Comet Section        

 
 

June 7, 2022 – ALPO Comet News for June 2022

Summary

To borrow from Mark Twain, the reports of C/2021 O3 (PANSTARRS)’s demise was an exaggeration. The comet is much fainter than hoped for at 12th magnitude but well placed for northern observers. While C/2021 O3 did not become the bright object we expected, another comet, 45P/Honda-Mrkos-Pajdusakova, is running about 3 magnitudes brighter than expected (starting around 8th magnitude and fading to 10th this month) low in the evening sky. Two other comets will be brighter than 10th magnitude in June, C/2021 E3 (ZTF0 but only observable from the southern hemisphere, and C/2017 K2 (PANSTARRS) which is visible to all. In the magnitude 10 to 13 range are no less than 9 comets, 19P/Borrelly, 22P/Kopff, 169P/NEAT, C/2019 L3 (ATLAS), C/2019 T4 (ATLAS), C/2020 V2 (ZTF), C/2021 E3 (ZTF). C/2021 F1 (Lemmon-PANSTARRS), and C/2021 P4 (PANSTARRS).

In May the ALPO Comets Section received 76 magnitude estimates and 69 images/sketches of comets C/2021 P4 (ATLAS), C/2021 O3 (PANSTARRS), C/2021 E3 (ZTF), C/2021 A1 (Leonard), C/2020 Y2 (ATLAS), C/2020 V2 (ZTF), C/2020 R7 (ATLAS), C/2020 M5 (ATLAS), C/2020 K1 (PANSTARRS), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 274P/Tombaugh-Tenagra, 272P/NEAT, 254P/McNaught, 244P/Scotti, 117P/Helin-Roman-Alu, 116P/Wild, 104P/Kowal, 73P/Schwassmann-Wachmann, 67P/Churyumov-Gerasimenko, 45P/Honda-Mrkos-Pajdusakova, 22P/Kopff, 19P/Borrelly, and 9P/Tempel. A hearty thanks to our April contributors: Dan Bartlett, Michel Deconinck, J. J. Gonzalez, Christian Harder, Michael Jager, Martin Mobberley, Mike Olason, 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.

 
 

May 2, 2022 – ALPO Comet News for May 2022

Summary

Last month’s big question was “What’s up with C/2021 O3 (PANSTARRS)?” Would it survive passing 0.29 au from the Sun or disintegrate like many other dynamically new, intrinsically faint comets? We now have our answer. C/2021 O3 has likely disintegrated with a remnant dust cloud being all that’s remains of the comet. Still as of the end of April, some ground-based observers have been able to detect a diffuse remnant at ~9th magnitude. This at least gives us some hope of being able to monitor the slow dispersal of the dusty remains as it heads into the northern circumpolar evening sky.

Of course, C/2021 O3 isn’t the only comet in the sky. While May won’t see any very bright comets, a number will be in the 9-10th magnitude range including C/2017 K2 (PANSTARRS), C/2019 L3 (ATLAS), C/2021 E3 (ZTF), and C/2021 F1 (Lemmon-PANSTARRS) (the last two only visible from the southern hemisphere). Observers who can push fainter to around 12th magnitude can also observe 9P/Tempel, 19P/Borrelly, 22P/Kopff, 45P/Honda-Mrkos-Pajdusáková, C/2019 T4 (ATLAS), C/2020 (ZTF), and C/2021 P4 (ATLAS).

April saw the ALPO Comets Section receive 89 magnitude estimates and 15 images/sketches of comets C/2021 P4 (ATLAS), C/2021 O3 (PANSTARRS), C/2021 E3 (ZTF), C/2021 A1 (Leonard), C/2020 Y2 (ATLAS), C/2020 V2 (ZTF), C/2020 M5 (ATLAS), C/2020 K1 (PANSTARRS), C/2020 J1 (SONEAR), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 116P/Wild, 104P/Kowal, 73P/Schwassmann-Wachmann, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 22P/Kopff, 19P/Borrelly, and 9P/Tempel. A hearty thanks to our April contributors: Dan Bartlett, Michel Deconinck, J. J. Gonzalez, Christian Harder, Michael Jager, Mike Olason, Uwe Pilz, Raymond Ramlow, Chris Schur, 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.

 
 

April 3, 2022 – ALPO Comet News for April 2022

Summary

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.

 
 

February 23, 2022 – ALPO Comet News for February-March 2022

Summary

Well, this Comet News is either very late for February or a few days early for March. Due to delays in getting this out for February, it will cover the remainder of February and all of March.

A large number of comets are in the 8th-10th magnitude range including 19P/Borrelly, 67P/Churyumov-Gerasimenko, 104P/Kowal, and C/2019 L3 (PANSTARRS) in the evening and C/2017 K2 (PANSTARRS) and C/2021 F1 (Lemmon-PANSTARRS) in the morning sky. On a bit of the fainter side are receding 4P/Faye and 6P/d’Arrest, incoming C/2019 T4 (ATLAS) and C/2021 E3 (ZTF), and two short-period comets at perihelion 9P/Tempel and 22P/Kopff. After spending a few weeks too close to the Sun for observation, last year’s comet highlight, C/2021 A1 (Leonard), should reappear as a fainter object of ~11-12th magnitude but only for observers in the southern hemisphere.

Since January 1, the ALPO Comets Section has received 111 magnitude estimates and 61 images and sketches of comets C/2022 A1 (Sárneczky), C/2021 O3 (PANSTARRS), C/2021 F1 (Lemmon-PANSTARRS), C/2021 A1 (Leonard), C/2020 V2 (ZTF), C/2019 U5 (PANSTARRS), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), C/2017 K2 (PANSTARRS), 430P/Scotti, 116P/Wild, 104P/Kowal, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 19P/Borrelly, 6P/d’Arrest and 4P/Faye. Observations were contributed by Paul G. Abel, Dan Bartlett, Michel Besson, Denis Buczynski, John Chumack, Michel Deconinck, Lukas Demetz, J. J. Gonzalez, Christian Harder, Jan Hattenbach, Carl Hergenrother, Eliot Herman, Michael Jäger, Gianluca Masi, Martin Mobberley, Michael Olason, Uwe Pilz, Ludovic Prebet, 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.

- Carl Hergenrother

 
 

January 3, 2022 – ALPO Comet News for January 2022

Summary

After a year of “will it, won’t it”, C/2021 A1 (Leonard) developed into the best comet of 2021. While a difficult object to observe when at its brightest due to a small solar elongation, several outbursts resulted in a peak brightness between magnitude 2.5 and 3.0. As the year begins, the comet has faded to around magnitude 5.0. The comet remains very dynamic with imagers following nightly changes in its coma and tail. Speaking of tails, some images are showing a tail nearly 40 deg in length! Northern observers will only have a few more days to observe Leonard while southern hemisphere observers should be able to follow Leonard throughout the month.

Leonard may be the brightest comet out there, but it isn’t the only one in the range of modest backyard equipment. 19P/Borrelly is around 8-9th magnitude in the evening sky. 67P/Churyumov-Gerasimenko and C/2019 L3 (ATLAS) are also at a similar brightness near opposition. Slightly fainter comets (magnitude 10-11) include 6P/d’Arrest, 104P/Kowal, and C/2017 K2 (PANSTARRS).

Since December 1, the ALPO Comets Section has received 118 magnitude estimates and 120 images and sketches of comets C/2021 A1 (Leonard), C/2019 T4 (ATLAS), C/2019 L3 (ATLAS), 104P/Kowal, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 19P/Borrelly, 6P/d’Arrest, and 4P/Faye. Observations were contributed by Michael Amato, Salvador Aguirre, Dan Bartlett, Michel Deconinck, Lukas Demetz, Walter Elias, J. J. Gonzalez, Christian Harder, Jan Hattenbach, Carl Hergenrother, Eliot Herman, Michael Jäger, Kardasis Manos, Luis Alberto Mansilla, Frank McCague, Martin Mobberley, Michael Olason , Uwe Pilz, Olivier Planchon, Efrain Morales Rivera, Michael Rosolina, Gregg Ruppel, Chris Schur, Leandro Sid, Willian Souza, Tenho Tuomi, Jim Twellman, Chris Wyatt, and Skygems Observatory.

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

 
 

December 3, 2021 – ALPO Comet News for December 2021

Summary

It is now or never for C/2021 A1 (Leonard). Currently magnitude 6.5, Leonard has the potential to become a few magnitudes brighter as it passes 0.23 au from Earth on December 12. Complicating any forecast of how bright or observable it might get are a very low solar elongation (down to 15 degrees), uncertainty in the effect of dust forward scattering to enhance Leonard’s brightness, and signs that the comet is fading or perhaps even breaking up. This is an object well worth watching in the morning sky from the northern hemisphere during the first half of the month and in the evening sky during the second half of December (though at that time it will be much easier to observe from the southern hemisphere).

Other comets brighter than 10th magnitude in December include C/2019 L3 (ATLAS), 19P/Borrelly, and 67P/Churyumov-Gerasimenko.

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

 
 

November 7, 2021 – ALPO Comet News for November 2021

Summary

After an exciting 2020 for comets, 2021 seemed to be a bit of a letdown. Well, it may have taken most of the year to get going, but 2021 is finally picking up steam. We now have three comets brighter than magnitude 10. C/2021 A1 (Leonard) may brighten to the verge of naked eye visibility (for those under very dark skies) by the end of the month. It should get even brighter next month when it could reach 4th magnitude or perhaps even brighter. C/2019 L3 (PANSTARRS) and 67P/Churyumov-Gerasimenko will be around magnitude 9 this month.

If you’ve never observed 29P/Schwassmann-Wachmann before, this is a great time to start. The Centaur comet has experienced a succession of outbursts since late September. As a result, it is brighter than it’s been in years with visual observers placing it between magnitude 10 and 11.

Two recently discovered comets have the potential to be nice small telescope objects when they arrive at perihelion over the next few years. C/2021 S3 (PANSTARRS) may reach 8th magnitude in 2024 while C/2021 T4 (Lemmon) could be a 9th magnitude object in 2023.

Comets Section News

From October 1 through the first week of November, the ALPO Comets Section received 125 visual and CCD magnitude measurements and 80 images and/or sketches from Dan Bartlett, Michel Besson, Denis Buczynski, Dan Crowson, Michel Deconinck, J. J. Gonzalez, Christian Harder, Carl Hergenrother, Eliot Herman, Gianluca Masi, Martin Mobberley, Mike Olason, Ludovic Prebet, Efrain Morales Rivera, Chris Schur, Tenho Tuomi, Dennis Wilde, and Chris Wyatt of the following comets: C/2021 K1 (ATLAS), C/2021 A1 (Leonard), C/2020 T2 (Palomar), C/2020 F5 (MASTER), C/2019 T4 (ATLAS), C/2019 LD2 (ATLAS), C/2019 L3 (ATLAS), C/2019 F1 (ATLAS-Africano), C/2017 K2 (PANSTARRS), 433P/(248370) 2005 QN173 ,429P/LINEAR-Hill, 424P/La Sagra, 284P/McNaught, 246P/NEAT, 230P/LINEAR, 179P/Jedicke, 132P/Helin-Roman-Alu, 119P/Parker-Hartley, 113P/Spitaler, 104P/Kowal, 97P/Metcalf-Brewington, 94P/Russell, 67P/Churyumov- Gerasimenko, 57P/du Toit-Neujmin-Delporte, 29P/Schwassmann-Wachmann, 19P/Borrelly, 8P/Tuttle, 7P/Pons-Winnecke, 6P/d’Arrest, and 4P/Faye.

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

 
 

October 4, 2021 – ALPO Comet News for October 2021

Summary

Magnitude 9 to 10 may not be everyone’s idea of “bright” when it comes to comets. After months of no comets getting brighter than 10th magnitude, we finally have a few objects breaking the 10th magnitude barrier. The target of the European Space Agency’s Rosetta mission, 67P/Churyumov-Gerasimenko may brighten to around magnitude 9 this month. It will be observable from both hemispheres in the morning sky. 8P/Tuttle will start the month around 8-9th magnitude but is limited to southern hemisphere observers. C/2019 L3 (PANSTARRS) could become brighter than magnitude 10 though it will mainly be a northern object.

29P/Schwassmann-Wachmann experienced 4 outbursts in quick succession in late September. As a result, it is brighter than it has become in years with visual observers placing it between magnitude 10 and 11.

We continue to watch C/2021 A1 (Leonard) develop as it heads towards a December encounter with Earth. Recent observations show a rapid brightening trend, so imagers and large aperture visual observers are encouraged to observe it this month as it may brighten to magnitude 11 by the end of the month.

Comets Section News

During September, the ALPO Comets Section received 51 images and/or sketches from Dan Bartlett, Denis Buczynski, Eliot Herman, Gianluca Masi, Martin Mobberley, Uwe Pilz, Efrain Morales Rivera, Gregg Ruppel, and Chris Schur and 67 visual and CCD magnitude measurements from Michel Deconinck, J. J. Gonzalez, Mike Olason, and Chris Wyatt of the following comets: P/2021 Q5 (ATLAS), C/2021 O3 (PANSTARRS), C/2021 A1 (Leonard), C/2020 T2 (Palomar), C/2020 PV6 (PANSTARRS), C/2020 F5 (MASTER), C/2019 O3 (PANSTARRS), C/2019 L3 (ATLAS), C/2019 F1 (ATLAS-Africano), C/2018 U1 (Lemmon), C/2020 T2 (PANSTARRS), C/2017 K2 (PANSTARRS), 284P/McNaught, 193P/LINEAR-NEAT, 106P/Schuster, 67P/Churyumov-Gerasimenko, 29P/Schwassmann-Wachmann, 19P/Borrelly, 15P/Finlay, 8P/Tuttle, 7P/Pons-Winnecke, 6P/d’Arrest, and 4P/Faye.

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 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.

- Carl Hergenrother

 
 

September 6, 2021 – ALPO Comet News for September 2021

Summary

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

 
 

August 5, 2021 – ALPO Comet News for August 2021

Summary

July saw the discovery of 9th magnitude C/2021 O1 (Nishimura), though the comet was located so close to the Sun that few have been able to observe it. While we are still waiting for a comet to brighten into an easy-to-observe object for small apertures, a number of fainter comets are visible in the magnitude 10-13 range for imagers and large aperture visual observers. A recent discovery, C/2021 O3 (PANSTARRS), is currently around 18-19th magnitude but may brighten into a nice binocular object early next year.

Comets Section News

The ALPO’s Annual Conference will be held virtually on Friday and Saturday, August 13-14. Each day is packed with talks about various aspects of Solar System observing. The Comets Section will be presenting two talks. One will be an overview of the past year’s comet observations. The second talk will be on a slightly different topic, Solar System numismatics (i.e., Solar System objects, including comets, on coins and medals). The meeting is free and more information on the conference and how to watch can be found on the ALPO web site at http://alpo-astronomy.org/.

During July, the ALPO Comets Section received 27 images and/or sketches from Michel Deconinck, Carl Hergenrother, Martin, Mobberley, and Mike Olason of the following comets: 4P/Faye, 7P/Pons-Winnecke, 10P/Tempel, 15P/Finlay, 19P/Borrelly, 47P/Ashbrook-Jackson, 106P/Schuster, C/2017 K2 (PANSTARRS), C/2017 Y2 (PANSTARRS), C/2018 U1 (Lemmon), C/2019 K7 (Smith), C/2019 T3 (ATLAS), C/2019 T4 (ATLAS), C/2019 U5 (PANSTARRS), C/2020 F2 (ATLAS), C/2020 H5 (Robinson), C/2020 K1 (PANSTARRS), C/2020 M5 (ATLAS), C/2020 O2 (Amaral), C/2020 PV6 (PANSTARRS), C/2020 T2 (Palomar), C/2021 A1 (Leonard), C/2021 O1 (Nishimura).

The Section also received 82 visual and CCD magnitude measurements from Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, Mike Olason, and Chris Wyatt of comets 4P/Faye, 7P/Pons-Winnecke, 10P/Tempel, 15P/Finlay, 19P/Borrelly, 67P/Churyumov-Gerasimenko, 106P/Schuster, 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 PV6 (PANSTARRS), C/2020 T2 (Palomar), C/2021 A1 (Leonard), and C/2021 O1 (Nishimura).

In addition to observations submitted to the ALPO, we also occasionally use data from other sources to augment our analysis. We acknowledge with thanks comet observations submitted to the International Comet Quarterly, Minor Planet Center, 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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