Comet Chasing - Comets Visible in September 2026, by Aperture

There is one comet visible in binoculars from both hemispheres this month, 10P/Tempel, and one more visible in small telescopes, 220P/McNaught. Six more are visible in larger telescopes. See the Observing Synopses for which comets are visible from your latitude, the best dates and the time of night.

Visibility predictions here use SkyTools code that accounts for magnitude, coma diameter, and degree of condensation from recent observations (rather than magnitude alone.) When we say a comet needs a 14-inch scope, it means the comet is detectable in the eyepiece at that aperture from a Bortle 5 (country/suburban) site (or a dark site if indicated).

General Comet Information

10P/Tempel is a periodic comet with an orbital period of 5.4 years. Perihelion was on August 2, 2026 at a distance of 1.4 AU.
220P/McNaught is a periodic comet with an orbital period of 5.5 years. It had a new outburst early last month. As of August 7, it had brightened to magnitude 7, the coma had grown to 7.5 arc minutes, and there was a 21 arc minute tail. It has been fading regularly ever since. As of September 1, it is 11th magnitude.
169P/NEAT is a periodic comet with an orbital period of 45.2 years. It will reach perihelion on September 21. It passed within 0.17 AU of the Earth on August 11. It is predicted to reach maximum brightness of magnitude 13 in early September.
C/2024 T5 (ATLAS) will pass perihelion in early May 2027. It is currently predicted to reach maximum brightness of magnitude 13.3 in mid April.
88P/Howell is a periodic comet with an orbital period of 5.5 years. It passed perihelion in March 2026 at a distance of 1.4 AU.
29P/Schwassmann-Wachmann has frequent outbursts, typically resulting in a brightening of 1-4.0 magnitudes. It varies in its distance from the Sun from 5.8 AU (at perihelion) to 6.3 AU (at aphelion), which is an unusually small variation for a comet, and remains quite far from the sun at all times. This means that it can be observed more or less continuously. See [Mission 29P](https://britastro.org/section_information_/comet-section-overview/mission-29p-2) from the BAA for up to date information.
C/2024 J3 (ATLAS) will pass perihelion in late November. It is predicted to reach maximum brightness of magnitude 14.5 in early November.
78P/Gehrels is a periodic comet with an orbital period of 7.2 years that passed perihelion in late June. It is predicted to obtain maximum brightness of magnitude 13 in mid November.
260P/McNaught is a periodic comet with an orbital period of 6.9 years that passed perihelion in early August.
161P/Hartley-IRAS is a periodic comet with an orbital period of 21.5 years. It will reach perihelion in late November when it is predicted to reach maximum brightness of magnitude 12.5 in early November.
C/2025 R3 (PANSTARRS) passed perihelion on April 19.
C/2026 A2 (Bok) will reach perihelion in late December. It is predicted to reach maximum brightness of magnitude 13.5 in early December.
C/2024 R4 (PANSTARRS) will reach perihelion in late October 2027. It is predicted to reach maximum brightness of magnitude 14 in late February 2028.
C/2014 UN271 (Bernardinelli-Bernstein) is an interesting Oort cloud comet that was reported as a result of the Dark Energy Survey. Soon after it was made public, images showed a cometary coma. Discovery credit goes to Pedro Bernardinelli and Gary Bernstein. This is a remarkable comet that was at 29 AU in 2014, with a perihelion of 10.9 AU in 2031. Its orbit extends out to 40,000 AU! It was unusually bright for its distance. HST observations that isolate the nucleus estimate the diameter to be between 120 and 140 km, making this possibly the largest comet nucleus yet measured. Because of its distant perihelion, this comet is not expected to become bright enough to be visually observed except in large instruments, and not until the end of the decade, but it is likely going to be the subject of intense scientific scrutiny.

Comets that have apparently disintegrated: C/2026 A1 (MAPS), SWAN26B, 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 a comet still exists!

Comet Visibility in the Eyepiece

Magnitude alone is a poor guide to whether a comet can be seen. This page uses the SkyTools visibility model, which also considers coma diameter, degree of condensation, sky brightness, the moon, and the aperture in use. The dates below are the nights the comet should be perceptible — visible with reasonable confidence, but not necessarily easy. The last night listed is the least certain, since it is the night the comet crosses that threshold; expect it to move by a day either way with your sky and your optics. The times given are the optimum time to look. 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 September

Times are local standard time. Add one hour where daylight saving or summer time is in effect. Times are approximate and vary with your latitude, so go out well before the time given. .

10P/Tempel: An evening comet visible in binoculars at a dark site

This comet begins the month in Piscis Austrinus at magnitude 9.1. Look for a 5' coma, center much brighter than edges, though still diffuse. It should fade rapidly. The best visibility is early in the month as seen from the southern hemisphere. FINDER CHART

Visibility of 10P/Tempel by latitude, September 2026
Latitude	Visibility
55° N	Not perceptible.
40° N	Perceptible in a 4-inch (10 cm) telescope from a dark site near midnight from the 1st/2nd through the 14th/15th, low in the south throughout. In a 6-inch (15 cm) telescope it is perceptible from the 1st/2nd through the 19th/20th.
Equator	Perceptible in binoculars from a dark site near midnight from the 1st/2nd through the 7th/8th. In a 4-inch (10 cm) telescope it is easy from the 1st/2nd through the 3rd/4th, then perceptible through the 21st/22nd.
30° S	Perceptible in binoculars from a dark site near midnight from the 1st/2nd through the 9th/10th. In a 4-inch (10 cm) telescope it is easy from the 1st/2nd through the 5th/6th, then perceptible through the 21st/22nd, then on the 28th/29th.

220P/McNaught: A morning comet visible in small telescopes at a dark site

This comet begins the month in Cetus at magnitude 10.4. Look for a 3.5' coma, diffuse condensation at center. It had a significant outburst on August 6 and is still fading by about one magnitude every 6 days. We expect it to settle at about 13th magnitude by mid month. Because we can't easily model it as it fades from the outburst we are only including predictions for the first half of the month. It will probably require a larger telescope by then. It will move into Taurus by month's end. The best visibility is early in the month. FINDER CHART

Visibility of 220P/McNaught by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in a 4-inch (10 cm) telescope from a dark site from the 4th/5th.
40° N	Perceptible in a 4-inch (10 cm) telescope from a dark site in the pre-dawn sky starting on the 5th.
Equator	Perceptible in a 4-inch (10 cm) telescope from a dark site from the 4th/5th. In a 6-inch (15 cm) telescope it is perceptible from the 3rd/4th through the 6th/7th.
30° S	Perceptible in a 4-inch (10 cm) telescope from a dark site styarting on the 3rd/4th.

161P/Hartley-IRAS: An all night comet visible in a 6-inch (15 cm) telescope at a dark site

This comet begins the month in Eridanus at magnitude 14.9. Look for a 40" coma. It should brighten rapidly, moving into Aquarius by month's end. The best visibility is late in the month as seen from the southern hemisphere. FINDER CHART

Visibility of 161P/Hartley-IRAS by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in a 12.5-inch (32 cm) telescope from a dark site near midnight from the 21st/22nd through the 23rd/24th, then on the 30th/October 1st, fairly high in the south throughout.
40° N	Perceptible in an 8-inch (20 cm) telescope from a dark site in the evening on the 30th, fairly high in the east throughout. In a 10-inch (25 cm) telescope it is perceptible from the 20th/21st through the 23rd/24th, then on the 29th/30th and 30th/October 1st.
Equator	Perceptible in a 6-inch (15 cm) telescope from a dark site in the evening on the 29th and 30th. In an 8-inch (20 cm) telescope it is perceptible from the 20th/21st through the 22nd/23rd, then from the 28th/29th through the end of the month.
30° S	Perceptible in a 6-inch (15 cm) telescope from a dark site in the evening on the 29th and 30th.

C/2024 T5 (ATLAS): A morning comet visible in a 10-inch (25 cm) telescope at a dark site

This comet begins the month in Lepus at magnitude 13.9. Look for a 45" coma, diffuse condensation at center. It should brighten slowly. The best visibility is late in the month. FINDER CHART

Visibility of C/2024 T5 (ATLAS) by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in an 18-inch (46 cm) telescope from a dark site in morning twilight from the 23rd through the 25th, low in the south throughout. In a 24-inch (61 cm) telescope it is perceptible from the 14th through the 25th.
40° N	Perceptible in a 12.5-inch (32 cm) telescope from a dark site in the pre-dawn sky on the 24th and 25th, fairly high throughout. In a 14-inch (36 cm) telescope it is perceptible from the 14th through the 25th.
Equator	Perceptible in a 10-inch (25 cm) telescope from a dark site in the pre-dawn sky from the 20th through the 25th. In a 12.5-inch (32 cm) telescope it is perceptible from the 7th/8th through the 24th/25th.
30° S	Perceptible in a 10-inch (25 cm) telescope from a dark site in the pre-dawn sky from the 20th through the 24th. In a 12.5-inch (32 cm) telescope it is perceptible from the 7th through the 24th.

169P/NEAT: A northern hemisphere morning comet visible in an 18-inch (46 cm) telescope at a dark site

This comet begins the month in Leo at magnitude 12.9. Look for a 45" coma. It should fade rapidly, moving into Sextans by month's end. The best visibility is mid-month. FINDER CHART

Visibility of 169P/NEAT by latitude, September 2026
Latitude	Visibility
55° N	Not perceptible.
40° N	Perceptible in a 24-inch (61 cm) telescope from a dark site in morning twilight from the 14th through the 25th, very low in the east at first, climbing higher as the month goes on.
Equator	Perceptible in an 18-inch (46 cm) telescope from a dark site in morning twilight from the 14th through the 25th, low in the east throughout.
30° S	Not perceptible.

C/2023 R1 (PANSTARRS): A southern hemisphere evening comet visible in an 18-inch (46 cm) telescope at a dark site

This comet begins the month in Libra at magnitude 14.8. Look for a 30" coma, condensation is a diffuse spot in coma center; moderately condensed. It should fade slowly. The best visibility is early in the month as seen from the southern hemisphere. FINDER CHART

Visibility of C/2023 R1 (PANSTARRS) by latitude, September 2026
Latitude	Visibility
55° N	Not perceptible.
40° N	Not perceptible.
Equator	Perceptible in an 18-inch (46 cm) telescope from a dark site in the evening from the 1st through the 6th. In a 24-inch (61 cm) telescope it is perceptible from the 1st through the 14th.
30° S	Perceptible in an 18-inch (46 cm) telescope from a dark site in the evening from the 1st through the 7th. In a 24-inch (61 cm) telescope it is perceptible from the 1st through the 14th.

C/2024 J3 (ATLAS): A far-northern evening comet visible in a 24-inch telescope at a dark site

This comet begins the month in Lyra at magnitude 14.3. Look for a 60" coma, diffuse condensation at center. It should remain constant. The best visibility is early in the month as seen from the northern hemisphere. FINDER CHART

Visibility of C/2024 J3 (ATLAS) by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in a 24-inch (61 cm) telescope from a dark site from the 3rd/4th through the 19th/20th, moving from evening twilight to the evening as the month goes on.
40° N	Perceptible in a 24-inch (61 cm) telescope from a dark site in the evening from the 1st through the 18th, then on the 29th and 30th.
Equator	Not perceptible.
30° S	Not perceptible.

78P/Gehrels: A northern hemisphere morning comet visible in a 24-inch telescope at a dark site

This comet begins the month in Gemini at magnitude 14.6. Look for a 35" coma, diffuse condensation at center. It should remain constant. The best visibility is late in the month. FINDER CHART

Visibility of 78P/Gehrels by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in a 24-inch (61 cm) telescope from a dark site in the pre-dawn sky from the 16th through the 24th, fairly high throughout.
40° N	Perceptible in a 24-inch (61 cm) telescope from a dark site in the pre-dawn sky from the 8th through the 25th, fairly high at first, climbing higher as the month goes on.
Equator	Perceptible in a 24-inch (61 cm) telescope from a dark site from the 7th/8th through the 24th/25th, moving from before dawn to morning twilight as the month goes on.
30° S	Not perceptible.

260P/McNaught: A northern hemisphere morning comet visible in a 24-inch telescope at a dark site

This comet begins the month in Perseus at magnitude 14.8. Look for a 40" coma, condensation is a diffuse spot in coma center; moderately condensed. It should fade slowly, moving into Auriga by month's end. The best visibility is early in the month as seen from the northern hemisphere. FINDER CHART

Visibility of 260P/McNaught by latitude, September 2026
Latitude	Visibility
55° N	Perceptible in a 24-inch (61 cm) telescope from a dark site from the 6th/7th through the 24th/25th, moving from before dawn to morning twilight as the month goes on.
40° N	Perceptible in a 24-inch (61 cm) telescope from a dark site from the 6th/7th through the 24th/25th, moving from before dawn to morning twilight as the month goes on.
Equator	Perceptible in a 24-inch (61 cm) telescope from a dark site in the pre-dawn sky from the 8th through the 24th.
30° S	Not perceptible.

Summary Data for This Month's Telescopic Comets

Comets reaching magnitude 16 or brighter during September 2026. Constellation is where the comet stood on the first of the month. The last column gives the date of the most recent observation used to compute these values; a question mark marks values extrapolated from observations more than a month old.
Comet	Constellation	September 1st		September 15th		September 30th		Observations as of (UT)
Comet	Constellation	Mag	Diam	Mag	Diam	Mag	Diam	Observations as of (UT)
10P/Tempel	Piscis Austrinus	9.1	4.8′	9.9	4.2′	11.0	3.5′	2026 August 23
220P/McNaught	Cetus	10.4	3.3′	10.4	3.4′	10.5	3.6′	2026 August 24
169P/NEAT	Leo	12.9	45″	13.7	27″	14.7	18″	2026 August 18
C/2024 T5 (ATLAS)	Lepus	13.9	43″	13.7	45″	13.6	48″	2026 August 12
29P/Schwassmann-Wachmann	Virgo	14.1	47″	14.1	46″	14.1	46″	2026 August 13
88P/Howell	Aries	14.2	1.1′	14.5	1.2′	14.8	1.2′	2026 August 22
C/2024 J3 (ATLAS)	Lyra	14.3	58″	14.3	57″	14.4	55″	2026 August 12
78P/Gehrels	Gemini	14.6	35″	14.6	37″	14.6	39″	2026 August 23
C/2023 R1 (PANSTARRS)	Libra	14.8	28″	15.0	26″	15.3	25″	2026 August 20
260P/McNaught	Perseus	14.8	38″	14.9	39″	15.0	40″	2026 July 28
161P/Hartley-IRAS	Eridanus	14.9	40″	13.6	58″	12.4	1.3′	2026 July 24
C/2025 R3 (PANSTARRS)	Puppis	15.0?	1.5′?	15.4?	1.5′?	15.8?	1.5′?	2026 June 25
C/2026 A2 (Bok)	Ursa Minor	15.2	48″	14.9	52″	14.5	57″	2026 August 10
C/2024 R4 (PANSTARRS)	Cygnus	15.3	30″	15.2	30″	15.1	30″	2026 July 28
63P/Wild	Virgo	15.9?	37″?	16.1?	36″?	16.3?	35″?	2026 June 19

* In solar conjunction and generally not visible

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

Maintained by Greg Crinklaw, since 2003.

Comet Chasing in September 2026