 1-14
40o N Fairly high in the southern sky during evening twilight at ~19:50 Low in the southern sky during evening twilight at ~19:40 Low in the southern sky during evening twilight at ~19:10 Low in the southern sky during evening twilight at ~19:00 Low in the southern sky during evening twilight at ~19:00 1-
Equator High at ~19:10 High in moonlight at ~19:10 High during evening twilight at ~19:00 High during evening twilight at ~19:00 High during evening twilight at ~19:00 1-
30o S High at ~19:10 High in moonlight at ~19:10 High during evening twilight at ~19:00 High at ~19:20 High during evening twilight at ~19:20 1-

 

Summary Data for This Month's Telescopic Comets

Here's a list of the 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

September 1st

September 15th

September 30th

 Observations as of (UT)
Mag Diam Mag Diam Mag Diam
10P/Tempel Cetus 9.0 4.0' 9.5 3.9' 10.1 3.6' 2010 August 21
2P/Encke Corvus 9.9 4.0' 12.0 3.7' 13.9 3.2' 2010 August 28
C/2009 K5 (McNaught) Lynx 11.0 3.1' 11.3 3.1' 11.5 3.2' 2010 August 20
103P/Hartley Lacerta 11.5 1.2' 10.1 1.7' 8.6 2.6' 2010 August 22
C/2006 W3 (Christensen) Ara 12.0 2.7' 12.2 2.5' 12.4 2.3' 2010 August 4
65P/Gunn Microscopium 12.1 1.1' 12.3 1.0' 12.6 55" 2010 August 7
C/2009 R1 (McNaught) Antlia 12.1 1.2' 12.9 1.1' 13.7 1.0' 2010 June 28
C/2009 P1 (Garradd) Grus 12.7 45" 12.5 46" 12.4 46" 2010 August 20
81P/Wild Libra 13.1 1.0' 13.5 54" 13.9 49" 2010 August 7
C/2007 Q3 (Siding Spring) Bootes 14.7 40" 14.9 38" 15.1 37" 2010 August 4

*In solar conjunction and 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
Astronomical Headlines (IAU)
Cometography