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ALPO Comet News for December 2020

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#1 Carl H.

Carl H.

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Posted 03 December 2020 - 02:45 AM

ALPO COMET NEWS FOR DECEMBER 2020
A Publication of the Comets Section of the Association of Lunar and Planetary Observers
By Carl Hergenrother

 

The monthly Association of Lunar and Planetary Observers (ALPO) Comet News PDF can be found on the ALPO Comets Section website @ http://www.alpo-astr....org/cometblog/. A shorter version of this report is posted here (minus magnitude estimates and figures). The ALPO Comet Section welcomes all comet related observations, whether textual descriptions, images, drawings, magnitude estimates, or spectra. You do not have to be a member of ALPO to submit material, though membership is encouraged. To learn more about the ALPO, please visit us @ http://www.alpo-astronomy.org.

 

November turned out to be a great month for comet observers with 101 magnitude estimates of 9 comets and 44 images of 10 comets being submitted to the Comets Section. C/2020 S3 (Erasmus) led the pack as it brightened to 6th magnitude. C/2020 M3 (ATLAS), 156P/Russell-LINEAR and 88P/Howell were also visible between 7th and 10th magnitude. This month, Erasmus will be too close to the Sun for ground-based observers. As is fitting for 2020, we will be able to follow Erasmus virtually in images taken by the SOHO and STEREO spacecraft. C/2020 M3, 156P, and 88P will be fading but still bright enough for small aperture observers. For those willing to try fainter objects, 11P/Tempel-Swift-LINEAR, 29P/Schwassmann-Wachmann, 141P/Machholz, 398P/Boattini, and disintegrating C/2020 P1 (NEOWISE) will be between 10th and 14th magnitude.

 

Bright Comets (magnitude < 10.0)
C/2020 S3 (Erasmus) – Comet C/2020 S3 (Erasmus) is a dynamically old long-period comet with an orbital period on the order of ~2600 years. Though a faint 17th magnitude object at discovery back on 2020 September 17 with the ATLAS 0.5-m f/2 Schmidt at Mauna Loa, the comet rapidly brightened to around magnitude 10.0 by the end of October.

 

On November 2, Chris Wyatt found the comet to be at magnitude 10.2. For the next week, the Moon was a problem and there were few observations. Finally, on the morning of November 11, I attempted to reobserve Erasmus. Imagine my surprise when I swept up a bright condensed 7th magnitude object instead of the 8-9th magnitude diffuse fuzzball that I was expecting. With Erasmus as bright as magnitude 7.4 on the 11th, there was some excitement as it should have brightened even more as it rapidly moved closer to the Sun. Unfortunately, the comet seemed to be stuck in neutral and stayed between magnitude 7.0 and 7.5 till the end of November when it finally started to brighten again with Willian Souza placing it at magnitude 6.6-6.7 on the 29th.

 

Erasmus was very well observed with the Comets Section receiving 39 magnitude estimates and 14 images/sketches from Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, Martin Mobberley, Ludovic Perbet, Michael Rosolina, Gregg Ruppel, Willian Souza, Chris Schur, Richard Tyson, Kacper Wierzchos, and Chris Wyatt. All observers reported the comet as small (3’-5’ coma) and strongly condensed (DC = 5-7.5). A tail up to 1.4 degrees in length in the anti-solar direction was observed as well.

 

So now the bad news, if you haven’t seen Erasmus you are probably out of luck. The comet starts December at an elongation of only 26 degrees and only rises after the start of astronomical twilight in the morning sky. Conditions only get worse as the comet approaches a minimum elongation of 5.2 degrees on December 24 as it passes on the far side of the Sun. Even though the comet could be a 5th magnitude object around the time of perihelion on December 12 (q = 0.40 au), it will be invisible to ground-based observers. Luckily the comet will be visible in data taken with the SOHO and STEREO-A spacecraft. Erasmus has been visible in the STEREO-A HI-1 FOV since November 13. On November 29 it displayed a 1.3-degree long tail. It should become visible in the SOHO C3 coronagraph FOV for about 2 weeks centered on December 24. Unfortunately, ground-based observers won’t be able to see Erasmus again till April 2021 when it should be too faint for visual observation.

 

C/2020 S3 (Erasmus)

T = 2020-Dec-12  q = 0.40 au                                      Max El
Long-Period comet – dynamically old                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01   6.5   14 34  -23 25   0.497   1.114    26    Lib     1    0
2020-12-06   6.0   15 22  -23 35   0.430   1.183    20    Lib     0    0 
2020-12-11   5.8   16 10  -22 54   0.395   1.264    14    Sco     0    0 
2020-12-16   6.0   16 56  -21 35   0.406   1.347     9    Oph     0    0
2020-12-21   6.7   17 39  -19 50   0.458   1.427     5    Oph     0    0
2020-12-26   7.5   18 17  -17 54   0.536   1.506     5    Sgr     0    0
2020-12-31   8.3   18 51  -15 55   0.626   1.587     7    Sgr     0    0
2021-01-05   9.0   19 20  -13 56   0.721   1.672     9    Sct     0    0
            Comet Magnitude Parameters --- H = 9.3, 2.5n = 10.0

 

C/2020 M3 (ATLAS) – C/2020 M3 (ATLAS) provided quite the visual contrast to C/2020 S3 (Erasmus). While Erasmus was small and strongly condensed, ATLAS was larger and more diffuse. Even though both comets were 7th magnitude objects in November, ATLAS was significantly more difficult to observe.

 

Like Erasmus, ATLAS is a dynamically old object though with an even shorter orbital period of 139 years. Also like Erasmus, ATLAS was faint at discovery (19th magnitude on 2020 June 27) and rapidly brightened to within visual range. The ALPO received 31 magnitude estimates and 15 images/sketches from Denis Buczynski, Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, Gabriel Jaimes, Martin Mobberley, Ludovic Perbet, Olivier Planchon, Michael Rosolina, Chris Schur, Willian Souza, Kacper Wierzchos, and Chris Wyatt. Though past perihelion, the comet seemed to hold its brightness (between magnitude 7.5 and 8.0) for most of the month. Its coma was measured between 1’ and 15’. The large range in coma diameters highlights how sensitive the observability of a large diffuse coma (DC = 2-4) is to sky conditions, aperture, and magnification.  

 

This month C/2020 M3 is better placed for northern observers in the evening sky in Taurus (Dec 1-4), Auriga (4-31). Now over a month past its October 27 perihelion at 1.27 au and closest approach to Earth at 0.36 au on November 14, the comet is in full retreat from both the Sun and Earth. Starting the month slightly fainter than magnitude 8, the comet could be around magnitude 10 by the end of the year depending on its rate of fading.

 

C/2020 M3 (ATLAS)

T = 2020-Oct-25  q = 1.27 au                                      Max El
Halley-type comet – 139-year period                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01   8.2   05 25  +25 25   1.378   0.399   166    Tau    76   24
2020-12-06   8.4   05 23  +30 33   1.408   0.428   169    Aur    81   19
2020-12-11   8.7   05 20  +34 53   1.441   0.463   167    Aur    85   15
2020-12-16   9.0   05 18  +38 26   1.476   0.504   164    Aur    89   11
2020-12-21   9.3   05 16  +41 17   1.514   0.551   160    Aur    89    9
2020-12-26   9.6   05 14  +43 29   1.553   0.603   155    Aur    86    6
2020-12-31   9.9   05 14  +45 11   1.595   0.660   151    Aur    85    5
2021-01-05  10.2   05 14  +46 27   1.638   0.721   147    Aur    83    3
            Comet Magnitude Parameters --- H = 8.8, 2.5n = 10.0

 

88P/Howell – Jupiter-family comet 88P/Howell is now outbound after a September 28 perihelion at 1.35 au. Visual observations by J. J. Gonzalez, Carl Hergenrother and Chris Wyatt found 88P between magnitude 8.9 and 9.4 in November. The comet should fade from around magnitude 9.6 to 10.4 this month as it moves through Capricornus (Dec 1-26) and Aquarius (26-31) in the evening sky. Comet Howell is next at perihelion in March 2026 when it may peak at ~9.5.

 

88P/Howell

T = 2020-Sep-28  q = 1.35 au                                      Max El
Jupiter-family comet                                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01   9.6   20 40  -22 07   1.529   1.809    57    Cap    21   24
2020-12-06   9.8   20 57  -20 57   1.554   1.859    56    Cap    22   21
2020-12-11   9.9   21 13  -19 43   1.580   1.911    55    Cap    23   19
2020-12-16  10.0   21 28  -18 25   1.607   1.966    54    Cap    23   16
2020-12-21  10.2   21 43  -17 06   1.635   2.023    53    Cap    23   14
2020-12-26  10.3   21 58  -15 44   1.664   2.082    51    Cap    24   12
2020-12-31  10.4   22 12  -14 21   1.694   2.142    50    Aqr    24   10
2021-01-05  10.6   22 26  -12 58   1.724   2.203    48    Aqr    23    8
            Comet Magnitude Parameters --- H = 6.5, 2.5n = 10.0

 

156P/Russell-LINEAR – 156P was first observed by Kenneth Russell on a single 90-min photographic plate taken by F. G. Watson with the U.K. Schmidt Telescope at Siding Spring Observatory on 1986 September 3. Further attempts to image the comet in 1986 were unsuccessful at that time. Fast forwarding to 2000, asteroidal LINEAR discovery 2000 QD181 was linked with another LINEAR discovery, 2000 XV43, and photographic Shoemaker discovery 1993 WU. With the updated orbit, an additional photographic image from one of the 1986 follow-up plates was identified. In addition to being seen in 1986, 1993, and 2000, 156P was also seen in 2007 and 2014. Though observed as cometary in the 1986 discovery image, most observations reported no cometary activity.

 

For an object that rarely shows cometary activity, it has been quite a surprise to observe this comet in small apertures as a 9-10th magnitude object. Michel Delconinck, J. J. Gonzalez, Carl Hergenrother, Kacper Wierzchos, and Chris Wyatt observed 156P between magnitude 9.6 and 11.0 in November. The perceived brightness of the comet has proven to be very sensitive to the equipment used. This is also obvious from the large scatter in DC values (3-6) and coma diameters (3’-8’). CCD images hint at the problem. 156P has a small condensed dusty inner coma within a much large diffuse gas coma.

 

156P is now a few weeks passed its 2020 November 17 perihelion at 1.33 au and over a month from its 0.48 au close approach with Earth. The comet should start to fade as it moves through evening constellations of Pisces (Dec 1-22), Andromeda (22-26), and back into Pisces (26-31).

 

156P/Russell-LINEAR

T = 2020-Nov-17  q = 1.33 au                                      Max El
Jupiter-family comet – 6.43-year period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01   9.9   00 03  +08 34   1.342   0.584   115    Psc    59   36
2020-12-06  10.0   00 12  +12 00   1.350   0.612   113    Psc    62   31
2020-12-11  10.2   00 22  +15 14   1.360   0.644   111    Psc    65   26
2020-12-16  10.4   00 33  +18 15   1.373   0.678   110    Psc    68   22
2020-12-21  10.5   00 44  +21 03   1.388   0.715   108    Psc    71   18
2020-12-26  10.7   00 56  +23 37   1.405   0.755   107    And    74   15
2020-12-31  10.8   01 09  +25 59   1.424   0.797   105    Psc    76   12
2021-01-05  11.0   01 22  +28 08   1.444   0.842   104    Psc    78    9
            Comet Magnitude Parameters --- H = 10.0, 2.5n = 10.0

 

Fainter Comets of Interest (generally fainter than magnitude 10.0)

11P/Tempel-Swift-LINEAR – I have to admit, that I really enjoy researching the back stories of comets like 11P/Tempel-Swift-LINEAR which was discovered, then lost, then rediscovered, then lost, then re-discovered yet again. As a former comet hunter, I’m a bit envious of those who re-discovered these long-lost comets and now get to have their name share a comet with some of the illustrious hunters of the past. Though as you’ll see below, I did get to play a small part in 11P’s saga.

 

Ernst Wilhelm Leberecht Tempel of Marseilles, France visually swept up 11P for the first time on 1869 November 27. Tempel discovered or co-discovered 21 comets including 9P/Tempel, the target of both the Deep Impact and Stardust-NEXT spacecraft missions, and 55P/Tempel-Tuttle, the parent of the Leonid meteor shower. During the 1869 apparition, the comet passed within 0.25 au of Earth and peaked at 8th magnitude.

 

After passing unseen in 1875, 11P was re-discovered on 1880 October 11 by Lewis Swift of Rochester, New York. Swift was also a prolific visual comet hunter with 13 discoveries including 109P/Swift -Tuttle, the parent of the Perseids. The comet passed even closer to the Earth during this return (0.13 au) and brightened to 7th magnitude. The comet was seen in 1891 (when it passed 0.24 au from Earth and reached 10th magnitude) and 1908 (passed 0.63 au from Earth and peaked at 12th magnitude), but missed at poorly placed apparitions in 1886, 1897, and 1903.

 

After going unseen for 93 years, the P/Tempel-Swift was re-discovered for the third time on December 2001 by the LINEAR survey at 19th magnitude. This is where my small part of 11P’s story comes in as I was one of the two people to initially suggest the new LINEAR comet was a return of Tempel-Swift. Though 11P brightened to 17th magnitude in 2001, it was much fainter than at its returns in the 1800s. The intrinsic fading could be a result of a large increase in perihelion distance from 1.06 au in 1869, 1.09 au 1891, and 1.15 au in 1908 to 1.58 au in 2001. After a close approach to Jupiter in September 2018 (0.60 au), 11P’s perihelion has dropped back down to 1.39 au. The lower perihelion on 2020 November 26 and minimum comet-Earth distance of 0.49 au on November 3 have resulted in 11P reaching its brightest observed magnitude in over a century.

 

CCD imagers have been watched this comet rapidly brighten from magnitude 17 in mid-September to around 13.5 in November. Interestingly, both J. J. Gonzalez and Michel Deconinck have visually estimated the comet to be even brighter at around magnitude 11.3 to 11.6. These observations were made on November 22 and 23. The brightness forecast below is very uncertain as the rate of brightening is extreme and also does not do a good job of modeling the actual brightness data. This month, 11P is an evening object moving through Pisces (Dec 1-28) and Cetus (28-31) and should fade as it is now past perihelion and closest approach to Earth.

 

11P/Tempel-Swift-LINEAR

T = 2020-Nov-22  q = 1.39 au                                      Max El
Jupiter-family comet – 5.95-year period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01  13.3   00 52  +11 22   1.390   0.550   127    Psc    61   37
2020-12-06  13.4   01 05  +10 02   1.393   0.572   124    Psc    60   37
2020-12-11  13.8   01 19  +08 55   1.398   0.597   122    Psc    59   38
2020-12-16  14.0   01 32  +08 00   1.406   0.625   120    Psc    58   37
2020-12-21  14.3   01 46  +07 17   1.416   0.656   117    Psc    57   37
2020-12-26  14.7   02 00  +06 46   1.427   0.691   115    Psc    57   37
2020-12-31  15.1   02 14  +06 24   1.441   0.729   113    Cet    56   37
2021-01-05  15.5   02 28  +06 12   1.456   0.769   111    Cet    56   36
            Comet Magnitude Parameters --- H = 5.1, 2.5n = 67.1

 

29P/Schwassmann-Wachmann - 29P/Schwassmann-Wachmann was discovered photographically in 1927 by German astronomer team Arnold Schwassmann and Arno Arthur Wachmann. The duo discovered 4 comets together, three short-period comets (29P, 31P and 73P) and a long-period comet shared with Leslie Peltier (C/1930 D1).

 

On November 19, 29P underwent another of its frequent outbursts and is currently around 12th magnitude in the evening sky in Aries. If you image 29P, please consider contributing to the British Astronomical Society’s (BAA) 29P monitoring program coordinated by Richard Miles. You can find more information at the BAA’s “Observing the outbursting comet 29P/Schwassmann-Wachmann” page ( https://britastro.org/node/18562 ).

 

29P/Schwassmann-Wachmann

T = 2019-Mar-07  q = 5.77 au                                     Max El
Centaur comet - 14.8-yr orbital period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-12-01  12-13  02 21  +25 42   5.840   4.962   150    Ari    76   24 
2020-12-06  12-13  02 19  +25 27   5.841   5.004   145    Ari    76   24
2020-12-11  12-13  02 18  +25 14   5.842   5.052   140    Ari    75   24
2020-12-16  12-13  02 16  +25 00   5.844   5.106   134    Ari    75   24
2020-12-21  12-13  02 15  +24 48   5.845   5.166   129    Ari    75   23
2020-12-26  12-13  02 15  +24 36   5.846   5.230   124    Ari    75   22
2020-12-31  12-13  02 15  +24 26   5.847   5.298   119    Ari    75   20
2021-01-05  12-13  02 15  +24 17   5.848   5.370   114    Ari    74   19

 

141P/Machholz - Former ALPO Comet Section Coordinator Don Machholz discovered this Jupiter-family comet in 1994. With a 5.34-year period, 141P is making its 5th observed perihelion passage. During 1994 the comet was actually a multiple comet with 5 components (component D was even observed to split during the apparition). The two brightest components (the primary A and secondary D) made a visually striking double comet in small telescopes. Components A and D were re-observed in 1999 but by 2005 only component A was visible. Due to poor observing conditions, no components were seen in 2010. During the last return in 2015, the primary (A) has been seen as well as another component (H) which could have been a new sighting of components B or C observed back in 1994.

 

141P’s split personalities didn’t begin in 1994. Research by Zdenek Sekanina found that components B through E split from the primary during the period of 1987 to 1991. Other research suggests 141P (or its progenitor) may have been breaking up for some time as it is related to both the Alpha Capricornid meteor shower and comet 169P/NEAT (a weakly active comet on an orbit with a 4.2-year period).

 

So far, the only observations of this comet were made back August when it was still a very faint 21st magnitude. Since then, I have seen no published observations of 141P even though the comet should be rapidly brightening as it approaches perihelion on December 16 at 0.81 au and close approach to Earth on January 19 at 0.53 au. It will be interesting to see how bright this comet gets and whether any additional components are observed. 141P is an evening object moving through Aquileia (Dec 1), Capricornus (1-9), Aquarius (9-19), Capricornus (19-24), and Aquarius (24-31).

 

141P/Machholz
T = 2020-Dec-16  q = 0.81 au                                      Max El
Jupiter-family comet – 5.34-year period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S
2020-12-01  12.9   20 04  -10 01   0.841   0.901    52    Aql    27   10
2020-12-06  12.4   20 25  -09 48   0.822   0.847    52    Cap    28    8
2020-12-11  12.0   20 48  -09 35   0.811   0.792    52    Aqr    28    8
2020-12-16  11.6   21 12  -09 21   0.808   0.738    53    Aqr    29    8
2020-12-21  11.4   21 39  -09 08   0.813   0.686    54    Cap    30    8
2020-12-26  11.2   22 09  -08 53   0.826   0.638    56    Aqr    31    9
2020-12-31  11.1   22 41  -08 35   0.847   0.596    58    Aqr    32   12
2021-01-05  11.1   23 16  -08 12   0.875   0.562    62    Aqr    34   15
Comet Magnitude Parameters --- H = 14.0, 2.5n = 20.0, Offset = 10 days
                                                       [ref. S. Yoshida]

 

398P/Boattini - Comet Boattini was discovered on 2009 August 26 as a 18-19th magnitude object by Andrea Boattini with the 0.7-m Catalina Schmidt. During its 2009 return, the comet was a reasonably bright object reaching 12-13th magnitude. It was missed at its next return in 2015 but was recently recovered on 2020 August 11 at 19th magnitude by the ATLAS survey.  Observing circumstances are near optimal for its current orbit with perihelion occurring on 2020 December 17 at 1.31 au and closest approach to Earth a few days later on December 22 at 0.38 au. Chris Wyatt and J. J. Gonzalez both observed the comet in November to be at magnitude 13.2 to 13.9. 398P should brighten further to 12th magnitude this month as it moves through Eridanus (Dec 1-31) in the evening sky.

 

398P/Boattini
T = 2020-Dec-26  q = 1.31 au                                      Max El
Jupiter-family comet – 5.53-year period                            (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S
2020-12-01  12.9   04 24  -12 30   1.339   0.403   145    Eri    38   62 
2020-12-06  12.7   04 26  -11 32   1.327   0.392   145    Eri    39   61
2020-12-11  12.6   04 29  -10 08   1.318   0.384   145    Eri    40   60
2020-12-16  12.5   04 31  -08 19   1.311   0.378   144    Eri    42   58
2020-12-21  12.5   04 35  -06 07   1.307   0.376   144    Eri    44   56
2020-12-26  12.5   04 39  -03 34   1.306   0.376   143    Eri    47   53
2020-12-31  12.5   04 45  -00 45   1.307   0.380   142    Eri    49   51
2021-01-05  12.6   04 51  +02 15   1.310   0.387   141    Eri    52   48
            Comet Magnitude Parameters --- H = 12.3, 2.5n = 20.0

 

C/2020 P1 (NEOWISE) – Not to be confused with this summer’s bright C/2020 F3 (NEOWISE), C/2020 P1 is an intrinsically faint, dynamically new long-period comet first seen by the NEOWISE spacecraft on August 2. Though a faint 19th magnitude at discovery, it brightened to around magnitude 10 before being lost in the Sun’s glare. Last month we speculated that P1 had started to disintegrate which is not uncommon for intrinsically faint, dynamically new comets. Recent imaging confirms that C/2020 P1 has disintegrated and show a remnant dust trail. Still the comet is visually visible to large aperture observers with estimates placing it between 11th and 13th magnitude. The comet is slowly climbing higher in the eastern sky at dawn as it moves through Boötes (Dec 1), Virgo (1-11), and Serpens (11-31).

 

C/2020 P1 (NEOWISE)

T = 2020-Oct-20  q = 0.34 au                                      Max El
Long-Period comet – dynamically new                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020 12 01   ???   14 54  +07 30   1.085   1.689    37    Boo    19    0
2020 12 06   ???   15 03  +07 01   1.181   1.759    39    Vir    21    0
2020 12 11   ???   15 11  +06 37   1.274   1.822    42    Vir    24    0
2020 12 16   ???   15 18  +06 18   1.365   1.877    44    Ser    27    0
2020 12 21   ???   15 24  +06 03   1.454   1.925    47    Ser    30    0
2020 12 26   ???   15 30  +05 53   1.542   1.966    50    Ser    33    0
2020 12 31   ???   15 35  +05 47   1.627   2.001    53    Ser    35    0
2021 01 05   ???   15 40  +05 47   1.711   2.029    57    Ser    38    0

 

New Discoveries, Recoveries and Other Comets in the News

P/2020 V4 (Rankin) – David Rankin discovered P/2020 V4 with the Mount Lemmon 1.5-m on November 15 at 19th magnitude. This is the 6th comet named after David, all of which were found this year. P/2020 V4 is a borderline Centaur object with a perihelion of 5.15 au and orbital period of 28.5 years. Perihelion occurs next year on July 18, but the comet will be at its brightest around opposition this month and in early 2022. Even then it will only be a 19th magnitude object.

 

P/2020 V3 (PANSTARRS) – While P/2020 V4 is a borderline Centaur, P/2020 V3 (PANSTARRS) is a bona fide Centaur with a perihelion at 6.23 au and orbital period of 24.2 years. The object was discovered with the Pan-STARRS1 telescope on November 10 at 20th magnitude. Perihelion occurs on 2021 January 20 when the comet will be at its brightest at 19th magnitude.

 

C/2020 V2 (ZTF) – The Zwicky Transient Facility (ZTF) uses the 1.2-m Schmidt on Mount Palomar to search for all sorts of transient astronomical phenomenon including comets and asteroids. C/2020 V2 was found on November 2 at 19th magnitude and is a long-period comet with a 2.23 au perihelion on 2023 May 8. At discovery the comet was over 8 au from the Sun. The comet could brighten to 11th magnitude at that time, so this is one to watch in case it brightens more rapidly and becomes a visual object. This appears to be the first ZTF discovery to be named ‘ZTF’. Past ZTF finds were named “Palomar’ or after the individual observer.

 

P/2020 V1 = P/2005 XA54 (LONEOS-Hill) – In addition to discovering two comets last month, David Rankin also used the Mount Lemmon 1.5-m to recover P2005 XA54 (LONEOS-Hill) on November 16 at 18th magnitude. The ZTF survey also imaged the comet on November 3 and 5. P/2005 XA54 was discovered on 2005 December 4 by the LONEOS (Lowell Observatory Near Earth Object Search) 0.6-m Schmidt as an asteroidal object and on 2006 January 6 by ALPO Solar Section Coordinator Rik Hill with the 0.7-m Catalina Schmidt as a comet. During its 2006 return, the comet was observed to peak at 13th magnitude. This time the comet will come to perihelion on 2021 January 28 at 1.75 au when it should peak at 16th magnitude or brighter.

 

P/2020 W1 (Rankin) – The 5th comet to bear David Rankin’s name was actually found a day after P/2020 V4. It was 20th magnitude when spotted with the Mount Lemmon 1.5-m. Like P/2020 V4, P/2020 W1 is a borderline Centaur with a perihelion at 5.29 au back on 2020 April 3 and an orbital period of 19.3 years. The comet has likely already peaked in brightness.

 

As always, the Comet Section is happy to receive all comet observations, whether textual descriptions, images, drawings, magnitude estimates, or spectra. Please send your observations via email to < carl.hergenrother @ alpo-astronomy.org >.

 

Thank you to everyone who contributed to the ALPO Comets Section!

 

Stay safe and enjoy the sky!

- Carl Hergenrother (ALPO Comets Section Coordinator)

 

 

 

 

 

 

 

 

 

 

 

 

 


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#2 Carl H.

Carl H.

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Posted 04 December 2020 - 01:38 PM

Some quick updates on Erasmus and few fainter comets...

 

C/2020 S3 (Erasmus) still visible from the ground

 

Willian Souza has been able to visually observe C/2020 S3 the past two mornings. He estimated a brightness of 6.4 on Nov. 3.30 UT and 6.1 on Nov. 4.30 UT. The comet was small (2-3') and condensed (DC = 7). Willian's magnitude estimates show the comet to still be following the brightness prediction published above in the original post.

 

141P/Machholz is still there but faint

 

In the write-up in the original post, I mentioned that returning comet 141P/Machholz must be fainter than expected since no one had seen it since since August when it was 21st magnitude. Alan Hale and Richard Miles posted on comets-ml that they have recently been able to image 141P. The comet is still faint with Alan suggesting a brightness of 16-17th magnitude though a hint of a larger diffuse coma could mean it is brighter. This comet does brighten rapidly as it approaches perihelion so it may quickly come within range of large aperture visual observers.

 

P/2013 TL117 (Lemmon) has split

 

If you downloaded the PDF version of the this month's Comet News and looked closely at Denis Bucyznski's image of C/2013 TL117 (Lemmon), you would see that the comet has split with two components. I have received two more images, from Nick Haigh and Mike Olason, that confirm the dual nature of this comet. P/2013 TL117 is faint (17th magnitude or fainter) so this is only an imaging target.


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#3 Carl H.

Carl H.

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Posted 08 December 2020 - 12:34 PM

141P is in three pieces!

 

Michael Jager just posted an image of 141P/Machholz taken on December 7 to comets-ml. The image shows the primary at magnitude 13.5 and two fainter components, tentatively designated 141PA and141PB, at magnitude 17.5. 141PA and 141PB are ~9' and ~28' from the primary, respectively. 

 

Whether these "new" components are really new or have been seen at previous apparitions is TBD.

 

Ephemerides for the new components can be found on the MPC's PCCP page.



#4 Carl H.

Carl H.

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Posted 18 December 2020 - 04:33 PM

C/2020 S3 (Erasmus) is visible in SOHO LASCO C3 images

 

Comet Erasmus is no longer visible from the ground. Well, that's true as long as you weren't in the path of totality of a solar eclipse. During Monday's eclipse, Erasmus and C/2020 X3 (SOHO), a short-lived small Sungrazing comet, were both observed during totality. See: http://nickdjames.co...14_1609_ndj.jpg

 

C/2020 X3 failed to survive its close brush with the Sun, but Erasmus is still going strong at around 5th magnitude and visible in images taken with the SOHO LASCO C3 coronagraph camera. 

 

Go here for the latest SOHO LASCO L3 image: https://soho.nascom....024/latest.html

 

The comet can be seen with a nice tail near the right edge of the image just above center.


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