Comet Chasing in May


Comet chasing is the visual observation of telescopic comets.  Jump to:  Observing synopses    Summary data    Buy me a Coffee 

We've been doing this page for 20 years, and have never seen so few comets available in amateur telescopes. For most observers, at least an 18-inch telescope will be required to see a comet this month. Some part of that is due to changes in our algorithms, but its primarily due to a true lack of observable comets. Remember, what sets this page apart from others is that we claculate whether or not a comet is actually visible in a telescope, rather than just report its magnitude. See the Observing Synopses for which comets are visible from your latitude, the best dates and the time of night.

Comets that have apparently disintegrated: C/2025 F2, C/2024 G3, C/2024 S1 (ATLAS), C/2022 S3 (PANSTARRS), C/2021 P4 (ATLAS), C/2020 Q1 (Borisov), C/2020 P1 (NEOWISE), and C/2019 Y4 (ATLAS). Beware that various sources often fail to keep track of whether or not a comet still exists!

Comet Visibility in the Eyepiece

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. 

 

This page uses code developed for SkyTools to predict the visibility of a comet.  Predicting how much aperture is required to see a comet is a very complex task. The magnitude alone is a very poor predictor.  SkyTools considers the magnitude, coma diameter, and degree of concentration of the comet, based on recent observations.The predictions are made for a Country/Suburban site, which is approximately Bortle 5, unless indicated otherwise. 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! 

Observing Synopses for May


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

C/2021 G2 (Atlas): A morning comet visible in an 18-inch (46 cm) telescope at a dark site
This comet begins the month in Libra at magnitude 13.8. Look for a 1' coma, diffuse condensation at center. It should fade slowly.  FINDER CHART

Latitude Visibility May 3 Visibility May 10 Visibility May 17 Visibility May 24 Visibility May 31 Nights Visible
55o N Not visible Not visible Not visible Not visible Not visible 1-6, 13-27
40o N High at ~00:40 Not visible High at ~23:30 High at ~23:00 High in moonlight at ~22:40 1-9, 13-
Equator High at ~00:40 Not visible High at ~22:30 High at ~23:00 High at ~22:30 1-9, 14-
30o S High at ~00:40 Not visible High at ~21:40 High at ~23:00 High at ~22:30 1-9, 15-

Summary Data for This Month's Telescopic Comets


Comets brighter than 16th 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
29P/Schwassmann-Wachmann Leo 12.6 2.9' 12.6 2.8' 12.7 2.7' 2025 April 30
C/2021 G2 (Atlas) Libra 13.8 1.1' 13.9 1.1' 13.9 1.0' 2025 April 30
C/2023 A3 (Tsuchinshan-ATLAS) Vulpecula 14.7 47" 14.9 48" 15.1 48" 2025 April 29
C/2022 E2 (ATLAS) Andromeda 15.1 39" 15.1 38" 15.2 38" 2025 April 27
49P/Arend-Rigaux Taurus 15.1 1.2' 15.4 1.2' 15.8 1.1' 2025 April 29
C/2022 N2 (PANSTARRS) Pisces 15.2? 28"? 15.1? 29"? 15.0? 30"? 2025 February 3
C/2023 C2 (ATLAS) Pegasus 15.3 1.2' 15.4 1.2' 15.5 1.2' 2025 April 29
C/2024 L5 (ATLAS) Corvus 15.5 32" 15.7 29" 15.9 26" 2025 April 30
C/2024 J2 (Wierzchos) Pisces 15.6? 35"? 15.8? 35"? 15.9? 36"? 2025 February 2
P/2010 H2 (Vales) Virgo 15.8 38" 15.9 37" 16.0 34" 2025 April 30
C/2023 T3 (Fuls) Centaurus 15.8 36" 15.9 34" 16.1 33" 2025 March 31
C/2022 QE78 (ATLAS) Gemini 15.9 28" 15.9 27" 15.9 26" 2025 April 29
C/2024 J3 (ATLAS) Sagittarius 16.2 29" 16.0 30" 15.8 32" 2025 April 30
65P/Gunn Sagittarius 16.2 24" 16.1 25" 15.9 27" 2025 April 30
*In solar conjunction and generally not visible 

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

Make your own visual observing custom charts for your location and telescope/binoculars: Software for visual comet observing 

Select comets that are appropriate for your imaging system, and plan when they are best imaged: Software for comet imaging 
 

Links

Skyhound's Guide to Comets
Skyhound's Guide to Finding Comets
BAA Comet Section
Weekly Information About Bright Comets
Cometography