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ALPO Comet News for August 2020

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#1 Carl H.

Carl H.

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Posted 05 August 2020 - 06:58 PM

ALPO COMET NEWS FOR AUGUST 2020
A Publication of the Comet Section of the Association of Lunar and Planetary Observers
By Carl Hergenrother - 2020-August-5

 

The monthly Association of Lunar and Planetary Observers (ALPO) Comet News PDF can be found on the ALPO Comet 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.

 

C/2020 F3 (NEOWISE) was the celestial highlight of July and likely the best comet of 2020. NEOWISE is now rapidly fading but still a visually and photographically impressive object well placed for observation in the evening sky. August will see it fade from around 6th to 9th magnitude. By the end of August, short-period comet 88P/Howell will challenge NEOWISE’s place as the “brightest comet in the sky”. 2P/Encke, C/2017 T2 (PANSTARRS), and C/2019 U6 (Lemmon) start the month around 9-10th magnitude but fade throughout the month.

 

Almost 200 images and sketches of NEOWISE were submitted to the ALPO in July. Rather than include them all in this report, you can visit the Comet Section Image Gallery to see all of the NEOWISE images at
http://www.alpo-astr...nd-Observations .

 

 

Bright Comets (magnitude < 10.0)

 

C/2020 F3 (NEOWISE) – After throwing us a few head fakes, 2020 finally delivered a really good comet as C/2020 F3 (NEOWISE) developed into the breakout hit of July. After peaking around magnitude 1.5 in the days around its July 3rd perihelion at 0.29 au, the comet proceeded to put on a good show for both visual and imaging observers. Around the time of its July 23rd closest approach to Earth (0.69 au), dust and ion tails as long as ~10 and ~30 degrees where being imaged.

 

Now in full retreat from the Sun and Earth, NEOWISE is rapidly fading. Visual observations have placed the comet between magnitude 5.5 and 6.0 during the first few days of August. This month the comet is an evening object moving through Coma Berenices (Aug 1-9), Virgo (9-12), Boötes (12-15), and back into Virgo (15-31). The comet should fade to around magnitude 7 by the August 13, magnitude 8 by the 21st, and magnitude 9 by month’s end. NEOWISE will pass close to the globular cluster M53 late on August 5 UT.

 

C/2020 F3 (NEOWISE)
T = 2020-Jul-03  q = 0.29 au                                      Max El
Dynamically old long period comet                                  (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-08-01   5.2   12 32  +27 34   0.827   0.794    52    Com    27   13
2020-08-06   6.0   13 08  +19 00   0.933   0.913    57    Com    27   21
2020-08-11   6.8   13 32  +12 20   1.035   1.054    60    Vir    25   27
2020-08-16   7.4   13 49  +07 11   1.135   1.206    60    Vir    23   30
2020-08-21   8.1   14 02  +03 11   1.232   1.364    60    Vir    21   32
2020-08-26   8.6   14 13  -00 02   1.326   1.524    58    Vir    19   33
2020-08-31   9.1   14 22  -02 39   1.418   1.684    57    Vir    17   32
2020-09-05   9.6   14 31  -04 50   1.507   1.843    54    Vir    15   31             
Comet Magnitude Parameters --- H = 6.5, 2.5n = 9.8

 

C/2019 U6 (Lemmon) – C/2019 U6 (Lemmon) was discovered by Rich Kowalski (University of Arizona) on October 31 with the Mount Lemmon Survey’s 1.5-m reflector. At discovery, Lemmon showed no evidence of cometary activity. Since then, it rapidly brightened to a peak around magnitude 6.5 near the time of its mid-June perihelion at 0.91 au. Since then the comet has faded more rapidly than expected. In fact, its lightcurve is best fit if its peak activity is offset ~12 days prior to perihelion. Perhaps the comet has one or a few active areas that were at peak illumination or heating just before perihelion causing a seasonal effect. The most recent observations placed Lemmon at magnitude 9.0 on July 27.92 (Willian Souza), 9.3 on July 30.35 (Chris Wyatt), and 10.2: on August 5.35 UT (Chris Wyatt).

 

This month Lemmon is visible from both hemispheres in the evening sky as it moves through Coma Berenices (Aug 1-3) and Boötes (3-31). Starting the month around magnitude 9.5-10.0 it may fade to magnitude 12 by the end of the month.

 

C/2019 U6 (Lemmon)
T = 2020-Jun-18  q = 0.91 au                                      Max El
Dynamically old long period comet                                  (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S
2020-08-01   9.5   13 26  +17 15   1.187   1.145    66    Com    31   27 
2020-08-06   9.9   13 46  +18 44   1.241   1.225    66    Boo    34   26 
2020-08-11  10.3   14 05  +19 53   1.298   1.307    66    Boo    36   24 
2020-08-16  10.8   14 22  +20 47   1.357   1.391    66    Boo    38   23
2020-08-21  11.2   14 38  +21 28   1.417   1.475    66    Boo    39   21
2020-08-26  11.5   14 53  +21 58   1.479   1.560    66    Boo    40   20
2020-08-31  11.9   15 08  +22 20   1.541   1.646    65    Boo    41   18
2020-09-05  12.3   15 21  +22 36   1.603   1.731    65    Ser    42   17   
Comet Magnitude Parameters --- H = 7.3, 2.5n = 15.5, Offset = -12 days

 

88P/Howell – Short-period comet 88P/Howell is making its 9th observed return. 88P was discovered in August 1981 and has been observed at every return since then. The comet’s perihelion distance has gradually fallen from 1.62 au in 1981 to its current 1.35 au. The lower perihelion distance has resulted in Howell often peaking at brighter than 10th magnitude. 88P comes to perihelion next month on September 28 and should peak around 8-9th magnitude.

 

The most recent estimates place P/Howell around magnitude 10 (10.4 on August 5.37 UT – Chris Wyatt, 10.3 on July 30.37 UT – Chris Wyatt, and 10.1 on July 24.91 UT – J. J. Gonzalez). This month, 88P moves through Virgo (Aug 1-16) and Libra (16-31) as it brightens from 10th to 9th magnitude. It is possible it could be the brightest comet in the sky by the end of August.

 

88P/Howell was the target of the proposed Comet Rendezvous, Sample Acquisition, Investigation, and Return (CORSAIR) mission. In 2017, CORSAIR was proposed to the NASA New Frontiers program but was ultimately not selected. The Dragonfly mission to Titan was the eventual winner of the 2017 New Frontiers call for proposals.

 

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

2020-08-01  10.2   13 45  -12 14   1.488   1.281    79    Vir    15   56
2020-08-06  10.0   13 56  -13 29   1.467   1.291    77    Vir    14   55
2020-08-11   9.9   14 07  -14 45   1.447   1.301    76    Vir    13   54
2020-08-16   9.7   14 20  -16 02   1.429   1.311    74    Vir    12   53
2020-08-21   9.6   14 33  -17 19   1.412   1.320    73    Lib    12   53
2020-08-26   9.4   14 46  -18 36   1.398   1.329    71    Lib    11   52
2020-08-31   9.3   15 01  -19 51   1.385   1.338    70    Lib    11   51
2020-09-05   9.3   15 16  -21 03   1.374   1.348    69    Lib    11   50       
Comet Magnitude Parameters --- H = 3.7, 2.5n = 34.1

 

Fainter Comets of Interest (fainter than magnitude 10.0)


 

2P/Encke – Comet Encke has the shortest known orbital period of any comet (not counting asteroidal objects that appear cometary due to impacts or rotational splitting) at 3.3 years. 2020 marks Encke’s 65th observed return since 1786. Perihelion occurred on June 26 at 0.34 au. Northern summer/southern winter returns of Encke result in very poor placement pre-perihelion and then good placement after perihelion but only for southern hemisphere observers.

 

Willian Souza estimated Encke at magnitude 9.0 on July 27.92 while Chris Wyatt placed it fainter at magnitude 10.5 on August 5.36 UT. Encke should continue to rapidly fade past 13th magnitude by mid-month. August sees the comet moving through the evening constellations of Corvus (Aug 1-6), Hydra (6-19), Centaurus (19-21), and Lupus (21-31).

 

IN 2020 Encke has been fading at a slower rate (2.5n = 10.1) than predicted by Seiichi Yoshida based on past apparitions (2.5n = 15.7). If the later rate is correct, the comet will be fainter than in the prediction below.

 

2P/Encke

T = 2020-Jun-26  q = 0.34 au                                      Max El
Jupiter-family comet                                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S
2020-08-01  10.5   12 07  -17 14   0.896   0.624    60    Cor     0   44
2020-08-06  11.2   12 54  -22 22   0.981   0.645    68    Cor     0   51
2020-08-11  11.9   13 39  -26 13   1.063   0.687    74    Hyd     0   57
2020-08-16  12.6   14 20  -28 50   1.142   0.747    79    Hyd     3   62
2020-08-21  13.2   14 57  -30 27   1.219   0.821    82    Cen     5   65
2020-08-26  13.8   15 29  -31 20   1.294   0.904    84    Lup     7   67
2020-08-31  14.4   15 56  -31 44   1.366   0.996    85    Lup     9   68
2020-09-05  15.0   16 20  -31 50   1.435   1.093    86    Lup    10   68
Comet Magnitude Parameters - H = 11.6, 2.5n = 10.1

 

C/2017 T2 (PANSTARRS) – For the past 8 months, C/2017 T2 (PANSTARRS) has been brighter than 10th magnitude as it leisurely traversed the northern evening sky. Now 3 months past its early May perihelion at 1.62 au, PANSTARRS will likely fade back below 10th magnitude. Between July 19 and 24, visual observations by J. J. Gonzalez and Chris Wyatt placed PANSTARRS between magnitude 9.6 and 10.4. This month PANSTARRS’ path somewhat parallels NEOWISE’s though PANSTARRS will be moving more slowly. It moves to the southeast through the evening constellations of Coma Berenices (Aug 1-6), Boötes (6-23), and Virgo (23-31).

 

C/2017 T2 (PANSTARRS)

T = 2020-May-04  q = 1.62 au                                      Max El
Long-Period comet - dynamically new                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-08-01  10.3   13 27  +19 34   1.993   2.175    66    Com    33   25 
2020-08-06  10.5   13 35  +16 34   2.031   2.254    64    Com    30   26 
2020-08-11  10.7   13 42  +13 44   2.070   2.336    62    Boo    28   27
2020-08-16  10.9   13 50  +11 04   2.110   2.422    60    Boo    26   27
2020-08-21  11.1   13 57  +08 32   2.151   2.509    57    Boo    23   27
2020-08-26  11.3   14 04  +06 10   2.193   2.599    55    Vir    21   26
2020-08-31  11.5   14 11  +03 55   2.236   2.689    53    Vir    19   25
2020-09-05  11.6   14 18  +01 49   2.279   2.780    50    Vir    17   24 
            Comet Magnitude Parameters --- H = 4.6, 2.5n = 13.5

 

New Discoveries, Recoveries and Other Comets in the News

 

P/2020 O3 (PANSTARRS) – This 20th magnitude comet was found on July 28 by the Pan-STARRS1 1.8-m reflector on Haleakala. P/2020 O3 is a short-period comet with a 10.1-year period and perihelion back on 2020 December 22 at 4.18 au. The comet has likely peaked in brightness.

 

C/2020 O2 (Amaral) – Leonardo S. Amaral of Rio de Janeiro, Brazil discovered this 18th magnitude comet with a 0.3-m f/4 reflector at the Observatório Campo dos Amarais (OCA). This is the first comet discovery by the OCA which has also discovered 3 near-Earth asteroids. C/2020 O2 is about 1 year out from a perihelion at 4.90 au on 2021 August 23. Currently located at a southern declination of -51 degrees, the comet is slowly moving north and will be observable from both hemispheres when it is at its brightest (16th magnitude) in mid-2021.

 

P/2020 O1 (Lemmon-PANSTARRS) – This object is an “Active Asteroid” or “Main Belt Comet”. It was reported as a 19th magnitude comet discovery from images taken on July 20 UT with the Pan-STARRS1 telescope. One night earlier, the object was reported as an asteroid by the Mount Lemmon Survey using the Mount Lemmon 1.5-m. The object has a very asteroidal orbit with semi-major axis of 2.65 au, eccentricity of 0.12, and inclination of 5.2 degrees. Perihelion was on 2020 May 3 at 2.33 au. The mechanism responsible for its recent activity (i.e. impact, rotational disruption, ice sublimation) is still TBD.

 

C/2020 N2 (ATLAS) – The "Asteroid Terrestrial-Impact Last Alert System" or ATLAS program discovered C/2020 N2 on 2020 July 13 at 18th magnitude with their 0.5-m f/2 Schmidt reflector at Mauna Loa. With perihelion coming this month (August 23) at 1.80 au, C/2020 N2 is unlikely to get much brighter than 17th magnitude.

 

C/2020 N1 (PANSTARRS) – The Pan-STARRS1 telescope on Haleakala, Hawaii found this 21st magnitude object on July 3. Perihelion occurs on 2021 March 12 at 1.32 au. Unfortunately, this comet will never get closer than 1.2 au to Earth. If it brightens at a 2.5n = 8 rate, it will brighten to 14th magnitude. If it brightens at 2.5n = 10, it would reach 13th magnitude. This is one to keep an eye on if it brightens at a more rapid rate.

 

C/2020 M5 (ATLAS) – ATLAS found C/2020 M5 on June 30 at 19th magnitude. Numerous pre-discovery observations by Pan-STARRS were found back to August 2019 when the comet was at 23rd magnitude. Perihelion is still over a year out on 2021 August 19 at 3.00 au when the comet should be at 15th magnitude.

 

A/2020 M4 – This apparently asteroidal object was found by Pan-STARRS on June 17 at 22nd magnitude. It comes to perihelion on 2020 November 23 at 5.95 au and is unlikely to get brighter.

 

2020 MK4 – Yet another apparently asteroidal Pan-STARRS discovery, 2020 MK4 was found on June 16 at 22nd magnitude. Perihelion was back on 2020 April 11 at 2.54 au. It is has also likely peaked in brightness. Its current orbit has an orbital period of ~400 years.

 

2020 ML1 – 2020 ML1 is on a nearly circular Centaur-type orbit just outside the orbit of Jupiter. With a very small eccentricity of 0.017, its orbit only ranges from a perihelion of 6.03 au to an aphelion of 6.25 au. Like the previous two objects, ML1 was also a Pan-STARRS find. It was first seen on June 16 at 21st-22nd magnitude.

 

C/2019 Y5 (PANSTARRS) – This object was discovered by Pan-STARRS on 2019 December 28 at 21st magnitude. Pre-discovery observations were found by Pan-STARRS back to 2019 September 11. Even though the object was reported as cometary by Pan-STARRS with a 1.9’ coma and 6” long tail, it was announced as an asteroidal object with the designation A/2019 Y5. Since then numerous other observers have confirmed its cometary nature resulting in a re-designation as C/2019 Y5 (PANSTARRS). It is a dynamically old long-period comet with perihelion back on 2019 August 18 at 4.91 au. The comet is now slowly fading.

 

C/2019 O3 (Palomar) – Here’s another object that was classified as an asteroid at discovery. This time cometary activity was not noticed at discovery. This object was originally designated as A/2019 O3 when after discovery with the 1.2-m Oschin schimidt on Mount Palomar on 2019 July 26 at 19th magnitude. Numerous recent reports of its cometary nature were reported on CBET 4817 leading to its re-designation as C/2019 O3 (Palomar). The comet is currently 18th magnitude but is not expected to get much brighter as it approaches a distant perihelion on 2021 March 7 at 8.82 au.

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 Comet Section!

 

Stay safe and enjoy the sky!
- Carl Hergenrother (ALPO Comet Section Coordinator)


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#2 Carl H.

Carl H.

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Posted 08 August 2020 - 04:05 PM

Discovery of C/2020 P1 (NEOWISE), another small-q comet!

 

The Minor Planet Center and Central Bureau of Astronomical Telegrams announced the discovery of a new small perihelion NEOWISE comet. I don't blame you if you're feeling a sense of deja vu. Again we have a faint NEOWISE comet discovered deep in the southern sky headed for a perihelion around 0.3 au from the Sun.

 

Here's what we know. The new comet, C/2020 P1 (NEOWISE), was discovered on August 2/3 with perihelion occurring on October 20 at 0.34 au. As was the case with F3, P1 will only be visible from the southern hemisphere until a week or so before perihelion when no one on Earth will be able to see it, and then it reappears around perihelion but only from the northern hemisphere.

 

The brightest observation reported so far places the comet at magnitude 15.5 which is ~5 magnitudes fainter than F3 was at the same heliocentric distance. That's not a good sign. The magnitudes given below assume a conservative 2.5n = 8 brightening rate and sees a peak brightness of only 9th magnitude. If true, then this object should be kept on 'fizzle' watch. Then again we were saying the same thing with regards to F3. Can lightning strike twice? Unlikely, but we'll see.

 

C/2020 P1 (NEOWISE)
T = 2020-Oct-20  q = 0.34 au                                      Max El
Long period comet                                                 (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S
2020-08-11  15.7   12 32  -72 14   1.599   1.187    92    Mus     0   49
2020-08-16  15.5   12 49  -69 42   1.513   1.156    88    Mus     0   47
2020-08-21  15.3   12 02  -67 12   1.425   1.125    83    Mus     0   45
2020-08-26  15.0   12 13  -64 46   1.336   1.092    78    Mus     0   43
2020-08-31  14.7   12 22  -62 21   1.244   1.057    73    Cru     0   40
2020-09-05  14.4   12 25  -59 56   1.150   1.019    69    Cru     0   36            

2020-09-10  13.6   12 26  -57 25   1.054   0.977    64    Cru     0   33

2020-09-15  13.2   12 28  -54 43   0.955   0.930    58    Cen     0   29

2020-09-20  12.7   12 29  -51 39   0.854   0.879    53    Cen     0   24

2020-09-25  12.1   12 30  -47 55   0.752   0.823    47    Cen     0   19

2020-09-30  11.4   12 31  -43 04   0.648   0.764    40    Cen     0   12

2020-10-05  10.6   12 32  -36 21   0.545   0.707    31    Cen     0    6

2020-10-10   9.8   12 33  -26 53   0.450   0.666    21    Hya     0    1

2020-10-15   9.2   12 38  -14 39   0.374   0.665    12    Crv     0    0

2020-10-20   9.1   12 50  -02 33   0.343   0.731    14    Vir     0    0

2020-10-25   9.7   13 08  +05 17   0.370   0.856    21    Vir     3    0

2020-10-30  10.7   13 28  +08 44   0.443   1.001    25    Vir     6    0

          Comet Magnitude Parameters --- H = 13.5, 2.5n = 8.0


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#3 Carl H.

Carl H.

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Posted 26 August 2020 - 05:56 PM

C/2020 M3 (ATLAS) brighter than expected!

 

C/2020 M3 (ATLAS) was discovered on June 27 by the ATLAS program with their 0.5-m f/2 astrograph on Mauna Loa. At the time, the comet was only 19th magnitude. Yesterday CBET 4838 published a new orbit with a period of 138 years and a recent observation by K. Yoshimoto which placed M3 at magnitude 12.8 (Aug. 24.7 UT). After reading the CBET, I quickly observed the comet with the iTelescope T12 0.11-m refractor and measured the comet at magnitude V = 11.2 and R = 14.5 (Aug. 25.8 UT). In the Green filter, the comet's coma was 9.3'. In the Red, it was much smaller at 1.8'. The large difference between Green (V) and Red ® suggests a very dust-poor or gas-rich object.

 

Perihelion is almost 2 months away at 1.27 au on October 25 with close approach to Earth occurring a few weeks later at 0.36 au on November 15. It is possible that M3 may become a small telescope/binocular object in the coming weeks and remain so through the end of the year. Currently a southern object in the morning sky, it will be easily observable from both hemispheres by October. 

 

C/2020 M3 (ATLAS)
T = 2020-Oct-15  q = 1.27 au                                      Max El
Long period comet                                                 (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020- 8-27  11.1   02 45  -36 21   1.539   0.804   115    For    12   85
2020- 9-06  10.7   03 14  -36 21   1.463   0.718   114    For    13   85
2020- 9-16  10.2   03 42  -35 34   1.397   0.641   114    For    14   84
2020- 9-26   9.8   04 09  -33 43   1.342   0.571   114    Eri    15   83
2020-10-06   9.4   04 33  -30 24   1.301   0.508   115    Eri    19   79
2020-10-16   9.1   04 53  -25 14   1.276   0.451   118    Eri    24   74
2020-10-26   8.8   05 09  -17 39   1.268   0.404   124    Lep    32   66
2020-11-05   8.6   05 20  -07 20   1.278   0.370   134    Ori    42   56
2020-11-15   8.7   05 26  +05 15   1.304   0.358   146    Ori    55   43
2020-11-25   8.9   05 26  +18 20   1.346   0.375   160    Tau    68   30
2020-12-05   9.3   05 23  +29 35   1.401   0.421   169    Aur    79   19
2020-12-15   9.9   05 18  +37 47   1.469   0.495   165    Aur    87   11

2020-12-25  10.5   05 14  +43 06   1.545   0.592   156    Aur    88    6

          Comet Magnitude Parameters --- H = 9.74, 2.5n = 10.0


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