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[Carl H.]

ALPO COMET NEWS FOR MAY 2020
A Publication of the Comet Section of the Association of Lunar and Planetary Observers
By Carl Hergenrother - 2020-May-1
 


 

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, images, 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.

 

Most of us comet watchers may all be in lockdown, but the heavens are giving us plenty to watch. Recent discoveries have produced a number of reasonably bright comets to observe. As many as 6 comets should be brighter than 10th magnitude this May. The brightest is C/2020 F8 (SWAN). After a recent outburst at the end of April, SWAN is currently around 5th magnitude and a borderline naked eye object for observers in the southern hemisphere. Southern observers will also be able to watch C/2019 U6 (Lemmon) brighten to 7th magnitude and C/2020 F3 (NEOWISE) brighten to 8th magnitude. Northern observers have their own collection of bright objects to observe including C/2017 T2 (PANSTARRS), C/2019 Y1 (ATLAS), and the disintegrating remains of C/2019 Y4 (ATLAS). If it remains a bright object, C/2020 F8 (SWAN) may also be visible, with difficulty, from the northern hemisphere later in the month. As if the above weren’t interesting enough, a number of slightly fainter but still interesting comets can be observed just fainter than 10th magnitude.

 

Naked Eye Comets (magnitude < 5.0)

 

C/2020 F8 (SWAN) –Australian amateur astronomer Michael Mattiazzo reported a possible comet candidate in SOHO SWAN data taken between March 26 and April 7. The SWAN (Solar Wind Anisotropies) instrument covers much of the sky, albeit at a low resolution, and is sensitive to ultraviolet wavelengths making it an excellent detector of emissions from cometary hydrogen. Fourteen comets now bear the SWAN name and Mattiazzo was involved in the discovery of 8 of them.

 

Comet SWAN appeared to be in outburst as it rapidly brightening in the SWAN data. By April 11.73 UT, ALPO contributor Christopher Wyatt was estimating the comet at magnitude 8.0. Over the next two weeks, the comet brightened by a full magnitude with ALPO contributor Willian Souza reporting it at 7.0 on April 25.35. But the brightening was somewhat misleading as the comet was in fact fading, or producing less gas and dust, over that time span. The apparent brightening was only the result of decreasing comet-Sun (1.14 to 0.92 au) and comet-Earth (1.32 to 0.95 au) ranges. Most likely, the comet was settling down from the outburst that led to its discovery. A second outburst occurred around April 26. By April 29 and 30, Christopher Wyatt and Willian Souza were reporting the comet to be between magnitudes 5.1 and 5.4. CCD images have also been reporting a dynamic ion tail over 10 degrees in length.

 

SWAN’s future behavior is uncertain. Extrapolating the comet’s current brightness with an assumed 2.5n = 7.5 photometric parameter results in a peak brightness of ~3.3 in the week before its May 27 perihelion at 0.43 au. The comet could get even brighter due to some enhancement from forward scattering by dust and if it experiences another outburst. Then again, it is also possible the comet will slow its current brightening or even fade as its recent outburst ends.

 

CCD images of the comet have often shown a hint of a coma morphological feature called coma arclets, or “coma wings”, which are associated with splitting events. If the comet’s nucleus is splitting, it would explain its recent outbursts. Splitting events don’t mean SWAN will disintegrate (like C/2019 Y4), but it does raise that possibility. If SWAN were to disintegrate, it could be a much fainter object at it approaches perihelion. 

 

SWAN begins May as a southern hemisphere only object but is racing northwards through Cetus (May 1-8), Pisces (8-14), Triangulum (14-18), Perseus (18-29), and Auriga (29-31). While it will be visible to northerners by mid-month, it will be a horizon hugging object quickly moving along the eastern to northeastern horizon. Even if the comet becomes as bright as 3rd magnitude, it will maybe difficult to see against a rapidly brightening dawn sky.

 

C/2020 F8 (SWAN)

T = 2020-May-27  q = 0.43 au                                      Max El
Long-Period comet                                                 (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01   5.1?  23 58  -17 12   0.779   0.743    50    Cet     0   32
2020-05-06   4.4?  00 27  -05 13   0.687   0.626    42    Cet     0   22
2020-05-11   3.7?  01 08  +11 28   0.600   0.561    30    Psc     0    7
2020-05-16   3.3?  02 06  +29 20   0.521   0.580    22    Tri     3    0
2020-05-21   3.3?  03 14  +41 32   0.462   0.689    22    Per     4    0
2020-05-26   3.5?  04 16  +46 09   0.433   0.857    25    Per     4    0
2020-05-31   4.1?  05 00  +46 02   0.443   1.048    24    Aur     6    0
2020-06-05   4.7?  05 26  +43 57   0.489   1.235    22    Aur     4    0
            Comet Magnitude Parameters --- H = 6.6, 2.5n = 7.5

 

Bright Comets (magnitude < 10.0)

 

C/2017 T2 (PANSTARRS) – With most northern eyes on C/2019 Y1 and Y4, C2017 T2 (PANSTARRS) has become a bit of a forgotten comet. C/2017 T2 has been a consistent fixture in the northern evening sky even if it has lacked the outbursts and disintegrations of the ATLAS comets.

 

Comet PANSTARRS has been bright enough to be seen visually in small apertures since late last year. Perihelion finally occurs on May 4th at 1.62 au. During April, visual observations by ALPO contributors Michel Deconinck and Carl Hergenrother placed it between magnitude 8.2 and 8.6. May should see more of the same as the comet continues to move through the northern circumpolar constellations of Camelopardalis (May 1-18) and Ursa Major (18-31). On May 25th, we pass through the comet’s orbital plane so CCD imagers should be on the lookout for some interesting tail features at that time. 

 

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

2020-05-01   8.3   06 17  +76 16   1.616   1.705    67    Cam    43    0
2020-05-06   8.3   07 13  +76 13   1.615   1.692    68    Cam    44    0
2020-05-11   8.3   08 10  +75 24   1.617   1.680    68    Cam    46    0
2020-05-16   8.3   09 01  +73 49   1.622   1.670    69    Cam    48    0
2020-05-21   8.3   09 44  +71 33   1.630   1.663    70    UMa    51    0
2020-05-26   8.3   10 20  +68 46   1.640   1.659    71    UMa    52    0
2020-05-31   8.4   10 49  +65 33   1.653   1.660    71    UMa    54    0
2020-06-05   8.4   11 12  +62 02   1.669   1.666    72    UMa    55    0
            Comet Magnitude Parameters --- H = 5.1, 2.5n = 10.0

 

C/2019 U6 (Lemmon) – This comet has been flying a bit under the radar. C/2019 U6 was discovered on October 31 with the University of Arizona’s 1.5-m Mount Lemmon reflector. At the time the object was designated with the A/ prefix but subsequently observed cometary activity resulted in the object being rebranded as comet C/2019 U6 (Lemmon).

 

At discovery, C/2019 U6 was 20th magnitude. As recently as February, CCD imagers were reporting it at 16-17th magnitude. During April, Christopher Wyatt observed Lemmon as it brightened from 10.5 (April 11.39) to 9.3 (April 25.37). His March and April observations are consistent with a very rapid brightening rate of 2.5n ~ 24. While it is likely the brightening trend will slow down, the good news is C/2019 U6 could brighten to 6-7th magnitude even when assuming a more mundane 2.5n = 7.5 rate from now till perihelion on June 18 at 0.91 au. This month Lemmon should brighten from 9th to 7th magnitude as an evening object moving through Lepus (May 1-20) and Canis Major (20-31). The comet is currently only a southern hemisphere object. Northern observers will have to wait till early July when it should still be close to its maximum brightness.

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

2020-05-01   8.9   05 12  -22 16   1.249   1.542    53    Lep     0   36
2020-05-06   8.6   05 25  -22 04   1.194   1.472    53    Lep     0   36
2020-05-11   8.4   05 40  -21 50   1.141   1.399    53    Lep     0   36
2020-05-16   8.1   05 56  -21 32   1.092   1.323    53    Lep     0   36
2020-05-21   7.8   06 15  -21 06   1.048   1.245    54    CMa     0   36
2020-05-26   7.6   06 36  -20 29   1.008   1.168    54    CMa     0   36
2020-05-31   7.3   07 00  -19 36   0.974   1.092    54    CMa     0   37
2020-06-05   7.1   07 27  -18 18   0.947   1.020    55    CMa     0   38
            Comet Magnitude Parameters --- H = 7.2, 2.5n = 7.5

 

C/2019 Y1 (ATLAS) – While C/2019 Y4 (ATLAS) got most of the attention, it wasn’t the only C/2019 Y# (ATLAS) comet visible to northern hemisphere observers. In fact, for much of April C/2019 Y1 was brighter than the infamous Y4.

 

C/2019 Y1 was at perihelion on 2020 March 15 at 0.84 au. It appears to be the 4th member of a comet family associated with C/1988 A1 (Liller), C/1996 Q1 (Tabur), and C/2005 F3 (SWAN). After spending March hugging the western evening horizon, C/2019 Y1 worked its way higher into the northwestern sky. An outburst occurred around mid-month resulting in an increase in brightness from magnitude 8.5 to 7.5. The comet has since settled back down to somewhere between 8.0 and 8.5. This month the comet will climb even higher for northern observers as it moves through Cepheus (May 1-2), Camelopardalis (2-8), Draco (8-12), and Ursa Major (12-31).

 

C/2019 Y1 (ATLAS)

T = 2020-Mar-15  q = 0.83 au                                     Max El
Long-Period comet - dynamically old                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01   8.4   04 27  +82 12   1.187   1.106    68    Cep    38    0
2020-05-06   8.6   08 11  +81 09   1.248   1.109    72    Cam    45    0
2020-05-11   8.8   09 57  +75 19   1.311   1.127    75    Dra    52    0
2020-05-16   9.1   10 40  +68 28   1.375   1.160    78    UMa    58    0
2020-05-21   9.4   11 03  +61 40   1.440   1.209    80    UMa    62    0
2020-05-26   9.7   11 17  +55 13   1.506   1.272    81    UMa    64    0
2020-05-31  10.0   11 28  +49 17   1.572   1.348    82    UMa    63    1
2020-06-05  10.3   11 37  +43 53   1.638   1.434    82    UMa    60    6
            Comet Magnitude Parameters --- H = 7.4, 2.5n = 10.0

 

C/2019 Y4 (ATLAS) – Over the course of a few weeks, C/2019 Y4 went from just another faint NEO survey discovery to the ‘Comet of the Century’ to the ‘Great Comet Letdown of 2020’. After surprising the astronomical community by rapidly brightening from 19th to 8th magnitude, resulting in the aforementioned media hype, C/2019 Y4 surprised us again by disintegrating.

 

Last month we were wondering how bright ATLAS would get at perihelion, 0th magnitude or much, much fainter. We now have our answer, much, much fainter. After peaking around magnitude 8.0 in early April, the comet proceeded to start an intrinsic fading. As April progresses, the comet’s inner coma started to elongate and even displayed evidence of multiple components. This was highlighted by images taken with the Hubble Space Telescope showing over a dozen components.

 

As May begins, the comet appears as a very diffuse elongated object with dimensions on the order of ~3x8 arc minutes. My visual and CCD observations have placed the comet between 8.9 and 9.4 over the past 2 weeks. The comet is visible only from the northern hemisphere though it will disappear in the bright glow of dusk by mid-month as it moves through Camelopardalis (May 1-12), Perseus (12-26), and Taurus (26-31). The magnitudes given below are a complete SWAG and roughly follow the comet’s fading trend since early April. Even though C/2019 Y4 never became the nice comet we were hoping for, it has provided an excellent opportunity to watch the disintegration of a comet well placed for observation.

 

C/2019 Y4 (ATLAS)

T = 2020-May-31  q = 0.25 au                                     Max El
Long-Period comet - dynamically old - disintegrating              (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01   9.4?  05 18  +60 00   0.878   0.922    53    Cam    35    0
2020-05-06   9.4?  04 58  +57 23   0.766   0.890    47    Cam    28    0
2020-05-11   9.5?  04 39  +54 00   0.651   0.853    39    Cam    21    0
2020-05-16   9.6?  04 18  +49 19   0.532   0.816    31    Per    12    0
2020-05-21   9.8?  03 57  +42 24   0.412   0.786    22    Per     1    0
2020-05-26  10.1?  03 40  +32 14   0.304   0.789    13    Per     0    0
2020-05-31  10.5?  03 39  +20 07   0.253   0.868    12    Tau     0    0
2020-06-05  10.7?  03 58  +11 38   0.303   1.021    17    Tau     0    0
            Comet Magnitude Parameters --- H = 9.4, 2.5n = -2.4

 

C/2020 F3 (NEOWISE) – Another comet flying under the radar is C/2020 F3 (NEOWISE). Discovered by the NEOWISE, or Near-Earth Object Wide-field Infrared Survey Explorer, spacecraft on March 27, C/2020 F3 was a faint 15-16th magnitude object at discovery. It has since rapidly brightened to between magnitude 10.3 (Chris Wyatt, visual, April 25.38) and 10.5 (Carl Hergenrother, CCD, April 28.38).

 

It is well placed for southern hemisphere observers till early June when it will be too close to the Sun for all ground-based observers. This means the comet will not be visible for about a month prior to its July 3 perihelion (q = 0.29 au) though it may be visible in the SOHO LASCO field-of-view around the time of perihelion. The comet reappears for ground-based observers after perihelion in early to mid-July for the NH and late July for the SH.

 

This month the comet is an evening object in Lepus (May 1-18), Monoceros (18-28), and Orion (28-31). If it continues to brighten at its current rate, it could be brighter than the prediction below. Alternately, this is one to watch for signs of disintegration (on a completely different tangent, I find myself listening to The Cure’s Disintegration album as I type this).

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

2020-05-01  10.2   06 12  -23 13   1.514   1.621    65   10.2     0   48
2020-05-06  10.0   06 09  -19 38   1.425   1.623    60   10.0     0   43
2020-05-11   9.8   06 08  -16 07   1.333   1.626    54    9.8     0   38
2020-05-16   9.6   06 06  -12 41   1.239   1.627    49    9.6     0   32
2020-05-21   9.3   06 05  -09 19   1.142   1.625    44    9.3     0   27
2020-05-26   9.0   06 05  -05 58   1.043   1.620    38    9.0     0   21
2020-05-31   8.6   06 04  -02 35   0.941   1.609    33    8.6     0   16
2020-06-05   8.2   06 03  +00 53   0.835   1.590    27    8.2     0   10
            Comet Magnitude Parameters --- H = 7.8, 2.5n = 7.5

 

Fainter Comets of Interest (fainter than magnitude 10.0)


 

58P/Jackson-Neujmin - 58P/Jackson-Neujmin was discovered at 12th magnitude in September 1936 by Cyril Jackson (Union Observatory, South Africa, 3 comet discoveries) and Grigory Neujmin (Simeis Observatory, Crimea, 6 comet discoveries). Both observers were conducting independent photographic asteroid surveys.

 

This year, 58P arrives at perihelion on 2020 May 27 at 1.38 au. 2020 marks 58P's 6th observed return (1936, 1970, 1978, 1987, 1995, and 2020). It was not seen at returns in 1945, 1953, and 1962 and at its most recent returns in 2004 and 2012. 1995 was its most recent good return when the comet passed within 0.43 au of Earth and peaked around magnitude 10.0. The comet was very poorly placed for observation in 2012. While not well placed in 2004, it is surprising that it was not seen at that return.

 

As for this return, 58P is a distant 2.2 au from Earth and should have been a faint object. Visual observations by Chris Wyatt found the comet around magnitude 10.4-10.7 in late April. Obviously in outburst, the comet may fade rapidly this month as the outburst subsides. It is only visible from the southern hemisphere as it moves through Pisces (May 1-4), Cetus (4-5), and Pisces (5-31) in the morning sky.

 

58P/Jackson-Neujmin

T = 2020-May-27  q = 1.38 au                                     Max El
Jupiter-family comet                                              (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01  10.9?  00 16  +01 41   1.413   2.088    36    Vir     0   17
2020-05-06  10.7?  00 32  +02 51   1.401   2.066    37    Vir     0   17
2020-05-11  10.6?  00 49  +03 59   1.391   2.046    37    Vir     0   18
2020-05-16  10.5?  01 06  +05 06   1.384   2.029    38    Vir     0   18
2020-05-21  10.5?  01 23  +06 10   1.380   2.015    38    Vir     0   18
2020-05-26  10.5?  01 40  +07 11   1.378   2.003    39    Vir     0   19
2020-05-31  10.5?  01 57  +08 08   1.378   1.993    39    Vir     0   19
2020-06-05  10.5?  02 13  +09 01   1.381   1.985    40    Vir     0   19
            Comet Magnitude Parameters --- H = 5.5, 2.5n = 25.0

 

88P/Howell – Short-period comet 88P/Howell is making its 9th observed return. 88P was discovered on photographic plates taken with the 0.46-m Palomar Schmidt in August 1981 by then Caltech student, and currently my fellow University of Arizona OSIRIS-REx team member, Ellen Howell. In addition to being found in pre-discovery observations from 1955, 88P has been observed at every return since 1981. The comet’s perihelion distance has gradually fallen from 1.92 au in 1955, to 1.62 au in 1981, to 1.41 au in 1993 to its current 1.35 au. As a result, comet Howell now often peaks brighter than 10th magnitude. Its brightest return was in 2009 when it peaked at 8th magnitude. This year it comes to perihelion on September 28 and should again peak around 8-9th magnitude.

 

During April, Chris Wyatt spotted comet Howell between magnitude 14.2 and 14.8. This month, 88P will brighten from around magnitude 13.1 to 12.1 bringing it within range of large aperture visual observers. Its location in Virgo near the celestial equator makes it a good target for both hemispheres.

 

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

2020-05-01  13.5   12 57  -01 36   2.036   1.088   152    Vir    48   52
2020-05-06  13.2   12 52  -01 23   2.002   1.082   146    Vir    49   51
2020-05-11  13.0   12 48  -01 14   1.969   1.080   140    Vir    49   51
2020-05-16  12.7   12 44  -01 12   1.936   1.083   135    Vir    49   51
2020-05-21  12.5   12 41  -01 15   1.904   1.089   129    Vir    48   51
2020-05-26  12.3   12 40  -01 25   1.871   1.099   124    Vir    47   52
2020-05-31  12.1   12 39  -01 42   1.839   1.110   119    Vir    45   52
2020-06-05  11.8   12 39  -02 04   1.807   1.123   115    Vir    42   52
            Comet Magnitude Parameters --- H = 3.1, 2.5n = 33

 

210P/Christensen & 249P/LINEAR – These two objects are similar in that they are both short-period comets with perihelion distances of ~0.5 au and may not be comets in the traditional sense. While most comets originate in the Kuiper Belt or Oort Cloud, dynamical and spectral evidence suggests that some may originate closer to the inner solar system in the Main Belt. Both 210P and 249P have been flagged as possible escaped Main Belt comets. Unlike most comet nuclei which are red and resemble D-type asteroids. 249P’s nucleus is slightly blue and is classified as a B-type similar to the Geminid parent (3200) Phaethon and the OSIRIS-REx target (101955) Bennu.

 

Both objects are faint or inactive until they get within ~1-2 au of the Sun but can be borderline visual objects at perihelion. 210P was discovered by Eric Christensen of the Catalina Sky Survey in May 2003 with the 0.7-m Catalina Schmidt. A month prior, X.-m. Zhou had detected the comet in SOHO SWAN instrument data. Due to the poor resolution of the SWAN data, the object was lost until the Catalina Sky Survey observations (or it would have added to SWAN’s discovery total). With a ~5.6-year period, 210P is now making its 4th observed return after past returns in 2003, 2008, and 2014. 249P/LINEAR is also making its 4th observed return after past returns in 2006, 2011, and 2015. It was discovered October 2006 by the LINEAR (Lincoln Laboratory Near-Earth Asteroid Research) project with a 1-m telescope based outside of Socorro, New Mexico.

 

210P was at perihelion on April 12 at 0.53 au. Observations submitted to the COBS site have 210P between magnitude 10.8 and 12.6 during the second half of April. 210P should rapidly fade this month as it moves through Taurus (May 1-2), Auriga (2-11), Gemini (11-23), and Cancer (23-31).

 

In June/July, 249P may become a faint visual object at low elongation. I expected 249P to have become active in April, but CCD observations still suggest the comet is inactive and still a faint 18th magnitude. CCD imagers are requested to routinely monitor 249P to record the start of activity. This month 249P is visible from both hemispheres as it moves through Hydra (May 1-11), Cancer (11-31), and Gemini (31). At some point, activity will start, and its brightness should catch up to the below prediction.

 

210P/Christensen
T = 2020-Apr-12  q = 0.53 au                                     Max El
Jupiter-family comet? / Active Asteroid?                          (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01  12.4   05 01  +27 05   0.682   1.141    36    Tau    16    1
2020-05-06  13.0   05 42  +28 55   0.748   1.122    40    Aur    19    3
2020-05-11  13.7   06 22  +29 57   0.817   1.119    44    Aur    22    6
2020-05-16  14.4   07 02  +30 13   0.888   1.132    48    Gem    24    9
2020-05-21  15.0   07 40  +29 46   0.961   1.159    51    Gem    26   11
2020-05-26  15.6   08 14  +28 45   1.033   1.199    54    Cnc    27   14
2020-05-31  16.2   08 46  +27 19   1.105   1.251    57    Cnc    27   17
2020-06-05  16.8   09 14  +25 38   1.177   1.313    59    Cnc    27   19
  Comet Magnitude Parameters --- H = 16.0, 2.5n = 17.5 (from S. Yoshida)

 

249P/LINEAR

T = 2020-Jun-26  q = 0.50 au                                     Max El
Jupiter-family comet? / Active Asteroid?                          (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01  15.5   09 22  +01 22   1.226   0.529   101    Hya    44   49
2020-05-06  15.1   09 09  +03 44   1.156   0.516    92    Hya    40   46
2020-05-11  14.6   08 57  +06 09   1.083   0.502    84    Hya    36   43
2020-05-16  14.0   08 44  +08 38   1.010   0.488    75    Cnc    30   38
2020-05-21  13.4   08 30  +11 14   0.936   0.473    67    Cnc    24   33
2020-05-26  12.8   08 15  +14 02   0.862   0.457    57    Cnc    18   27
2020-05-31  12.1   07 55  +17 05   0.789   0.443    47    Cnc    11   20
2020-06-05  11.4   07 31  +20 22   0.717   0.432    36    Gem     4   11
  Comet Magnitude Parameters --- H = 15.5, 2.5n = 16.0 (from S. Yoshida)

 

C/2020 H2 (Pruyne) –Theodore Pruyne of the Catalina Sky Survey (Lunar and Planetary Laboratory, University of Arizona) first spotted C/2020 H2 on 2020 April 26 UT with the 0.68-m Catalina Schmidt. It was near perihelion (T = 2020 Apr. 27 at 0.83 au) at discovery.

 

I was able to observe it on Apr. 28.46 with the iTelescope 0.1-m f/5 T20 telescope. It was V = 12.5 with a 4.7' coma. The comet is currently observable from both hemispheres in the morning sky. It is moving rapidly north through Pegasus (May 1-3), Lacerta (3-6), Andromeda (6-9), Cassiopeia (9-13), Cepheus (13-22), Camelopardalis (22-30), and Ursa Major (30-31) and will become a solely northern object over the next few days. Closest approach to Earth occurs on May 7/8 at 0.66 au. The comet is likely near it brightest and should start fading in another week or two as it moves away from the Sun and Earth. 

 

C/2020 H2 (Pruyne)
T = 2020-Apr-27  q = 0.83 au                                     Max El
Long period comet                                                 (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01  12.4   22 41  +26 14   0.836   0.708    55    Peg    30   11
2020-05-06  12.3   22 55  +42 33   0.849   0.661    56    Lac    38    0
2020-05-11  12.4   23 23  +59 35   0.871   0.668    58    Cas    40    0
2020-05-16  12.7   00 36  +73 54   0.902   0.730    59    Cep    37    0
2020-05-21  13.1   04 05  +80 36   0.941   0.831    60    Cep    34    0
2020-05-26  13.6   07 14  +76 49   0.986   0.957    60    Cam    38    0
2020-05-31  14.0   08 18  +71 00   1.037   1.096    58    UMa    40    0
2020-06-05  14.5   08 46  +65 59   1.092   1.242    56    UMa    39    0
            Comet Magnitude Parameters --- H = 13.7, 2.5n = 7.5

 

New Discoveries, Recoveries and Other Comets in the News

 

C/2020 H3 (Wierzchos) - Kacper W. Wierzchos of the Catalina Sky Survey discovered his first comet to bear his name. C/2020 H3 was found on April 25 with the Mount Lemmon 1.5-m reflector. The comet was 19th magnitude at discovery and will peak at 18th magnitude around the time of its 2020 June 5 perihelion at 2.30 au.

 

P/2020 H1 = P/2005 JD108 (Catalina-NEAT) - Erwin Schwab (Egelsbach, Germany) used the European Space Agency's 1.0-m f/4.4 Optical Ground Station on Tenerife to recovery this comet. It was 19th magnitude in images taken on April 26 by D. Abreu. The comet is predicted to peak at 18th magnitude next summer. Perihelion occurs on 2021 December 30 at 4.06 au. P/2020 H1 is on a 16-year orbit and is making its first return since 2005 when it was discovered by both the Catalina Sky Survey and NEAT programs.

 

P/2020 G1 (Pimental) – Eduadro Pimental discovered this 15th magnitude comet with the Southern Observatory for Near Earth Research (SONEAR) 0.28-m f/2.2 astrograph (Celestron RASA 11”) at Oliveira, Brazil on April 13. The comet was at a solar elongation of 50 degrees and small heliocentric distance of 0.77 au at discovery. P/2020 G1 is a periodic comet though its orbital period is still uncertain with a nominal period of ~7 years. Perihelion was on 2020 March 17 at 0.51 au so the comet is currently fading.

 

2020 FP7 – This apparently asteroidal object is on a cometary ~400 +/- 100 year orbit with a perihelion in mid-2024 at ~7 au. FP7 is currently 21st magnitude but will brighten to 18-19th magnitude near perihelion. It was first observed by Pan-STARRS1 on March 21.

 

2020 FE5 – 2020 FE5 is another apparently asteroidal object on a 13 +/- 2 year orbit. It was first observed by the Mount Lemmon Survey on March 24 at 21st magnitude. Perihelion occurs in April 2022 at 4.41 au. Unless the object becomes active it will peak at 21st magnitude.

 

A/2020 F7 – 20th magnitude A/2020 F7 was first seen with the Mount Lemmon Survey’s 1.5-m on March 22. The comet has a ~23,000 year orbital period and comes to perihelion in November 2021 at 5.33 au. Unless the object becomes active it will peak at 19th magnitude.

 

C/2020 F6 (PANSTARRS) – The Pan-STARRS 1 1.8-m telescope on Haleakala, Maui was used to discover this comet on March 21. The comet is currently at its peak brightness of 20th magnitude as it is also near its 2020 April 12 perihelion at 3.51 au.

 

C/2020 F5 (MASTER) – The Mobile Astronomical System of the Telescope-Robots (MASTER) program is an all-sky monitoring program operated by a consortium led by the Lomonosov Moscow State University. A 0.40-m f/2.5 reflector located near San Juan, Argentina spotted this 15th magnitude comet at far southern declinations (-77 deg) on March 28. The comet is a long-period comet with perihelion on 2021 March 22 at 4.34 au. The comet is expected to brighten to 14th magnitude in late 2021.

P/2020 F4 = P/2011 GN5 (PANSTARRS) – The Pan-STARRS 1 telescope found this comet at 20th magnitude on March 24. A large number of pre-discovery observations dating back to 2002 were found. The object was even designated as an asteroid in 2011. Perihelion was on 2019 November 30 at 2.74 au. Thanks to all of the pre-discovery observations, this year marks the comet’s 3rd observed return. It is due back at perihelion in 9 years.

 

C/2020 F2 (ATLAS) – C/2020 F2 (ATLAS) is a very large perihelion object first seen by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) on March 21 with their 0.5-m f/2 telescope on Haleakala. Currently a 19th magnitude object, F2 may get as bright as 16th magnitude around the time of its mid-2022 perihelion at 8.8 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)

[Octans]

C/2020 F3 (NEOWISE) – Another comet flying under the radar is C/2020 F3 (NEOWISE). Discovered by the NEOWISE, or Near-Earth Object Wide-field Infrared Survey Explorer, spacecraft on March 27, C/2020 F3 was a faint 15-16th magnitude object at discovery. It has since rapidly brightened to between magnitude 10.3 (Chris Wyatt, visual, April 25.38) and 10.5 (Carl Hergenrother, CCD, April 28.38).

While it's certainly brightening (and possibly at an above average rate), I don't think it's been quite as fast as these magnitudes might suggest. A lot of the earlier estimates were small aperture photometry capturing only the nuclear condensation and missing the very large, diffuse gas coma the later estimates capture. Michael Mattiazzo had estimated it as "at least 13th magnitude" from a DSLR image shortly after discovery, on April 2: https://groups.io/g/...l/message/28375 That's could still be in line with an n=4 brightening trend allowing for reasonable uncertainties (could also potentially be slightly faster, maybe up to n=5 or even 6 at the upper end, but looks to be well short of C/2019 Y4's brightening rate a couple months ago at least).

Edited by Octans, 02 May 2020 - 04:00 AM.

[Aquarellia]

What a huge work again Carl !

Thank you so much to share all those informations !

Michel

[kdenny2]

Updated predictions for C/2020 F8 (NEOWISE) from astro.vanbuitenen.nl, FYI.

 

http://astro.vanbuit...nl/comet/2020F3

Edited by kdenny2, 02 May 2020 - 01:08 PM.

[Octans]

Updated predictions for C/2020 F8 (NEOWISE) from astro.vanbuitenen.nl, FYI.

 

http://astro.vanbuit...nl/comet/2020F3

That looks like an oversight by an automated fitting routine that's fitting nuclear magnitudes together with total magnitudes. Since the nuclear magnitudes are from early time, they confuse the fitter into thinking the brightening is much, much faster than it is when it's really showing an artifact of fitting two distinctly different sets of data as though they were one.

Edited by Octans, 02 May 2020 - 02:05 PM.

[Vickx]

What a pleasant reading!

We are all looking forward to see C/2020 F8 (SWAN).

Thank you, Carl!

Just please correct the Const column in the 58P table.

[Rich (RLTYS)]

Carl, downloaded the larger PDF report and it was great! Loved all the images!  

[Carl H.]

What a pleasant reading!

We are all looking forward to see C/2020 F8 (SWAN).

Thank you, Carl!

Just please correct the Const column in the 58P table.

Thanks for pointing out the constellation errors in the 58P table. The constellation should be Pisces and not Virgo (copy and paste from 88P that wasn't corrected). Unfortunately, I don't think I can update it in the original post so here's a new ephemerides table.

 

58P/Jackson-Neujmin

T = 2020-May-27  q = 1.38 au                                     Max El
Jupiter-family comet                                              (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2020-05-01  10.9?  00 16  +01 41   1.413   2.088    36    Psc     0   17
2020-05-06  10.7?  00 32  +02 51   1.401   2.066    37    Psc     0   17
2020-05-11  10.6?  00 49  +03 59   1.391   2.046    37    Psc     0   18
2020-05-16  10.5?  01 06  +05 06   1.384   2.029    38    Psc     0   18
2020-05-21  10.5?  01 23  +06 10   1.380   2.015    38    Psc     0   18
2020-05-26  10.5?  01 40  +07 11   1.378   2.003    39    Psc     0   19
2020-05-31  10.5?  01 57  +08 08   1.378   1.993    39    Psc     0   19
2020-06-05  10.5?  02 13  +09 01   1.381   1.985    40    Psc     0   19
            Comet Magnitude Parameters --- H = 5.5, 2.5n = 25.0

[Zorbathegeek]

Well, C/2020 F8 (SWAN) has really stalled over the past 5 days. If anything, I'd say it's a fraction fainter than it was on 1st May. Hopefully, it'll have another outburst. Ray.

[Carl H.]

I was able to catch of glimpse of C/2020 F8 (SWAN) from my backyard in Tucson (32N) with 30x125s. By the time it cleared the roof of my house, the sky was already bright. Still I'd say it was an uncertain magnitude 5.6 with ~4" coma. Undoubtably, I wasn't seeing the entire coma.

 

I agree with Ray that the comet has stalled or even faded after its recent outburst. Even a stall in brightness means the comet is intrinsically fading after accounting for the change in heliocentric and geocentric distance. That's not unexpected after an outburst. We'll just have to wait and see when/if it starts brightening again.

[Zorbathegeek]

I was quite surprised and delighted to find C/2019 U6 (LEMMON) tonight from my Bortle 7 zone with a full moon at 15 degrees altitude, using my 10" dobsonian. With both of those limiting factors I would estimate that the comet is about 8.5 magnitude. So nice to have another bright comet appear just as C/2020 F8 (SWAN) slips below my horizon. Ray.

[Carl H.]

Ray, I was just looking at some of the recent C/2019 U6 magnitude estimates from COBS. The comet continues to brighten at a consistent and rapid rate and may now be as bright as 7.9. 

 

At some point the rate of brightening will decrease. If it were to revert to a n=3 rate right now, it would still peak around magnitude 6.0. Not bad for a comet that will be better placed for a longer period of time than Y4, F3, or F8.

[Anduin]

C/2019 U6 Lemmon from a Bortle 9 sky and full moon.




Enviado do meu iPhone usando Tapatalk

[Cirus]

Ray, I was just looking at some of the recent C/2019 U6 magnitude estimates from COBS. The comet continues to brighten at a consistent and rapid rate and may now be as bright as 7.9. 

 

At some point the rate of brightening will decrease. If it were to revert to a n=3 rate right now, it would still peak around magnitude 6.0. Not bad for a comet that will be better placed for a longer period of time than Y4, F3, or F8.

 

I was thinking what if it did the opposite and had an outburst close to perihelion? Could it become a bright comet with a visual magnitude greater than 0?

 

For southern hemisphere viewers, this comet sits at an amazing position. It hangs around 30-40 degrees above the horizon after full darkness. When it hits it's brightest near perihelion it'll be during a new moon during the early evening. Everything about this comet is super convenient.

Edited by Cirus, 09 May 2020 - 10:41 PM.

[Carl H.]

I was thinking what if it did the opposite and had an outburst close to perihelion? Could it become a bright comet with a visual magnitude greater than 0?

 

For southern hemisphere viewers, this comet sits at an amazing position. It hangs around 30-40 degrees above the horizon after full darkness. When it hits it's brightest near perihelion it'll be during a new moon during the early evening. Everything about this comet is super convenient.

C/2019 U6 hasn't shown any evidence of outbursts, though anything is possible. It would need a ~5-6 magnitude outburst to get to 0th magnitude. Outbursts of that size are very rare but they do happen.

[Carl H.]

After a few nights of clouds, some thunder, and a few sprinkles (at least here at the house), I was able to see 4 comets last night with the 30x125s.

 

Evening comets

C/2017 T2 (PANSTARRS) was seen at magnitude 8.5 with a condensed (DC = 5) 3' coma.

C/2019 Y1 (ATLAS) was at 9.2 with a diffuse (DC = 3) 3' coma.

C/2019 Y4 (ATLAS) was still visible at magnitude 8.8. The coma was very diffuse (DC = 1) and elongated (3x7' coma). Y4's visual appearance hasn't changes much over the past few weeks.

 

Morning comet

C/2020 F8 (SWAN) was seen in the morning. It was an easy object in 30x125s at mag 5.7 with a very condensed (DC = 6) 3' coma and a hint of a tail. The comet was difficult but could be seen with averted vision in 10x50s.

 

SWAN is at its closest approach to Earth (0.56 au) and only two weeks from perihelion. Unless it experiences another outburst soon, it is likely that the comet already peaked in brightness back around May 2.

[Carl H.]

This image by Stephen O'Meara does a good job of showing what SWAN looked like on the morning of May 12 in 30x125 binoculars though the color and brightness was less intense in the binoculars.

[Carl H.]

Some updates:

 

Here are current lightcurves for the 3 of the brighter inbound comets: C/2019 U6 (Lemmon) in black, C/2020 F3 (NEOWISE) in blue, and C/2020 F8 (SWAN) in red. Plotted are visual magnitude estimates made by a subset of observers reporting to the COBS site. The curves were produced in Seiichi Yoshida's Comets for Windows program.

 

 

C/2020 F8 (SWAN)'s recent outburst appears to be over and the comet has settled back down to around magnitude 5.5-6.0. It is interesting that it has fallen back to its pre-outburst brightening trend. Perhaps that is its nominal state. If so, it's rather pathetic with a 2.5n = 1.6. Remember, that 2.5n = 5.0 means steady state dust and gas production. 2.5n = 1.6 means SWAN's production is actually decreasing with time. It is the comet's decreasing distance to the Sun and Earth that is offsetting the intrinsic fading and causing the comet to increase in apparent magnitude (the brightness we see). Chances are SWAN will not get much brighter than it is now unless it has another outburst. We can hope...

 

I was able to observe SWAN on the mornings of May 5, 12, 13, and 14. I'll have to admit that I slept right through my alarm the past two nights. On the 12th, 13th, and 14th, I placed SWAN at magnitude 5.6 to 5.7 with a hint of a tail in 30x125 binoculars.

 

C/2020 F3 (NEOWISE) rapidly brightened till late April. It has now settled down to a brightening rate of 2.5n ~ 9 with recent visual observations placing it around 9th magnitude. That rate would result in a peak brightness of around 2nd-3rd magnitude at perihelion. Before we get too excited, this comet is intrinsically faint and not much of a dust producer. It is highly likely its brightening trend will slow down even further and a complete disintegration cannot be ruled out.

 

The comet will still be observable from the southern hemisphere through early June. We'll next see it in the SOHO LASCO C3 field-of-view in late June. If NEOWISE is still with us, the comet will be visible from the northern hemisphere only days after its July 3 perihelion, and from the southern hemisphere in late July.

 

C/2019 U6 (Lemmon) is now up to 8th magnitude. Its rapid rise in brightness also appears to have ceased. If it brightens at a 2.5n = 7.5 rate which appears to be close to its brightening rate over the last two weeks, it may peak at around magnitude 6.0.

 

Last night was the first time that I could not be certain of detecting C/2019 Y1 (ATLAS) and C/2019 Y4 (ATLAS) in my 30x125s. I suspected both comets, but could not be sure. 

 

C/2017 T2 (PANSTARRS) continues to hold steady around magnitude 8.5. I placed it at 8.6 last night.

 

249P/LINEAR is a low activity comet that may have originated in the Main Belt rather than the Kuiper Belt like most Jupiter family comets. 249P is expected to peak at 10th magnitude around its June 26 perihelion at 0.50 au. I was expecting the comet to have already become active by now but observations with the iTelescope T30 on May 16 showed the comet to still be around magnitude 18.5. There was a hint of a 1' tail so activity may have commenced even if a detectable coma has yet to form. 

[Zorbathegeek]

I got another look at C/2019 U6 (LEMMON) tonight, without the adverse influence of a full moon. The comet  now appears reasonably condensed and I would estimate it is currently 7.5 magnitude. Ray. 

[Carl H.]

My latest visual observations of C/2020 F8 (SWAN) from Tucson. The comet appears fainter then it was a week ago. 

 

May 18.46, 5.9, 4' (Carl Hergenrother, Tucson, AZ, U.S.A., 30x125 binoculars);

May 17.46, 5.8, 4' (Carl Hergenrother, Tucson, AZ, U.S.A., 30x125 binoculars);

 

I think I'll get one more morning before the comet moves behind the mountains to the north of my home. Perhaps I'll pick it up when it moves into the evening sky though it will be competing with a brightening moon-lit sky.

[Zorbathegeek]

I observed C/2019 U6 (LEMMON) again this evening. I can't detect any change from a couple of nights ago and would still put this comet at 7.5 magnitude. I also tried to find C/2020 F3 (NEOWISE) as it was an easy star hop from Saiph in Orion. I think I could detect something but am not 100% sure. 9.00 magnitude is about my limit for comets when I'm observing from home. Ray.

[Carl H.]

I think I have made my final observations of C/2020 F8 in the morning sky. From my house, there is a mountain range to the north and as the comet moved north it moved into a par of the horizon with increasing obstruction from the mountains. We'll see if I can pick it up again in the evening.

 

May 20.47, 6.2, 5' (Carl Hergenrother, Tucson, AZ, U.S.A., 30x125 binoculars);

May 19.46, 6.0, 5' (Carl Hergenrother, Tucson, AZ, U.S.A., 30x125 binoculars);

 

The comet has faded over the past week. It was a relatively easy object a week ago. My last few observations showed a much fainter object with less condensation. Based on some recent CCD images posted over at comets-ml, the comet may, emphasis on may, be breaking up. Time will tell.

[Zorbathegeek]

I've been fretting under cloudy skies for what feels like eternity, hoping to see C/2020 F3 (NEOWISE) before it becomes a horizon hugger and too low for me (although it will get higher again in August from my SH location) and am happy to say that I finally located it from my urban location. I would place it around 8.5 magnitude, although a couple of recent observations have it brighter than this. 

 

I also observed C/2019 U6 (LEMMON) again. The comet is now around 7.0 magnitude and it was well positioned with its coma in front of a 9th magnitude star, and its stellar like core very close to said star.  

Edited by Zorbathegeek, 26 May 2020 - 05:10 AM.

[Carl H.]

Oh well, it appears that there is no doubt that C/2020 F8 (SWAN) has fallen apart. Check out this recent image posted on comets-ml by Danilo Pivato.

 

I have yet to see the comet in the evening sky, but reports to the COBS site place it somewhere between magnitude 6.8 and 8.4. I'll try again this evening as the comet should be clear of the mountains here while the sky is reasonably dark, but I'm not confident it is bright enough to be seen from my locale.