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)
