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ALPO Comet News for August 2021

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#1 Carl H.

Carl H.

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Posted 05 August 2021 - 05:39 PM

ALPO COMET NEWS FOR AUGUST 2021
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. We can also be reached at < comets @ alpo-astronomy.org >.

 

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.

 

Comets Calendar for August 2021

 

Aug 01 – 7P/Pons-Winnecke (Mag 10) and 19P/Borrelly (Mag 16) within 1.5 deg of each other
Aug 01 – 15P/Finlay within 0.25 deg of open cluster NGC 1746
Aug 02 – 67P/Churyumov-Gerasimenko within 0.15 deg of 13th mag galaxy NGC 645
Aug 05-06 – 67P/Churyumov-Gerasimenko within 0.5 deg of 12th mag galaxies NGC 676, 693, & 706
Aug 08 – New Moon
Aug 08 – 67P/Churyumov-Gerasimenko within 0.15 deg of 13th mag galaxy NGC 645
Aug 09-10 – 67P/Churyumov-Gerasimenko within 0.1 deg of 14th mag galaxy IC 182
Aug 11 – 15P/Finlay within 0.75 deg of southern edge of supernova remnant Simeis 147
Aug 15 – First Quarter Moon
Aug 18 – 332P/Ikeya-Murakami at perihelion (q = 1.58 au, 5.4-year orbit, V~20, poor apparition, comet currently unobservable due to proximity to Sun)
Aug 18 – 106P/Schuster at perihelion (q = 1.53 au, 7.3-year orbit, V~15)
Aug 19 – C/2020 M5 (ATLAS) at perihelion (q = 3.00 au, V~15)
Aug 21 – 4P/Faye within ~0.5 deg of NGC 1555 (Hind’s Variable Nebula)
Aug 22 – Full Moon
Aug 24 – 67P/Churyumov-Gerasimenko within 0.25 deg of 13th mag galaxies NGC 1024, 1028 & 1029
Aug 25 – 193P/LINEAR-NEAT at perihelion (q = 2.17 au, 6.8-year orbit, V~16)
Aug 26 – P/2008 WZ96 (LINEAR) at perihelion (q = 1.85 au, 6.2-year orbit, V~20, not yet recovered)
Aug 27 – 8P/Tuttle at perihelion (q = 1.03 au, 13.6-year orbit, V~8)
Aug 28 – C/2021 K2 (MASTER) at perihelion (q = 5.47 au, V~18)
Aug 28 – C/2020 O2 (Amaral) at perihelion (q = 4.86 au, V~15)
Aug 28 – 15P/Finlay within 0.1 deg of open cluster NGC 2266
Aug 28 – C/2020 T2 (PANSTARRS) within 0.4 deg of 12th mag galaxy NGC 5878
Aug 30 – Last Quarter Moon
Aug 30 – 4P/Faye within 0.25 deg of open cluster NGC 1647
Aug 31 – C/2019 L3 (ATLAS) within 0.05 deg of 13th mag galaxy NGC 2303

 

Comets Brighter Than Magnitude 10

 

C/2021 O1 (Nishimura)

 

Discovered 2021 July 21 at 9-10th magnitude by amateur Hideo Nishimura with a DLSR + 200mm lens

Discovery Telescope: 1.2-m Samuel Oschin Schmidt on Mount Palomar
Perihelion on 2021 August 13 at 0.79 au, inclination = 27.6 deg, eccentricity = 1.0

 

C/2021 O1 (Nishimura)                                             Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  07 37  +31 29   0.829   1.705    20M   Gem   9.5     2    0
2021-Aug-06  08 11  +31 02   0.808   1.702    18M   Cnc   9.4     0    0
2021-Aug-11  08 44  +30 00   0.797   1.709    17M   Cnc   9.4     0    0
2021-Aug-16  09 16  +28 25   0.799   1.725    15M   Cnc   9.4     0    0
2021-Aug-21  09 47  +26 22   0.812   1.750    14M   Leo   9.5     0    0
2021-Aug-26  10 15  +23 58   0.835   1.784    13M   Leo   9.7     0    0
2021-Aug-31  10 41  +21 20   0.868   1.825    12E   Leo   9.9     0    0
2021-Sep-05  11 05  +18 34   0.910   1.872    11E   Leo  10.1     0    0
Comet Magnitude Parameters --- H = 9.2, 2.5n = 10.0

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
   2021O1  2021 07 26.47  C  9.2 GG 27.9T 6A270   1.3               ICQ xx OLAxx Mike Olason

 

Amateur astronomer Hideo Nishimura of Gansho-ji, Kakegawa, Japan, discovered a 9-10th magnitude comet at an amazingly small solar elongation of 23 degrees. Nishimura found the comet on July 21 with a Canon EOS 6D digital camera and 200-mm f/3.2 lens. At discovery, the new comet was located ~2 degrees from 8P/Tuttle. This is Nishimura's 2nd discovery, his first was the visual discovery C/1994 N1 (Nakamura-Nishimura-Machholz). [Ref: MPEC 2021-O47, CBET 5004, 5008]

 

C/2021 O1 (Nishimura) is a long-period comet with perihelion on August 13 at 0.79 au. The comet is unfortunately poorly placed on the other side of the Sun for the perihelic part of its apparition.

 

It might have been observable from the southern hemisphere in June but was at a low elevation of ~7 deg at the start of astronomical twilight and around 12th magnitude. Nishimura discovered the comet in the morning during a short window of opportunity for northern observers when it was visible at only a degree or three above the horizon before the start of astronomical twilight.

 

The comet will be even more difficult to observe in August. Perhaps observers with a flat eastern horizon will be able to observe the comet at the start of the month deep in nautical twilight. But after a few days to a week, the comet should be too close to the Sun for most, if not all, observers. Solar elongation is slowly shrinking to a minimum of 6 degrees in mid-October. It will once again become visible to northern observers in December though the comet will likely be very faint by then. Southern observers will have to wait till January 2022.

 

Comets Between Magnitude 10 and 13

 

C/2020 T2 (Palomar)

 

Discovered 2020 October 7 at 19th magnitude by the Zwicky Transient Facility (ZTF)
Discovery Telescope: 1.2-m Samuel Oschin Schmidt on Mount Palomar
Perihelion on 2021 July 11 at 2.05 au, inclination = 27.9 deg, eccentricity = 0.9935
Dynamically old long-period comet with orbital period of ~5600 years

 

C/2020 T2 (Palomar)                                               Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  14 26  -03 47   2.070   1.858    87E   Vir  10.1    28   52
2021-Aug-06  14 34  -05 51   2.078   1.910    84E   Vir  10.2    26   53
2021-Aug-11  14 41  -07 52   2.088   1.965    82E   Vir  10.3    24   53
2021-Aug-16  14 50  -09 48   2.099   2.022    80E   Lib  10.3    22   53
2021-Aug-21  14 58  -11 40   2.112   2.081    77E   Lib  10.4    20   53
2021-Aug-26  15 07  -13 27   2.126   2.142    75E   Lib  10.5    18   52
2021-Aug-31  15 16  -15 10   2.142   2.204    73E   Lib  10.6    17   50
2021-Sep-05  15 25  -16 48   2.160   2.269    70E   Lib  10.7    15   49
Comet Magnitude Parameters --- H = 5.6, 2.5n = 10.0

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
   2020T2  2021 07 31.48 xM 10.4 AQ 40.0L 4  59   4.0  6            ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 30.44 xM 10.6 AQ 40.0L 4  59   4.0  6            ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 29.39 xM 10.4 AQ 40.0L 4  59   6.0  5            ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 27.91  S  9.9 TK 20.3T10  77   6    3/           ICQ XX GON05 J J Gonzalez Suarez
   2020T2  2021 07 27.40 xM 10.4 TK 25.0L 5  40   5.0  5            ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 13.94  S  9.8 TK 20.3T10  77   6    3/           ICQ XX GON05 J J Gonzalez Suarez
   2020T2  2021 07 12.40 xM 10.5 AQ 40.0L 4  59   4.5  6            ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 08.94  S  9.7 TK 20.3T10  77   7    3/           ICQ XX GON05 J J Gonzalez Suarez
   2020T2  2021 07 05.91  E 10.5 TK 25.0C10  62   5    3            ICQ XX DECaa Michel Deconinck
   2020T2  2021 07 05.43 xM 10.5 AQ 40.0L 4  59   4.2  5/           ICQ XX WYA   Christopher Wyatt
   2020T2  2021 07 04.96  S  9.8 TK 20.3T10  77   6    3/           ICQ XX GON05 J J Gonzalez Suarez
   2020T2  2021 07 04.36 xM 10.4 AQ 25.0L 5  40   3.8  5            ICQ XX WYA   Christopher Wyatt

 

C/2020 T2 (PANSTARRS) has spent the past 2 months around magnitude 10. Now post its July 11 perihelion and moving away from the Earth, the comet should begin to slowly fade this month. Michel Deconinck, J. J. Gonzalez and Chris Wyatt made a dozen magnitude measurements in July and found the comet to be between magnitude 9.7 and 10.6. There does seem to be an aperture effect at work as the fainter visual measurements correspond to larger apertures. Michel, J. J., and Chris reported the comet to be tailless with a coma diameter between 3.8 and 7’ and a degree of condensation between 3.5 and 6.

 

August should see the comet fade from around magnitude 10.1 to 10.6 as it moves through the evening constellations of Virgo (Aug 1-12) and Libra (12-31). Towards the end of the month on August 28, there may be a photo op with C/2020 T2 passing within 0.4 deg of 12th mag galaxy NGC 5878.

 

4P/Faye

 

Discovered on 1843 November 23 by the Herve Faye
Perihelion on 2021 September 9 at 1.62 au, inclination = 8.0 deg, eccentricity = 0.58
Short-period comet with orbital period of ~7.48 years

 

4P/Faye                                                           Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  03 22  +17 57   1.668   1.595    75M   Ari  11.3    39   30
2021-Aug-06  03 36  +18 20   1.657   1.552    77M   Tau  11.1    42   29
2021-Aug-11  03 50  +18 38   1.647   1.510    78M   Tau  11.0    44   29
2021-Aug-16  04 04  +18 50   1.638   1.470    80M   Tau  10.9    47   29
2021-Aug-21  04 18  +18 56   1.631   1.432    81M   Tau  10.7    49   29
2021-Aug-26  04 32  +18 56   1.626   1.395    83M   Tau  10.6    52   29
2021-Aug-31  04 45  +18 51   1.622   1.359    85M   Tau  10.6    54   29
2021-Sep-05  04 59  +18 39   1.620   1.325    86M   Tau  10.5    56   29
Comet Magnitude Parameters --- H =  3.7, 2.5n =  29.5

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
  4        2021 07 26.38  C 12.3 GG 27.9T 6A540   1.3       8  m256 ICQ xx OLAxx Mike Olason
  4        2021 07 22.08  I 11.0:TK 12.6B 5  62 & 1    6            ICQ XX DECaa Michel Deconinck
  4        2021 07 14.09  S 10.8 TK 20.3T10  77   4    2/           ICQ XX GON05 J J Gonzalez Suarez
  4        2021 07 09.08  S 11.1 TK 20.3T10 100   4    2/           ICQ XX GON05 J J Gonzalez Suarez

 

Comet 4P/Faye was discovered visually by Herve Faye on 1843 November 23 at 5th-6th magnitude. This year’s apparition is its 22nd observed return. At its best returns in 1991 and 2006, Faye reached 9th magnitude. 2021 is a moderately good but not great return and should see Faye reach magnitude 10.3 at the end of September.

 

Three visual observations from Michel Deconinck and J. J. Gonzalez found Faye between 10.8 and 11.1 with a coma ranging from 1’ to 4’. A CCD measurement by Mike Olason came in a little fainter at magnitude 12.3 with a 1.3’ coma. The image showed the development of a long dust tail and a hint of asymmetry in the coma.

Perihelion occurs on September 8 at 1.62 au followed by a minimum distance to Earth a few months later on December 5 at 0.94 au. Faye is currently a morning object observable from both hemispheres and should brighten from around magnitude 12.4 to 11.2 as its moves through Aries (Aug 1) and Taurus (2-30).

 

6P/d’Arrest

 

Discovered on 1851 June 28 by the Heinrich Ludwig d'Arrest
Perihelion on 2021 September 17 at 1.35 au, inclination = 19.5 deg, eccentricity = 0.61
Short-period comet with orbital period of ~6.54 years

 

6P/d'Arrest                                                       Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  16 17  +02 43   1.461   0.746   111E   Ser   14.4   48   47 
2021-Aug-06  16 22  +00 08   1.441   0.747   108E   Oph   14.0   45   50
2021-Aug-11  16 29  -02 32   1.423   0.749   106E   Oph   13.7   43   53
2021-Aug-16  16 36  -05 16   1.406   0.753   104E   Oph   13.3   40   55
2021-Aug-21  16 45  -08 03   1.392   0.759   102E   Oph   13.0   37   58
2021-Aug-26  16 55  -10 49   1.380   0.766   101E   Oph   12.6   34   61
2021-Aug-31  17 07  -13 33   1.370   0.776    99E   Oph   12.3   32   63
2021-Sep-05  17 20  -16 12   1.363   0.788    97E   Oph   12.0   30   65
Comet Magnitude Parameters --- H =  3.5, 2.5n =  45.0, offset = +60 days

 

Heinrich Louis d’Arrest discovered 6P visually in June 1851 though we now know that it had been previously observed by another astronomer, Phillipe la Hire, in 1678. Long-time comet watchers may remember this comet’s excellent apparition in 1976 when it passed 0.15 au from Earth and reached 5th magnitude. d’Arrest’s perihelion distance is larger now at 1.35 au so such close approaches are not currently possible. This year closest approach to Earth will be on August 2 at 0.75 au and perihelion on September 17 at 1.35 au.

 

No visual observations of d’Arrest have been submitted to the ALPO or COBS yet for the current apparition. Several CCD observations have been submitted to the COBS site. In July, most observers reported d’Arrest at ~17th magnitude with a small sub-arc minute coma. Michael Lehmann observed the comet on the 28th and 29th and found it to be much brighter (12.7-13.4) and larger (5.6-7.1’). His measurements are brighter than the prediction above which is based on photometric parameters by Seiichi Yoshida (http://www.aerith.ne...0006P/2021.html). According to the prediction, d’Arrest should rapidly brighten in August from around magnitude 14.4 to 12.3 as it moves through the evening constellations of Serpens (Aug 1-5), Ophiuchus (5-30).

 

Most comets fade as they move away from the Sun and Earth, but d’Arrest experiences a seasonal effect resulting in a peak brightness up to 60 days after perihelion. As a result, a maximum brightness around magnitude 9.8 should occur in the late October / early November time frame.

 

7P/Pons-Winnecke

 

Discovered on 1819 June 12 by the Jean-Luis Pons
Rediscovered on 1858 March 9 by Friedrich August Theodor Winnecke
Perihelion on 2021 May 27 at 1.23 au, inclination = 22.4 deg, eccentricity = 0.64
Short-period comet with orbital period of ~6.31 years

 

7P/Pons-Winnecke                                                  Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  00 06  -46 59   1.468   0.595   129M   Phe  11.2     3   83
2021-Aug-06  00 07  -48 33   1.500   0.623   131M   Phe  11.4     1   81
2021-Aug-11  00 05  -49 50   1.533   0.654   132M   Phe  11.7     0   80
2021-Aug-16  00 02  -50 49   1.567   0.688   133M   Phe  11.9     0   79
2021-Aug-21  23 58  -51 31   1.601   0.724   134M   Phe  12.2     0   79
2021-Aug-26  23 52  -51 54   1.637   0.762   134M   Phe  12.5     0   78
2021-Aug-31  23 46  -52 01   1.673   0.803   134M   Phe  12.8     0   78
2021-Sep-05  23 40  -51 51   1.710   0.847   134M   Phe  13.1     0   78
Comet Magnitude Parameters --- H =  10.1, 2.5n = 19.7, offset = +34 days

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
  7        2021 07 31.51 xM 11.8 AQ 40.0L 4  59   6.0  3/           ICQ XX WYA   Christopher Wyatt
  7        2021 07 30.50 xM 13.0 AQ 40.0L 4 108   1.9  6            ICQ XX WYA   Christopher Wyatt
  7        2021 07 29.47 xM 12.4 AQ 40.0L 4 108   1.8  5/           ICQ XX WYA   Christopher Wyatt
  7        2021 07 26.43  C 12.2 GG 27.9T 6A300   1.3           288 ICQ xx OLAxx Mike Olason
  7        2021 07 12.74 xM 11.2 AQ 40.0L 4  59   3.1  5            ICQ XX WYA   Christopher Wyatt
  7        2021 07 09.11  S 10.5 TK 20.3T10 100   5    2/           ICQ XX GON05 J J Gonzalez Suarez
  7        2021 07 06.71 xM 11.8 AQ 40.0L 4  59   4.8  6            ICQ XX WYA   Christopher Wyatt

 

Comet 7P/Pons-Winnecke was an 8th magnitude object when visually discovered by Jean-Luis Pons on 1819 June 12. It was re-discovered thirty-nine years later on 1858 March 9 by Friedrich August Theodor Winnecke. Throughout the 19th and early 20th century, Pons-Winnecke was routinely a bright object and often reached 6th magnitude during its better placed apparitions. Its best apparition occurred in 1927 when it reached 3rd magnitude during an especially close approach to Earth (0.04 au).

 

Gravitational perturbations have increased its perihelion distance from a 0.76 au in 1841 to a maximum of 1.26 au in 1989. As a result, it hasn’t had a bright return since 1939 (6th magnitude) and nowadays usually gets no brighter than ~10-11th magnitude. Over the coming decades, Pons-Winnecke’s perihelion distance will decrease from this year’s 1.23 au to 1.13 au in 2027, 0.98 au in 2039, 0.87 au in 2051, and a minimum near 0.84 au for perihelia between 2062 through the end of the 21st century. The smaller distances will result in close approaches to Earth in 2045 (0.21 au), 2062 (0.17 au), 2073 (0.19 au), and 2084 (0.31 au). Check out Kazuo Kinoshita’s Comet Orbit Page entry for 7P for more details on 7P’s past and future orbital evolution at http://jcometobs.web...pcmtn/0007p.htm.

 

Six visual and a CCD magnitude estimate were submitted to the Comets Section by J. J. Gonzalez, Mike Olason, and Chris Wyatt. The observations found a large range of coma diameters (1.3’ to 6’), DC values (2.5 to 6), and magnitudes (10.5 to 13.0). The scatter in coma parameters and brightness suggests a low surface brightness coma sensitive to telescope aperture and observing technique. Confirming this point, CCD measurements submitted by Michel Lehmann (ICQ code LEHaa) to the COBS site, found a larger coma in July (between 15’ and 20’) resulting in brighter object (between 10.0 and 10.5).

 

In the past, Pons-Winnecke has reached peak brightness in the weeks after perihelion. This year was no different. Perihelion was back on May 27, but the comet appeared at its brightest roughly a month later in late June/early July. Observations at the end of July show the beginning of a fading trend which should continue as the comet moves away from both the Sun and Earth. August should see the comet fade from around magnitude 11 to 13 as it moves through the southern constellation of Phoenix (14-31). Its location at southern declinations of -47 to -52 makes it an invisible object from northern mid-latitudes but well placed for southern hemisphere observers.

 

Photo Ops: At the beginning of August, 7P/Pons-Winnecke and 16th magnitude 19P/Borrelly will be located within a few degrees of each other. While Pons-Winnecke is fading, Borrelly is brightening and should peak around 9th magnitude in January/February 2022.

 

8P/Tuttle

 

Discovered on 1790 January 9 by Pierre F. A. Mechain
Rediscovered on 1858 January 5 by Horace Tuttle
Perihelion on 2021 August 27 at 1.03 au, inclination = 54.9 deg, eccentricity = 0.82
Short-period comet with orbital period of ~13.6 years

 

8P/Tuttle                                                         Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  07 15  +24 38   1.104   1.982    21M   Gem  10.7     0    0
2021-Aug-06  07 31  +21 29   1.079   1.948    22M   Gem  10.3     0    0
2021-Aug-11  07 48  +18 08   1.058   1.917    22M   Gem  10.0     0    0
2021-Aug-16  08 04  +14 35   1.042   1.888    23M   Cnc   9.7     0    0
2021-Aug-21  08 20  +10 52   1.031   1.863    24M   Cnc   9.4     0    2
2021-Aug-26  08 36  +07 00   1.026   1.842    25M   Cnc   9.2     0    4
2021-Aug-31  08 52  +03 01   1.027   1.825    26M   Hya   9.0     0    6
2021-Sep-05  09 08  -01 01   1.034   1.814    27M   Hya   8.8     0    8
Comet Magnitude Parameters --- H = 7.0, 2.5n =  20.0, offset = +25 days [Ref: Seiichi Yoshida]

 

Similar to the discovery story of Pons-Winnecke, 8P/Tuttle was discovered during two widely separated apparitions. Pierre François André Méchain made the first discovery in January 1790. Sixty-eight years later, 8P was re-discovered by Horace Parnell Tuttle in January 1858. With a 13.6-year period, 8P/Tuttle is making its 13th observed return. Tuttle’s relatively large semi-major axis of 5.7 au and inclination of 54.9° makes it a Halley-type rather than a Jupiter-family comet.

 

The current return is poor with Tuttle arriving at perihelion nearly on the opposite side of the Sun from Earth. Even with such poor placement and a minimum distance to Earth on September 12 of 1.81 au, Tuttle is expected to brighten to magnitude 8.5 in September.

 

For yet another month, Tuttle is located at a very low solar elongation (21-26 deg) and will be difficult to observe. This should improve by the end of the month as the comet will start to move out of the glow of the dawn as a 9th magnitude object for southern observers. Tuttle’s large inclination results in it spending most of its time post-perihelion far south of the ecliptic, as a result the comet won’t be visible to northern observers until it has faded beyond the reach of visual observers.

 

15P/Finlay

 

Discovered 1886 September 26 by the William Henry Finlay
Perihelion on 2021 July 13 at 0.99 au, inclination = 6.8 deg, eccentricity = 0.72
Short-period comet with orbital period of ~6.56 years

 

15P/Finlay                                                        Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  05 00  +23 49   1.028   1.262    52M   Tau  11.1    24   15
2021-Aug-06  05 20  +24 46   1.049   1.291    52M   Tau  11.3    26   13
2021-Aug-11  05 39  +25 31   1.074   1.320    52M   Tau  11.5    28   12
2021-Aug-16  05 58  +26 05   1.103   1.347    53M   Tau  11.7    29   11
2021-Aug-21  06 16  +26 29   1.135   1.374    54M   Gem  12.0    31   10
2021-Aug-26  06 33  +26 45   1.171   1.398    55M   Gem  12.2    33    9
2021-Aug-31  06 49  +26 54   1.208   1.420    56M   Gem  12.5    35    9
2021-Sep-05  07 04  +26 58   1.248   1.439    58M   Gem  12.7    37    8
Comet Magnitude Parameters --- H = 10.4, 2.5n =  16.0

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
15        2021 07 26.48  C 12.8 GG 27.9T 6A300   1.3               ICQ xx OLAxx Mike Olason
15        2021 07 14.11  S 10.2 TK 20.3T10 100   5    3            ICQ XX GON05 J J Gonzalez Suarez
15        2021 07 12.77 xM 11.3 AQ 40.0L 4  59   2.6  4            ICQ XX WYA   Christopher Wyatt
15        2021 07 06.76 xM 11.1 AQ 40.0L 4  59   2.9  4            ICQ XX WYA   Christopher Wyatt

 

15P/Finlay was discovered in 1886 by William Henry Finlay at the Royal Observatory at Cape of Good Hope in South Africa. This apparition marks the 16th observed return of 15P. Its best return was in 1906 when it passed 0.27 au from Earth and reached 6th magnitude. During its previous return in 2014/2015, 15P experienced two outbursts of 2-3 mag outburst with the brightest reaching 7th magnitude.

 

Chris Wyatt visually observed 15P at magnitude 11.1 and 11.3 on July 6 and 12 with his 0.40-m f/4 reflector. J. J. Gonzalez found the comet to be brighter (10.2) and larger (~5’ vs Chris’ 2.6-2.9’). Aperture correcting Chris’s measurements do make them 0.9 magnitudes brighter and more in line with J. J.’s observations.

 

Perihelion was last month on July 13th at 0.99 au, Finlay should now be fading from ~11th to 12th magnitude as it moves away from the Earth and Sun. The comet is a morning object in Taurus (Aug 1-16) and Gemini (16-30).

 

67P/Churyumov-Gerasimenko

 

Discovered 1969 September 11 by the Klim Ivanovic Churyumov and Svetlana Ivanovna Gerasimenko
Perihelion on 2021 November 2 at 1.21 au, inclination = 3.9 deg, eccentricity = 0.65
Short-period comet with orbital period of ~6.43 years

 

67P/Churyumov-Gerasimenko                                         Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  01 36  +05 16   1.646   1.070   104M   Psc  13.7    48   45
2021-Aug-06  01 49  +06 27   1.609   1.004   105M   Psc  13.5    51   43
2021-Aug-11  02 02  +07 40   1.573   0.940   107M   Psc  13.2    53   42
2021-Aug-16  02 15  +08 55   1.537   0.880   108M   Cet  12.9    56   41
2021-Aug-21  02 29  +10 12   1.502   0.824   109M   Cet  12.7    58   40
2021-Aug-26  02 44  +11 32   1.469   0.770   110M   Ari  12.4    60   38
2021-Aug-31  03 00  +12 54   1.436   0.721   111M   Ari  12.1    62   37
2021-Sep-05  03 16  +14 18   1.405   0.675   111M   Ari  11.8    64   35
Comet Magnitude Parameters --- H = 9.5, 2.5n =  14.0, offset = +40 days [Ref: Seiichi Yoshida]

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
67        2021 07 12.76 xM 15.0 AQ 40.0L 4 182   0.4  5/           ICQ XX WYA   Chris Wyatt
67        2021 07 06.73 xM 15.1 AQ 40.0L 4 261   0.3  6            ICQ XX WYA   Chris Wyatt

 

67P was discovered on plates taken on 1969 September 11 by Kiev University Astronomical Observatory astronomers Klim Ivanovic Churyumov and Svetlana Ivanovna Gerasimenko working with a 50-cm Maksutov astrograph at the Alma-Ata Astrophysical Institute in current day Kazakhstan. This apparition is 67P’s 9th observed return with perihelion occurring on 2021 November 2 at 1.21 au. A close approach to Earth at 0.42 au on November 12 results in the comet’s best return since 1982 when it came marginally closer to Earth at 0.39 au. At that return, a peak brightness of 9th magnitude was reached. A similar brightness should occur this November and December when it will be a morning object visible from both hemispheres. Like 19P, 67P was also the target of a spacecraft mission. The ESA Rosetta and Philae crafts are the only spacecraft to have orbited and landed on a comet. This will be 67P’s first return since Rosetta ended its mission by soft landing onto the comet’s surface.

 

Chris Wyatt spied 67P twice in July and found the comet to be magnitude 15.0 and 15.1. Aperture correction suggests the comet is closer to 14.0 which is in line with the prediction for the comet to brighten from magnitude 13.7 to 12.1 this month as it moves through Pisces (Aug 1-12), Cetus (12-22) and Aries (22-30) in the morning sky.

 

C/2017 K2 (PANSTARRS)

 

Discovered 2017 May 21 by the Pan-STARRS survey with the Pan-STARRS1 1.8-m on Haleakala
Perihelion on 2022 December 19 at 1.80 au, inclination = 87.6 deg, eccentricity = 1.00008
Dynamically old long-period comet

 

C/2017 K2 (PANSTARRS)                                             Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  17 08  +38 35   5.724   5.391   104E   Her  13.0    84   11
2021-Aug-06  17 05  +37 43   5.682   5.383   102E   Her  13.0    81   12
2021-Aug-11  17 03  +36 48   5.639   5.378    99E   Her  13.0    78   13
2021-Aug-16  17 01  +35 51   5.597   5.376    97E   Her  12.9    76   14
2021-Aug-21  16 59  +34 52   5.555   5.377    94E   Her  12.9    73   15
2021-Aug-26  16 58  +33 51   5.512   5.379    92E   Her  12.9    70   16
2021-Aug-31  16 57  +32 50   5.470   5.384    89E   Her  12.9    68   17
2021-Sep-05  16 56  +31 48   5.427   5.390    86E   Her  12.8    65   17
Comet Magnitude Parameters --- H =  3.6, 2.5n =  7.6

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
   2017K2  2021 07 31.48 xM 13.2 AQ 40.0L 4 108   1.0  3/           ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 30.45 xM 13.3 AQ 40.0L 4 182   1.0  5/           ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 29.40 xM 13.2 AQ 40.0L 4 108   1.5  4            ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 27.92  S 12.2 AQ 20.3T10 133   1.0  4/           ICQ XX GON05 Juan Jose Gonzalez Suarez
   2017K2  2021 07 27.41 xM 13.5 AQ 25.0L 5 179   0.8  3            ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 13.96  S 12.1 AQ 20.3T10  77   1.5  4            ICQ XX GON05 Juan Jose Gonzalez Suarez
   2017K2  2021 07 12.42 xM 13.5 AQ 40.0L 4 108   1    5/           ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 08.96  S 12.2 AQ 20.3T10 100   1.5  4            ICQ XX GON05 Juan Jose Gonzalez Suarez
   2017K2  2021 07 05.88  I 13.0:TK 25.0C10 192        7            ICQ XX DECaa Michel Deconinck
   2017K2  2021 07 05.49 xM 13.5 AQ 40.0L 4 182   1    5/           ICQ XX WYA   Christopher Wyatt
   2017K2  2021 07 04.98  S 12.3 AQ 20.3T10 133   1.5  4            ICQ XX GON05 Juan Jose Gonzalez Suarez

 

C/2017 K2 (PANSTARRS) was discovered on 2017 May 21 by the Pan-STARRS1 1.8-m telescope at Haleakala on the Hawaiian island of Maui. At discovery the comet was around 21st magnitude and located at 16.1 au from the Sun. Pre-discovery observations were found back to May of 2013 when the comet was 23.7 au from the Sun. For comparison Uranus has a semi-major axis of 19.2 au.

 

C/2017 K2 (PANSTARRS) is still 16 months from a 2022 December 19 perihelion at 1.80 au when it should reach 7th magnitude (if its current 2.5n ~ 7.6 brightening trend continues). A large number of visual observations were made in July by Michel Deconinck, J. J. Gonzalez and Chris Wyatt. They found a small comet with a coma diameter between 0.8’ and 1.5’. Chris placed the comet between magnitude 13.2 and 13.5. Michel’s sole observation was a little brighter at 13.0 while J. J. was the brightest at magnitude 12.1 to 12.3.

 

C/2017 K2 remains a northern object in Hercules though still observable from the southern hemisphere as shown by Chris Wyatt’s observations from Australia. The comet will continue to slowly brighten throughout the remainder of 2021 and all of 2022.

 

C/2019 L3 (ATLAS)

 

Discovered 2017 May 21 by the Pan-STARRS survey with the Pan-STARRS1 1.8-m on Haleakala
Perihelion on 2022 January 9 at 3.55 au, inclination = 48.4 deg, eccentricity = 1.0016
Dynamically new long-period comet

 

C/2019 L3 (ATLAS)                                                 Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  06 09  +47 40   3.845   4.522    43M   Aur  11.5    25    0
2021-Aug-06  06 18  +47 21   3.828   4.467    45M   Aur  11.4    28    0
2021-Aug-11  06 26  +47 02   3.812   4.410    48M   Aur  11.4    30    0
2021-Aug-16  06 33  +46 41   3.796   4.350    51M   Aur  11.3    33    0
2021-Aug-21  06 41  +46 20   3.780   4.287    53M   Aur  11.3    36    0
2021-Aug-26  06 48  +45 58   3.765   4.222    56M   Aur  11.2    39    0
2021-Aug-31  06 55  +45 35   3.750   4.154    59M   Aur  11.2    42    0
2021-Sep-05  07 01  +45 12   3.736   4.084    63M   Aur  11.1    45    0
Comet Magnitude Parameters --- H = 3.5, 2.5n = 8.0

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
   2019L3  2021 07 14.12  S 11.2 TK 20.3T10 100   2.5  3/           ICQ XX GON05 Juan Jose Gonzalez Suarez
   2019L3  2021 07 09.09  S 11.4 TK 20.3T10 133   2.5  3/           ICQ XX GON05 Juan Jose Gonzalez Suarez

 

C/2019 L3 passed north of the Sun a few weeks ago and is now a morning object for northern hemisphere observers as it moves through Auriga.

J. J. Gonzalez made two observations of L3 in July finding the comet at magnitude 11.4 on the 9th and 11.2 on the 14th with a 2.5’ coma on both nights.

 

C/2019 L3 is still 5 months from a 2022 January 9 perihelion at 3.57 au. The large perihelion distance means C/2019 L3 should remain a visual object well into 2022 and possibly even 2023. If the comet brightens at a conservative 2.5n = 8 rate, it could reach magnitude 10.0 at the end of 2021 when it will be well placed in the opposition sky.

 

Fainter Comets of Interest (Fainter than 13.0)

 

C/2021 A1 (Leonard)

 

Discovered 2021 January 3 by Greg Leonard of the Catalina Sky Survey with the 1.5-m on Mount Lemmon
Perihelion on 2022 January 3 at 0.61 au, inclination = 132.7 deg, eccentricity = 1.00002
Dynamically old long-period comet

 

C/2021 A1 (Leonard)                                               Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  10 35  +46 07   2.698   3.449    36E   UMa  16.3    19    0
2021-Aug-06  10 38  +45 18   2.632   3.402    34E   UMa  16.2    17    0
2021-Aug-11  10 40  +44 31   2.566   3.350    33E   UMa  16.0    15    0
2021-Aug-16  10 43  +43 44   2.500   3.291    32E   UMa  15.9    14    0
2021-Aug-21  10 46  +42 59   2.433   3.226    32E   UMa  15.8    12    0
2021-Aug-26  10 50  +42 16   2.365   3.154    32E   UMa  15.6    11    0
2021-Aug-31  10 53  +41 33   2.297   3.076    33E   UMa  15.5     9    0
2021-Sep-05  10 57  +40 52   2.228   2.992    33M   UMa  15.3     8    0 
Comet Magnitude Parameters --- H = 10.3, 2.5n = 7.6

 

Recent Magnitude Measurements in ICQ format:
Comet Des  YYYY MM DD.DD     Mag SC APER FL POW    COMA     TAIL        ICQ CODE Observer Name
                (UT)                    T         Dia  DC  LENG  PA
   2021A1  2021 07 05.23  V 17.3 U4 61.0Y 7A200   0.5       0.6m 85 ICQ xx HER02 Carl Hergenrother

 

C/2021 A1 (Leonard) was found on 2021 January 3 by Greg Leonard with the Mount Lemmon 1.5-m reflector. At discovery, it was around 19th magnitude and located 5.1 au from the Sun.

 

C/2021 A1 has the potential to become a nice object at the end of the year due to a relatively small perihelion of 0.62 au on 2022 January 3, a close approach to within 0.233 au from Earth on December 12, and a phase angle that reaches a maximum of 160 degrees at the time of close approach which may result in a few magnitudes of enhanced brightness due to forward scattering of light by cometary dust. Working against are a small solar elongation at the time of maximum brightness (a minimum elongation of 15 deg) and the comet’s slow rate of brightening.

 

I was able to observe the comet with one of the iTelescopes.net 0.6-m telescopes at magnitude 17.3 on July 5. Only one a single observation has been submitted to COBS since then (Michael Lehmann found Leonard at magnitude 16.2 on July 30). The new data confirms that Leonard is still brightening at a rate of 2.5n ~ 7.6 which would result in a peak brightness around magnitude 6.3. Even with 2-3 magnitudes of dust forward scattering enhancement, Leonard may be a very difficult object to observe when at its best.

 

C/Leonard is an evening object near 15-16th magnitude located in Ursa Major. The comet is far enough north of the Sun that it will be observed through its upcoming solar conjunction in early September though it will be a very low object in August and September (and below the horizon for southern hemisphere observers). Imagers and large aperture visual observers are strongly encouraged to monitor C/2021 A1 over the coming months.

 

C/2021 O3 (PANSTARRS)

 

Discovered 2021 July 26 by Pan-STARRS with the 1.8-m Pan-STARRS1 1.8-m on Haleakala
Perihelion on 2022 April 21 at 0.29 au, inclination = 56.7 deg, eccentricity = 1.0

 

C/2021 O3 (PANSTARRS)                                             Max El
                                                                  (deg)
    Date      R.A.   Decl.     r       d    Elong  Const  Mag   40N  40S
2021-Aug-01  23 24  +27 58   4.251   3.655   119M   Peg  18.9    78   22
2021-Aug-06  23 21  +28 04   4.194   3.541   124M   Peg  18.8    78   22
2021-Aug-11  23 18  +28 06   4.137   3.431   128M   Peg  18.7    78   22
2021-Aug-16  23 14  +28 02   4.079   3.326   132M   Peg  18.6    78   22
2021-Aug-21  23 10  +27 53   4.021   3.226   136M   Peg  18.5    78   22
2021-Aug-26  23 05  +27 39   3.962   3.132   140M   Peg  18.4    78   22
2021-Aug-31  23 00  +27 18   3.903   3.045   143M   Peg  18.2    77   23
2021-Sep-05  22 54  +26 50   3.843   2.964   146E   Peg  18.1    77   23
Comet Magnitude Parameters --- H = 11.1, 2.5n = 8.0

 

MPEC 2021-P05 and CBET 5009 reported the discovery of a new comet by the Pan-STARRS survey. C/2021 O3 (PANSTARRS) was first seen on July 26 at 19th magnitude by the Pan-STARRS1 1.8-m Ritchey-Chretien on Haleakala. Though currently 4.2 au from the Sun, C/2021 O3 will get a lot closer to the Sun at perihelion. With an observational arc of only 6-days, the comet appears to be a long-period comet though it will be some weeks (unless pre-discovery observations are found) before we know whether it is dynamically old or new.

 

The current orbit by Syuichi Nakano has perihelion on 2022 April 21 at 0.29 au [CBET 5009]. At the present, we don’t have any information on this comet’s brightening rate. Any prediction of C/2021 O3’s brightness near perihelion will be very uncertain. Not to mention, whether the comet will even survive to reach perihelion.

 

C/2021 O3 will experience some of the same observational issues as C/2021 A1 (Leonard). On the plus side, PANSTARRS will reach a relatively large phase angle though not as large as Leonard (only ~136 vs 160 deg). PANSTARRS will also be located at very small solar elongation near perihelion which will make it a VERY difficult object to observe until a few weeks after perihelion and then only for northern observers.

 

This month, the comet is riding high in Pegasus near opposition for northern observers, but not too far north so southern observers will also be able to observe it. Though by observe, we mean imaging as the comet is expected to be around 18-19th magnitude this month.

 

Southern hemisphere observers should be able to follow PANSTARRS will near the end of the year when the comet could be around 15-16th magnitude. Northern hemisphere observers will be able to follow it for another month or two till mid-February when it could be as bright as 13-14th magnitude.  The comet will then spend the next two and a half months within 20 deg of the Sun.

 

The comet’s orbit will be refined over the coming weeks so we may still see its date of perihelion shift by a day or two. The analysis the follows is based on the current orbit with perihelion on 2022 April 21.26 UT at 0.297 au from the Sun and assumes the comet will not disintegrate. If it turns out to be dynamically new, its current brightness suggests an intrinsically faint object that may be prone to disintegration.

 

The comet’s orbit is aligned in such a way that the comet will be mainly a northern hemisphere object except for a week or so centered on perihelion. On the date of perihelion C/2021 O3 will be an evening object located only 16 deg from the Sun. Northern hemisphere observers (for +40N) will not be able to observe it at that time as it will still be 7 deg below the horizon at the start of nautical twilight. It will be observable from the southern hemisphere (-40S) when it will be at an elevation of 5 deg at the start of nautical twilight and only 1 deg below the horizon at the start of astronomical twilight. If the comet brightens at a 10log® from now till perihelion, it could be a magnitude 4.3 object. If its rate of brightening is 8log®, it will be fainter at magnitude 6.6. Either way this will be a difficult observation.

 

The comet becomes observable in a dark sky (after the end of astronomical twilight) by the first few nights of May. This is around the time of maximum phase angle (135 deg) which may provide a 1-2 magnitude boost in brightness. Still, we are talking about an object that may only be around 3rd-6th magnitude and still located ~20 deg from the Sun. Though it will be fading fast, the comet will quickly move north and circumpolar by mid-May.

 

Like C/Leonard, we still have some time to watch and wait. Imagers are highly encouraged to observe PANSTARRS over the coming months.

 

New Discoveries, Recoveries and Other Comets in the News

 

C/2021 O3 (PANSTARRS) – See above.

 

P/2021 O2 = P/2005 W3 (Kowalski) – This returning comet was a Catalina Sky Survey discovery by Richard Kowalski. At its 2005 apparition it peaked at 18th magnitude. The Pan-STARRS survey serendipitously recovered the comet on July 20th of this year at 20th magnitude. Rob Weryk (University of Western Ontario) then found Pan-STARRS observations 6 nights in 2020 going back to 2020 August 19. This year perihelion occurs on 2021 September 20 at 2.89 au. If the comet follows the same brightness trend as it did in 2005, it should peak at 17th magnitude. [Ref: CBET 5006]

 

C/2021 O1 (Nishimura) – See above.

 

C/2021 N3 (PANSTARRS) – The Pan-STARRS survey discovered this new long-period comet at 20th magnitude on July 13 with the Pan-STARRS1 1.8-m on Haleakala. The comet has already passed perihelion (T = 2020 August 19, q = 5.72 au) and will likely slowly fade from here on out. [Ref: MPEC 2021-O39, CBET 5003]

 

P/2021 N2 (Fuls) – David Carson Fuls found this 18th magnitude comet on July 9 with the 0.68-m Catalina Schmidt. P/2021 N2 is a short-period comet with an orbital period of 19.58-years. Perihelion is on 2021 October 29 at 3.82 au. A peak brightness around 17th magnitude is expected in November when the comet will be at opposition and still within weeks of perihelion. [Ref: MPEC 2021-N137, CBET 5000!]

 

P/2021 N1 (ZTF) – The Palomar 1.2-m Schmidt was used by the Zwicky Transient Facility survey to find this comet on July 2 at 19th magnitude. Pre-discovery observations from June 17th show the comet to have been brighter at 17th magnitude. P/2021 N1 is a short-period comet with a 5.12-year orbital period and small perihelion distance of 0.96 au. The comet is now fading as perihelion was back on 2021 June 6. [Ref: MPEC 2021-N115, CBET 4999]

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 the Comets Section < comets @ alpo-astronomy .org >, Comets Section Coordinator Carl Hergenrother < carl.hergenrother @ alpo-astronomy .org > and/or Comets Section Acting Assistant Coordinator Michel Deconinck < michel.deconinck @ alpo-astronomy .org >.

 

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

 

Stay safe and enjoy the sky!
- Carl Hergenrother


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