[Iaude] CBET 4896: COMET C/2020 X2
quai at eps.harvard.edu
quai at eps.harvard.edu
Mon Dec 14 02:23:18 EST 2020
Electronic Telegram No. 4896
Central Bureau for Astronomical Telegrams
Mailing address: Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network
COMET C/2020 X2 (ATLAS)
A comet discovery was reported to the Minor Planet Center on Dec. 10 by
the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program
(discovery observations tabulated below) from CCD images taken on Dec. 10.5
UT with a 0.5-m f/2 Schmidt reflector at Mauna Loa, Hawaii (with no details
given about appearance); a day later, A. Heinze told the MPC that the comet
showed a condensed 4".5 coma.
2020 UT R.A. (2000) Decl. Mag.
Dec. 10.50409 6 58 30.87 +19 19 55.0 18.2
10.50701 6 58 30.85 +19 19 55.7 18.7
10.54240 6 58 30.02 +19 20 05.2 18.7
10.54516 6 58 29.87 +19 20 05.5 18.9
After the comet was posted on the MPC's PCCP webpage, other CCD astrometrists
have also commented on the cometary appearance. Four stacked 60-s CCD
exposures taken remotely on Dec. 12.35 UT by H. Sato, Tokyo, Japan, with a
0.43-m f/6.8 astrograph located near Mayhill, NM, USA, show a strongly
condensed and elongated coma of size 6" x 12" with no tail; the magnitude was
18.4 as measured within a circular aperture of radius 7".6. A. Valvasori,
Padulle, Italy, writes that fifteen stacked unfiltered 120-s exposures taken
remotely by E. Guido and himself on Dec. 13.2 with an iTelescope 0.32-m f/7.9
reflector at Nerpio, Spain, show a diffuse coma about 7".5 in diameter and of
magnitude 18.9-19.1.
Four nights of apparently asteroidal pre-discovery observations of this
comet, from three different observatories and spanning 2020 Oct. 14-Dec. 8,
were identified by the Minor Planet Center in its "isolated tracklet file"
(with Mt. Lemmon Survey observations on Oct. 14.4 UT giving mag 19.1-19.7);
in addition, pre-discovery Mt. Lemmon Survey observations reported after the
ATLAS discovery was reported date to Sept. 25.5 (mag 19.7-19.9), Oct. 29.4
(mag 19.0-19.3), and Nov. 23.5 (mag 18.6-18.8). The available astrometry
appear on MPEC 2020-X156.
The following elliptical orbital elements by S. Nakano (CBAT) are from
50 observations spanning Sept. 25-Dec. 13 (mean residual 0".4). These
elements indicate that the comet passed 1.19 AU from Jupiter in 1955 Oct. and
2.54 AU from Neptune in 1985 June, and that the comet will pass 2.99 AU from
Saturn in 2083 Nov.
Epoch = 2020 Nov. 7.0 TT
T = 2020 Nov. 16.11268 TT Peri. = 347.39646
e = 0.7659816 Node = 105.45808 2000.0
q = 3.8283698 AU Incl. = 18.19220
a = 16.3592685 AU n = 0.01489561 P = 66.17 years
Epoch = 2087 Nov. 16.0 TT
T = 2087 Nov. 8.39301 TT Peri. = 347.72636
e = 0.7676293 Node = 105.14563 2000.0
q = 3.8449245 AU Incl. = 18.10448
a = 16.5465107 AU n = 0.01464348 P = 67.31 years
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 11.5 and 2.5n = 8 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2020 11 27 07 02.34 +18 25.7 3.021 3.829 139.9 9.5 18.6
2020 12 02 07 01.24 +18 44.5 2.979 3.830 145.3 8.4 18.5
2020 12 07 06 59.76 +19 04.9 2.942 3.832 150.7 7.2 18.5
2020 12 12 06 57.94 +19 26.5 2.912 3.834 156.2 5.9 18.5
2020 12 17 06 55.83 +19 49.3 2.888 3.836 161.8 4.6 18.5
2020 12 22 06 53.48 +20 13.1 2.872 3.838 167.5 3.2 18.5
2020 12 27 06 50.97 +20 37.5 2.863 3.841 173.1 1.8 18.5
2021 01 01 06 48.38 +21 02.3 2.862 3.845 177.9 0.5 18.5
2021 01 06 06 45.76 +21 27.2 2.868 3.848 174.8 1.3 18.5
2021 01 11 06 43.20 +21 52.0 2.882 3.852 169.3 2.7 18.5
2021 01 16 06 40.78 +22 16.3 2.903 3.857 163.6 4.1 18.5
2021 01 21 06 38.56 +22 40.1 2.932 3.862 158.0 5.5 18.5
2021 01 26 06 36.62 +23 03.2 2.967 3.867 152.5 6.8 18.6
2021 01 31 06 35.00 +23 25.3 3.009 3.873 147.0 8.0 18.6
2021 02 05 06 33.76 +23 46.5 3.057 3.878 141.6 9.1 18.6
2021 02 10 06 32.92 +24 06.5 3.111 3.885 136.3 10.1 18.7
2021 02 15 06 32.51 +24 25.4 3.170 3.892 131.2 11.0 18.7
2021 02 20 06 32.56 +24 43.2 3.233 3.899 126.1 11.8 18.8
2021 02 25 06 33.07 +24 59.7 3.301 3.906 121.2 12.5 18.8
2021 03 02 06 34.03 +25 15.1 3.372 3.914 116.3 13.1 18.9
2021 03 07 06 35.44 +25 29.3 3.446 3.922 111.6 13.6 18.9
2021 03 12 06 37.29 +25 42.3 3.523 3.930 107.0 14.0 19.0
2021 03 17 06 39.57 +25 54.1 3.601 3.939 102.6 14.3 19.0
2021 03 22 06 42.25 +26 04.8 3.681 3.948 98.2 14.5 19.1
2021 03 27 06 45.32 +26 14.2 3.763 3.958 93.9 14.6 19.2
2021 04 01 06 48.74 +26 22.4 3.844 3.968 89.7 14.6 19.2
2021 04 06 06 52.50 +26 29.4 3.927 3.978 85.6 14.5 19.3
2021 04 11 06 56.57 +26 35.2 4.009 3.988 81.6 14.4 19.3
2021 04 16 07 00.94 +26 39.8 4.091 3.999 77.7 14.2 19.4
2021 04 21 07 05.57 +26 43.1 4.172 4.010 73.9 13.9 19.4
2021 04 26 07 10.45 +26 45.2 4.251 4.021 70.1 13.6 19.5
2021 05 01 07 15.55 +26 46.1 4.330 4.033 66.4 13.2 19.5
2021 05 06 07 20.85 +26 45.8 4.407 4.045 62.7 12.8 19.6
2021 05 11 07 26.33 +26 44.3 4.482 4.058 59.1 12.3 19.6
2021 05 16 07 31.98 +26 41.5 4.556 4.070 55.6 11.8 19.7
2021 05 21 07 37.77 +26 37.6 4.626 4.083 52.1 11.3 19.7
2021 05 26 07 43.68 +26 32.5 4.695 4.097 48.6 10.7 19.8
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2020 CBAT
2020 December 14 (CBET 4896) Daniel W. E. Green
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