Comet Section        


July 8, 2021 – ALPO Comet News for July 2021


We are still in the midst of a bright comet drought. The brightest comets of July should be around magnitude 10.0. These include two comets that ranked among the “brightest” last month, C/2020 T2 (Palomar) and 7P/Pons-Winnecke. Joining them around the magnitude 10.0 level will be another short-period comet, 15P/Finlay, which should reach its brightest at the end of July into early August. Between 11th and 13th magnitude are a number of other comets such as 4P/Faye, 8P/Tuttle, C/2017 K2 (PANSTARRS), and C/2019 L3 (ATLAS). Imagers are encouraged to continue monitoring inbound C/2021 A1 (Leonard). While this comet still has the potential to be a notable object at the end of the year, that hope is fading as the comet has been slow to brighten. Among newly discovered objects, C/2014 UN271 (Bernardinelli-Bernstein) ranks as one of the most interesting discoveries in some time. This object is still 10 years away from an extremely large perihelion distance of 10.95 au. Bernardinelli-Bernstein has already been imaged going back to 2014 and it is possible modestly equipped imagers may be able to follow it as an active object for another 20 years!

Comets Section News

Since June 1, the ALPO Comets Section received 15 images and/or sketches from John Chumack, Michel Deconinck, Jim Filipski, Carl Hergenrother, Martin, Mobberley, Mike Olason, John D. Sabia, and Tenho Tuomi of the following comets: 4P/Faye, 6P/d’Arrest, 7P/Pons-Winnecke, 8P/Tuttle, 15P/Finlay, 57P/du Toit-Neujmin-Delporte, 108P/Schuster, 246P/NEAT, C/2020 J1 (SONEAR), C/2020 T2 (Palomar), C/2021 A1 (Leonard), C/2021 D2 (ATLAS), P/2021 J3 (ATLAS), and an oldie but goodie of C/1975 V1 (West).

Also since June 1, the Section has received 58 magnitude measurements from Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, and Chris Wyatt of comets 7P/Pons-Winnecke, 10P/Tempel, 15P/Finlay, 67P/Churyumov-Gerasimenko, 117P/Helin-Roman-Alu, 246P/NEAT, C/2017 K2 (PANSTARRS), C/2018 U1 (Lemmon), C/2019 F1 (ATLAS-Africano), C/2019 L3 (ATLAS), C/2019 T4 (ATLAS), C/2020 F5 (MASTER), C/2020 J1 (SONEAR), C/2020 R4 (ATLAS), C/2020 S3 (Erasmus), C/2020 T2 (Palomar), and C/2021 A1 (Leonard).

In addition to observations submitted to the ALPO, we also occasionally use data submitted to other sources for our analysis. We acknowledge with thanks the comet observations from the International Comet Quarterly, the Minor Planet Center, the COBS Comet Observation Database, and our own ALPO contributors used in this report.

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.

- Carl Hergenrother

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