Comet Section        


September 6, 2021 – ALPO Comet News for September 2021


While we are still waiting for the next “Big One” or even the next “Bright Enough to be Seen in my Binoculars” comet, September sees quite a few comets bubbling around magnitude 10 to 11. 8P/Tuttle may get as bright as magnitude 8.5 though it is solely a southern hemisphere object. As many as 5 comets, 4P/Faye, 6P/d’Arrest, 67P/Churyumov-Gerasimenko, C/2019 L3 (PANSTARRS), and C/2020 T2 (PANSTARRS), could brighten into the magnitude 10 to 11 range.

C/2021 A1 (Leonard) still has the potential to be an interesting object this December. Recent observations suggest it may be brightening at a fast rate, so imagers and large aperture visual observers are encouraged to observe it this month as it may brighten to 12-13th magnitude by the end of the month.

Comets Section News

During August, the ALPO Comets Section received 48 images and/or sketches from Dan Bartlett, Michel Deconinck, Christian Harder, Gianluca Masi, Martin Mobberley, Mike Olason, and Uwe Pilz and 91 visual and CCD magnitude measurements from Michel Deconinck, J. J. Gonzalez, Mike Olason, and Chris Wyatt of the following comets: C/2021 O1 (Nishimura), P/2021 N2 (Fuls), P/2021 N1 (ZTF), P/2021 L2 (Leonard), C/2020 T2 (Palomar), C/2020 S3 (Erasmus), C/2020 PV6 (PANSTARRS), C/2020 K6 (Rankin), C/2020 K1 (PANSTARRS), C/2020 J1 (SONEAR), C/2020 F5 (MASTER), C/2019 U5 (PANSTARRS), C/2019 L3 (ATLAS), C/2019 K7 (Smith), C/2019 F1 (ATLAS-Africano), C/2018 U1 (Lemmon), C/2017 U7 (PANSTARRS), C/2017 K2 (PANSTARRS), 424P/La Sagra, 402P/LINEAR, 395P/Catalina-NEAT, 378P/McNaught, 284P/McNaught, 252P/LINEAR, 246P/NEAT, 241P/LINEAR, 193P/LINEAR-NEAT, 132P/Helin-Roman-Alu, 119P/Parker-Hartley, 110P/Hartley, 108P/Ciffreo, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 19P/Borrelly, 17P/Holmes, 15P/Finlay, 10P/Tempel, 7P/Pons-Winnecke, 6P/d’Arrest, and 4P/Faye.

We’d like to especially thank Dan Bartlett who has graciously agreed to contribute his observations to the ALPO Comets Section.

In addition to observations submitted directly to the ALPO, we occasionally use data from other sources to augment our analysis. We would like to acknowledge with thanks observations submitted directly to the ALPO as well as those originally submitted to the International Comet Quarterly, Minor Planet Center, and COBS Comet Observation Database. We would also like to thank the Jet Propulsion Laboratory for making available their Small-Body Browser and Orbit Visualizer and Seiichi Yoshida for his Comets for Windows programs that is used to produce the lightcurves in these pages. And last but not least, we’d like to thank Syuichi Nakano and the Minor Planet Center for their comet orbital elements, , the asteroid surveys for their discoveries, and all of the observers who volunteer their time to adding to our knowledge of these amazing objects.

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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