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ALPO Comet News for December 2019

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#1 Carl H.

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Posted 03 December 2019 - 10:23 AM

ALPO COMET NEWS FOR DECEMBER 2019

 

By Carl Hergenrother - 2019-December-3
 


 

The monthly ALPO Comet News PDF can be found on the ALPO Comet Section website (http://www.alpo-astr....org/cometblog/). The PDF version also includes many more magnitude estimates, sketches and images.

 

C/2017 T2 (PANSTARRS) is well placed in the evening sky for northern observers and should become brighter than 10th magnitude this month. CCD imagers are encouraged to image a number of fainter comets this month. In particular, the following three are of interest. Interstellar visitor 2I/Borisov will be at its best around 15th magnitude. December and January will see short-period comet 289P/Blanpain pass within 0.09 au of the Earth. How bright this comet gets is uncertain as it is a faint, outburst prone object. Speaking of outburst prone comets, the British Astronomical Society invites CCD photometrists to join their effort to monitor the outbursts of 29P/Schwassmann-Wachmann.

 

Bright Comets (magnitude < 10.0)


 

C/2017 T2 (PANSTARRS) – C/2017 T2 (PANSTARRS) has finally arrived as an object visually observable in modest size telescopes. As a result, we’ve received images, sketches and magnitude estimates from multiple observers (Michel Deconinck, J. J. Gonzalez, Carl Hergenrother, John Maikner, Michael Rosolina and Chris Wyatt). Over the last week of November, ALPO contributors found the comet to be between magnitude 10.2 and 11.1. Many commented on the compactness of the coma (1-3’) and its narrow tail (up to 10’ in length). An interesting non-feature has been the comet’s lack of an outer gas coma, the sort that give similarly bright comets their blue-green color in CCD images. I’ve only seen one image online that shows this feature (a nearly 1-hour exposure by Michael Jager with a Celestron RASA 8” that can be seen at https://spaceweather..._1575315837.jpg). If this outer coma continues to develop, we may see a marked increase in the comet’s reported brightness.

 

This December, C/2017 T2 (PANSTARRS) continues its march inwards towards a 2020 May 4 perihelion at 1.62 au. C/2017 T2 should start December around magnitude 10 and brighten to 9.5 by December 1 as it moves through Auriga (Dec 1-3), Perseus (3-20), Camelopardalis (20-30) and Perseus again (30-31). It is well placed in the evening sky for northern observers. Unfortunately, the comet will be located very low or below the horizon for southern hemisphere observers.

 

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

2019-12-01  10.2   04 56  +46 19   2.576   1.650   154    Aur    84    4
2019-12-06   9.9   04 44  +48 10   2.529   1.606   154    Per    82    2
2019-12-11   9.8   04 30  +49 55   2.484   1.571   151    Per    80    0
2019-12-16   9.8   04 16  +51 31   2.438   1.546   148    Per    78    0
2019-12-21   9.7   04 00  +52 54   2.393   1.529   143    Cam    77    0
2019-12-26   9.6   03 44  +54 05   2.349   1.521   138    Cam    76    0
2019-12-31   9.5   03 28  +55 02   2.305   1.521   132    Per    75    0
2020-01-05   9.5   03 13  +55 47   2.261   1.527   127    Per    74    0

 

Faint Comets (between magnitude 10.0 and 13.0)

 

29P/Schwassmann-Wachmann – 29P/Schwassmann-Wachmann was discovered photographically in 1927 by German astronomer Arnold Schwassmann and Arno Arthur Wachmann. The duo discovered 4 comets together, three short-period comets (29P, 31P and 73P) and a long-period comet shared with Leslie Peltier (C/1930 D1). Chris Wyatt observed 29P twice in November between magnitude 14.3 on November 2.6 and 14.7 on November 19.4 UT.

 

Comet 29P has experienced a number of small (<1 to 4 magnitude) outbursts this year. Richard Miles at the British Astronomical Society (BAA) is leading an effort to continually monitor 29P and its outbursts. He’s looking for observers to contribute CCD photometry with the following:

 

“a fairly large telescope, say at least 15-cm aperture (the larger the better!) and a focal length of >100 cm, as well as an image scale for your camera of preferably <2.0 “/pixel. Use a monochrome camera, and take a series of exposures using either no filter, a Luminance filter, or a red filter. I like to use an exposure time of 60 sec but if your mount does not track well then shorten the duration to say 20 or 30 sec as the objective is to stack the images to create a higher quality stacked frame for measuring.”

 

You can find more information at the BAA’s “Observing the outbursting comet 29P/Schwassmann-Wachmann” page ( https://britastro.org/node/18562 ).

 

29P/Schwassmann-Wachmann

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

2019-12-01  12-14  00 25  +13 11   5.780   5.193   122    Psc    63   34
2019-12-06  12-14  00 24  +13 04   5.781   5.263   117    Psc    63   31
2019-12-11  12-14  00 25  +12 58   5.782   5.336   112    Psc    63   29
2019-12-16  12-14  00 25  +12 53   5.782   5.412   107    Psc    63   26
2019-12-21  12-14  00 26  +12 51   5.783   5.490   102    Psc    63   23
2019-12-26  12-14  00 27  +12 50   5.783   5.570    97    Psc    63   20
2019-12-31  12-14  00 28  +12 51   5.784   5.650    92    Psc    62   17
2020-01-05  12-14  00 30  +12 54   5.784   5.731    88    Psc    61   14

 

C/2018 N2 (ASASSN) - Comet C/2018 N2 (ASASSN) was discovered 16 months ago on 2018 July 7 by the All-Sky Automated Survey for Supernovae (ASAS-SN) program. Since discovery, ASASSN has brightened slowly. ASASSN is now passed its November 11 perihelion (q = 3.12 au). The section received a sketch of this comet from Michel Deconinck as well as 2 magnitude estimates from J. J. Gonzalez (11.2 with a 2’ coma on the 18th) and Chris Wyatt (12.4 with a 1’ coma on the 19th). Submissions to the COBS site during the last week of November placed C/2018 N2 between magnitude 11.4 and 12.1. This month, C/2018 N2 is well placed for northern observers at a +39 degree declination in Andromeda. With the comet on the wrong side of perihelion and closest approach to Earth, it should slowly fade from magnitude ~11.8 to ~12.2.

 

C/2018 N2 (ASASSN)

T = 2019-Nov-11  q = 3.12 au                                     Max El
Long-Period comet - dynamically old                               (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2019-12-01  11.8   23 48  +39 09   3.131   2.528   119    And    89    6
2019-12-06  11.8   23 43  +39 10   3.134   2.595   114    And    89    4
2019-12-11  11.9   23 38  +39 12   3.138   2.666   109    And    89    1
2019-12-16  12.0   23 35  +39 15   3.143   2.738   105    And    88    0
2019-12-21  12.1   23 32  +39 21   3.149   2.812   100    And    83    0
2019-12-26  12.1   23 30  +39 29   3.155   2.887    96    And    79    0
2019-12-31  12.2   23 29  +39 40   3.162   2.963    92    And    74    0
2020-01-05  12.3   23 29  +39 55   3.170   3.038    88    And    70    0

 

Fainter Comets of Interest (probably fainter than magnitude 13.0)


 

2I/2019 Q4 (Borisov) – The first bona fide interstellar comet, 2I/2019 Q4 (Borisov), was discovered by Gennady Borisov on August 30 with a 0.65-m f/1.5 astrograph of his own making at MARGO observatory near Nauchnij, Crimea. Pre-discovery observations from the Zwicky Transient Facility on Mount Palomar have been found as far back as 2018 October 31 when the comet was located at 8.55 au from the Sun.

 

The comet comes to perihelion this month on December 8 at 2.01 au. Based on its brightness through early November, it should peak at around magnitude 15.1. There were few magnitude estimates submitted to the COBS and ALPO last month. Submissions to the Minor Planet Center have been running faint (16-17th magnitude) but this is also common for astrometric observations. As a result of this uncertainty, its actual brightness is a bit in question. The comet is visible from both hemispheres in the morning sky as it moves through Crater (Dec 1-17) and Hydra (17-31) though it will become progressively more difficult to observe from the northern hemisphere. On the other hand, it becomes better placed for folks in the southern hemisphere.

 

2I/2019 Q4 (Borisov)
T = 2019-Dec-08  q = 2.01 au                                     Max El
Interstellar comet                                                (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2019-12-01  15.2   11 15  -12 33   2.014   2.048    73    Crt    34   29
2019-12-06  15.1   11 24  -16 21   2.007   2.010    75    Crt    32   33
2019-12-11  15.1   11 32  -20 12   2.007   1.980    77    Crt    29   37
2019-12-16  15.1   11 40  -24 03   2.013   1.958    78    Crt    25   42
2019-12-21  15.1   11 48  -27 53   2.026   1.944    80    Hya    22   46
2019-12-26  15.1   11 56  -31 40   2.044   1.937    81    Hya    18   51
2019-12-31  15.2   12 04  -35 21   2.068   1.938    83    Hya    14   55
2020-01-05  15.2   12 11  -38 54   2.097   1.945    84    Cen    11   60

 

289P/Blanpain – 289P/Blanpain will approach to within 0.09 au of Earth on 2020 January 11. It is not expected to get bright due to its usual low activity though it has experienced a number of outbursts in the past. Jean-Jacques Blanpain discovered 289P at 6th magnitude in November 1819. Likely experiencing an outburst at the time of discovery, it went unobserved for the next 194 years until re-discovered by the Catalina Sky Survey in November 2003 as near-Earth asteroid 2003 WY25. Observations in 2005 found it to still be an active comet, albeit at a very low level of activity. In July 2013 while far from perihelion (3.9 au vs perihelion at ~1.0 au), Blanpain experienced a major ~9 magnitude outburst that caused it to brighten from 26th to 17th magnitude. The Phoencids meteor shower is associated with this object. Similar to its parent comet, this shower usually shows little activity except for two outbursts in 1956 and 2014.

 

A number of observations were submitted to the Minor Planet Center in November. The brightest placed the comet at magnitude 17.7 on the 20th (MPC code I47 - Pierre Auger Observatory, Malargue). This is ~3 magnitudes brighter than predicted for a bare inactive nucleus.

 

This month, the comet reaches perihelion on December 20 at 0.96 au. Its geocentric distance falls from 0.28 au on the 1st to 0.11 au on New Year’s. The comet becomes a progressively easier object to observe from the northern hemisphere and more difficult to observe from the southern hemisphere as it moves through Aquarius (Dec 1-18), Pisces (18-26) and Pegasus (26-31) in the evening sky. The predicted magnitudes below are for the inactive nucleus and provide a faint limit. If the comet continues its recent brightening it may be 3+ magnitudes brighter than this prediction.

 

289P/Blanpain
T = 2019-Dec-20  q = 0.96 au                                     Max El
Short-period comet – 5.3-yr orbital period                        (deg)
    Date     Mag    R.A.   Decl.     r       d    Elong  Const  40N  40S

2019-12-01  20.5   22 30  -15 57   1.002   0.275    85    Aqr    34   42
2019-12-06  20.4   22 35  -13 19   0.983   0.250    82    Aqr    36   36
2019-12-11  20.2   22 41  -10 04   0.970   0.223    79    Aqr    39   30
2019-12-16  20.1   22 47  -05 57   0.962   0.196    77    Aqr    42   24
2019-12-21  19.9   22 56  -00 34   0.959   0.169    76    Psc    46   18
2019-12-26  19.6   23 06  +06 45   0.962   0.142    77    Psc    52   10
2019-12-31  19.1   23 21  +17 03   0.970   0.119    80    Peg    60    2
2020-01-05  18.5   23 44  +31 32   0.983   0.101    87    Peg    70    0

 

New Discoveries, Recoveries and Other Comets in the News

 

P/2019 S5 = P/2009 SK280 (Spacewatch-Hill) – Scott S. Sheppard (Carnegie Institution for Science, Washington, DC) reported his discovery of a 21st magnitude comet from images taken on  September 24 with the Blanco 4-m reflector at Cerro Tololo in Chile. Sheppard’s object was identified as a recovery of periodic comet P/2009 SK280 (Spacewatch-Hill). The Minor Planet Center also identified further observation made this year by the Mt. Lemmon Survey 1.5-m reflector on October 3 and 31 and the Pan-STARRS1 1.8-m on October 5. P/Spacewatch-Hill was discovered in September/October 2009 by ALPO Solar Section Coordinator Rik Hill who was using the Mount Lemmon 1.5-m and the Pan-STARRS survey. This time around it reached perihelion on 2019 October 23. Its 10.4-year period orbit lies just inside the orbit of Jupiter and ranges between 4.21 au and 5.35 au from the Sun. It is unlikely to become brighter than ~20th magnitude.

 

C/2019 V1 (Borisov) – Gennedy Borisov (MARGO observatory, Nauchnij, Crimea) used his home-made 0.65-m f/1.5 astrograph to discover his 9th comet overall and 3rd of the year. This is also his 1st discovery since finding interstellar 2I/Borisov. The latest Comet Borisov was found at 19th magnitude on November 1. It is a long-period comet and reaches perihelion on 2020 July 15 at 3.11 au. The comet comes to opposition this month which also corresponds with its peak brightness (18th magnitude).

 

P/2019 V2 (Groeller) – Hannes Groeller used the Mount Lemmon 1.5-m telescope north of Tucson, Arizona to discover this comet on November 3 at 20th magnitude. Perihelion occurs on 2020 November 8 at 4.99 au. P/2019 V2 is a short period comet with an orbital period of 20.3 years. Its orbit is interesting in that perihelion is located near the orbit of Jupiter while its aphelion is located near the orbit of Saturn. It should peak at 19th magnitude during its next two oppositions in 2020 February and 2021 March.

 

In addition to the above discoveries and recoveries, the following objects are designated as asteroids but have comet-like orbits. This doesn’t mean these objects are cometary in origin, but it makes them a good group to watch. My search criteria are based on the JPL Small-Body Database of orbits and is limited to: 1) asteroidal objects with aphelia greater than 4.7 au, but not Hilda (3.85 < a < 4.05 au) or Jupiter Trojan (5.03 < a < 5.43 au) objects and 2) possess a condition code (to filter out uncertain, short arc orbits).

 

Object      Disc.    Peri.   Period    H   Max Brightness Discoverer
            Date     Dist.   (years)
2019 VR1    Nov 04   0.98      4.84  27.0  18-in-Nov2019  MountLemmon
2019 VG2    Nov 02   0.46      4.62  19.9  21-in-Sep2019  PanSTARRS
2019 WF1    Nov 17   1.12      6.56  19.8  20-in-Nov2019  PanSTARRS
2019 WH1    Nov 18   1.05      5.57  21.4  21-in-Dec2019  WISE
2019 WV2    Nov 26   3.28     16.6   15.5  20-in-Dec2019  PanSTARRS

 

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 >.

- Carl Hergenrother (ALPO Comet Section Coordinator)


  • eros312, Aquarellia, zakry3323 and 2 others like this

#2 Carl H.

Carl H.

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Posted Yesterday, 09:52 PM

Nice view of a compact C/2017 T2 in my 30x125 binoculars this evening. The open cluster NGC 1528 was only ~1/3 deg away making for a scenic backdrop.

 

Dec. 16.11, 9.8, 2' (C. W. Hergenrother, Tucson, Arizona, 30x125 binoculars)


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#3 Zorbathegeek

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Posted Today, 12:58 AM

How does it compare with C/2018 W2 when that one was at 10 magnitude? Is it less diffuse and easier to pick up in the large binoculars? Thanks.




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