August was a busy month for comet watchers. In addition to observing 12P/Pons-Brooks in outburst and 9th magnitude C/2023 E1 (ATLAS) and C/2020 V2 (ZTF), a new bright amateur comet was discovered around mid-month. C/2023 P1 (Nishimura) is now 6th magnitude and should brighten to 4th-5th magnitude before being lost in the glare of the Sun. September will also see returning periodic comets 2P/Encke and 103P/Hartley brighten to 9th and 7th magnitude by the end of the month, respectively. 

Also, observable in September are C/2020 V2 (ZTF) at 9th magnitude, 12P/Pons-Brooks and C/2017 K2 (PANSTARRS) at 11th mag, C/2021 S3 (PANSTARRS) brightening from 12th to 11th magnitude, C/2021 T4 (Lemmon) fading from 10th to 11th magnitude, and C/2023 E1 (ATLAS) fading from 10th to 12th magnitude.

Last month the ALPO Comets Section received 277 observations of comets C/2023 P1 (Nishimura), C/2023 E1 (ATLAS), C/2023 A3 (Tsuchishan-ATLAS), C/2022 W3 (Leonard), C/2022 JK5 (PANSTARRS), C/2022 A2 (PANSTARRS), C/2021 X1 (Maury-Attard), C/2021 T4 (Lemmon), C/2021 S3 (PANSTARRS), C/2020 V2 (ZTF), C/2020 O2 (Amaral), C/2020 K1 (PANSTARRS), C/2019 T4 (ATLAS), C/2017 K2 (PANSTARRS), P/2014 W1 (PANSTARRS), 364P/PANSTARRS, 347P/PANSTARRS, 326P/Hill, 310P/Hill, 276P/Vorobjov, 242P/Spahr, 237P/LINEAR, 126P/IRAS, 103P/Hartley, 80P/Peters-Hartley, 41P/Tuttle-Giacobini-Kresak, 32P/Comas Sola, 12P/Pons-Brooks, and 2P/Encke. A big thanks to our August contributors: Dan Bartlett, Michel Besson, Michel Deconinck, J. J. Gonzalez, Jose Guilherme de Souza Aguiar, Andrew Hampton, Christian Harder, Scott Harrington, Carl Hergenrother, Eliot Herman, Michael Jäger, John Maikner, Martin Mobberley, Charles Morris, Gary T. Nowak, Mike Olason, Uwe Pilz, Ludovic Prebet, Michael Rosolina, Greg Ruppel, Greg Shanos, Tenho Tuomi, and Chris Wyatt.

The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.

This month we welcome two returning periodic comets breaking the 12th magnitude barrier. In April 2024, Halley-type comet 12P/Pons-Brooks will make its first perihelion passage since 1954. On July 20th, it experienced a 4- to 5-magnitude outburst and is now an 11th-magnitude object in the evening sky. Due to peak at 7th magnitude this October, 103P/Hartley is returning for the second time since its superb return in 2010. By the end of this month, 103P should brighten to magnitude 9.5 in the morning sky.

Also visible this month are 8th magnitude C/2021 T4 (Lemmon), 9th magnitude C/2020 V2 (ZTF) and C/2023 E1 (ATLAS), and 11th magnitude C/2017 K2 (PANSTARRS).

Last month the ALPO Comets Section received 180 observations of comets C/2023 E1 (ATLAS), C/2023 A3 (Tsuchishan-ATLAS), C/2022 W3 (Leonard), C/2022 E3 (ATLAS), C/2022 A2 (PANSTARRS), C/2021 T4 (Lemmon), C/2020 V2 (ZTF), C/2020 K1 (PANSTARRS), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), 237P/LINEAR, 126P/IRAS, 103P/Hartley, 80P/Peters-Hartley, 32P/Comas Sola, 12P/Pons-Brooks, and 2P/Encke. A big thanks to our July contributors: Dan Bartlett, J. J. Gonzalez, Jose Guilherme de Souza Aguiar, Christian Harder, Carl Hergenrother, Eliot Herman, John Maikner, Martin Mobberley, Charles Morris, Gary T. Nowak, Uwe Pilz, Michael Rosolina, Greg Shanos, Tenho Tuomi, and Chris Wyatt.

The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.

July will be a nice month for comet watchers. While there are no “bright” comets, three comets should make nice targets for binoculars or small telescopes. The brightest comet of the month, 7th magnitude C/2021 T4 (Lemmon), will be well placed for southern hemisphere observers as it races from the morning into the evening sky. Northern observers will be able to observe it early in the month though a bright Moon and a decreasing elevation will make it a bit challenging. Northern observers will have 9th magnitude C/2023 E1 (ATLAS) all to themselves as it moves through the northern circumpolar sky. Both hemispheres can observe 9-10th magnitude C/2020 V2 (ZTF) in the morning sky. Imagers are asked to watch one of next year’s potential bright objects, C/2023 A3 (Tsuchinshan-ATLAS), at 16th magnitude in the evening sky.

Last month the ALPO Comets Section received 99 magnitude estimates, images, and sketches of comets C/2023 E1 (ATLAS), C/2023 A3 (Tsuchishan-ATLAS), C/2022 E3 (ATLAS), C/2022 A2 (PANSTARRS), C/2021 T4 (Lemmon), C/2021 S3 (PANSTARRS), C/2020 V2 (ZTF), C/2020 K1 (PANSTARRS), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 364P/PANSTARRS, 276P/Vorobjov, 237P/LINEAR, 126P/IRAS, 77P/Longmore, 71P/Clark, and 12P/Pons-Brooks. A big thanks to our June contributors: J. J. Gonzalez, Jose Guilherme de Souza Aguiar, Christian Harder, Carl Hergenrother, Eliot Herman, John Maikner, Michael Rosolina, and Chris Wyatt..

The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.

May was a quiet month for comet watchers as the sky was lacking in bright or even semi-bright comets. June should bring some improvement. C/2020 V2 (ZTF), which has been around magnitude 9.0 to 9.5 for most of the year, is again visible after passing solar conjunction. C/2021 T4 (Lemmon) and C/2023 E1 (ATLAS) are expected to start the month at 10th magnitude and reach magnitude 9 by the end of the month. C/2021 T4 (Lemmon) is primarily an object for southern hemisphere observers, while C/2023 E1 (ATLAS) is a northern-only object.

Last month the ALPO Comets Section received 60 magnitude estimates and images/sketches of comets C/2023 E1 (ATLAS), C/2023 A3 (Tsuchishan-ATLAS), C/2021 T4 (Lemmon), C/2020 K1 (PANSTARRS), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 364P/PANSTARRS, 263P/Gibbs, 237P/LINEAR, 199P/Shoemaker, 133P/Elst-Pizarro, 130P/McNaught-Hughes, 99P/Kowal, 96P/Machholz, 81P/Wild, 219P/LINEAR, 103P/Hartley, 80P/Peters-Hartley, 77P/Longmore, 71P/Clark, and 12P/Pons-Brooks. A big thanks to our May contributors: J. J. Gonzalez, Jose Guilherme de Souza Aguiar, Carl Hergenrother, John Maikner, and Chris Wyatt.

The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.

We are in a bit of a bright comet drought at the moment. Most of the brighter comets of early 2023 have now faded with only one still brighter than magnitude 10, C/2020 V2 (ZTF), which is too close to the Sun in May to observe.

There are several fainter comets visible between magnitude 10 and 12 this month. Two new comets to this newsletter are breaking the magnitude 12 barrier on their way to becoming even brighter in the months ahead. Though C/2021 T4 has been unobservable for much of the last 3 months, its brightening trend up till January suggested a peak brightness around magnitude 8.0 in July. Newly discovered C/2023 E1 (ATLAS) is on an 85-year orbit and has rapidly brightened to around 12-13th magnitude. It should peak at magnitude 10 or even brighter in July and August.

Last month the ALPO Comets Section received 108 magnitude estimates and 16 images/sketches of comets C/2023 E1 (ATLAS), P/2023 B1 (PANSTARRS), C/2023 A3 (Tsuchishan-ATLAS), C/2022 E3 (ZTF), C/2022 A2 (PANSTARRS), C/2020 V2 (ZTF), C/2020 K1 (PANSTARRS), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), P/2010 WJ5 (Catalina), P/2010 VH95 (Catalina), 452P/Shappard-Jewitt, 393P/Spacewatch-Hill, 364P/PANSTARRS, 299P/Catalina-PANSTARRS, 263P/Gibbs, 237P/LINEAR, 199P/Shoemaker, 133P/Elst-Pizarro, 130P/McNaught-Hughes, 99P/Kowal, 96P/Machholz, 81P/Wild, 77P/Longmore, 71P/Clark, 67P/Churyumov-Gerasimenko, 19P/Borrelly, and 12P/Pons-Brooks. A big thanks to our March contributors: Dan Bartlett, Denis Buczynski, J. J. Gonzalez, Jose Guilherme de Souza Aguiar, Christian Harder, Carl Hergenrother, John Maikner, Martin Mobberley, Mike Olason, Uwe Pilz, Efrain Morales Rivera, Gregg Ruppel, Greg T. Shanos, and Chris Wyatt.

The monthly ALPO Comet News PDF can be found here. A shorter version of this report is posted on a dedicated Cloudy Nights forum. All are encouraged to join the discussion over at Cloudy Nights.