Comet Section        


April 3, 2022 – ALPO Comet News for April 2022


The big comet question for this month is what’s up with C/2021 O3 (PANSTARRS)? Arriving at perihelion on April 21 at a small heliocentric distance of 0.29 au, some predictions have PANSTARRS peaking at 4-5th magnitude. Unfortunately, the comet has a lot working against it. It is intrinsically faint, likely making its first passage through the inner Solar System, and when last observed back in early February was brightening at a very slow rate. All of these point to a comet that may be prone to disintegration as it nears perihelion, if it hasn’t already. Since the comet has been located a small solar elongation over the past 2 months, we don’t really know how bright it currently is. And to make things worse, it will either be unobservable or only observable deep in twilight in April.

Don’t worry if C/2021 O3 disappoints as there are plenty of other comets observable between 9th and 13th magnitude this month. C/2019 L3 (ATLAS) is at 9th magnitude and well placed in the evening sky. C/2017 K2 (PANSTARRS) continues to slowly brighten and may break the magnitude 10 level in the morning sky. Last month’s brightest comet, C/2021 F1 (Lemmon-PANSTARRS), will still be around 8th magnitude but will be too close to the Sun for most observers. Unfortunately, another 9th magnitude comet, 45P/Honda-Mrkos-Pajdusáková, will also be too close to the Sun for observation in April.

On the fainter side (between magnitude 10 and 13) we have short-period comets 9P/Tempel, 19P/Borrelly, 22P/Kopff, 29P/Schwassmann-Wachmann, 67P/Churyumov-Gerasimenko, 104P/Kowal, C/2019 T4 (ATLAS), C/2020 (ZTF), C/2021 E3 (ZTF), and C/2021 P4 (ATLAS). A few months ago, C/2021 A1 (Leonard) was dazzling comet watchers. The comet may be in the midst of its own disintegration or in the process of “turning off”. Imagers are encouraged to watch as the dusty remnant of Leonard slowly disperses.

Looking ahead to next year, recently discovered C/2022 E3 (ZTF) is currently 16th magnitude but may brighten to 5-6th magnitude next January and February.

Since the last Report was published on February 23, the ALPO Comets Section has received 161 magnitude estimates and 48 images and sketches of comets C/2021 P4 (ATLAS), C/2021 F1 (Lemmon-PANSTARRS), C/2021 E3 (ZTF), C/2020 Y2 (ATLAS), C/2020 V2 (ZTF), C/2020 U5 (PANSTARRS), C/2020 M5 (ATLAS), C/2020 J1 (SONEAR), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 116P/Wild, 108P/Ciffreo, 104P/Kowal, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 22P/Kopff, 19P/Borrelly, and 9P/Tempel. Observations were contributed by Dan Bartlett, Michel Deconinck, Stephane Ferier, J. J. Gonzalez, Christian Harder, Eliot Herman, Martin Mobberley, Uwe Pilz, Raymond Ramlow, Tenho Tuomi, and Chris Wyatt.

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 are used to produce the lightcurves and orbit diagrams in these pages. And last but not least, we’d like to thank Syuichi Nakano and the Minor Planet Center for their comet orbit elements, the asteroid surveys and dedicated comet hunters 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.

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