[Iaude] CBET 4968: COMET C/2021 K1 (ATLAS)
quai at eps.harvard.edu
quai at eps.harvard.edu
Fri May 28 00:14:52 EDT 2021
Electronic Telegram No. 4968
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/2021 K1 (ATLAS)
Peter Veres, Minor Planet Center, found that images of an object that
were obtained on May 14 and 24 with 0.5-m f/2 Schmidt reflectors at Mauna Loa,
Hawaii, and at Haleakala, Hawaii, respectively, in the course of the "Asteroid
Terrestrial-Impact Last Alert System" (ATLAS) search program show cometary
appearance. The ATLAS team had submitted the observations without comment or
flagging, and they went into the MPC's "isolated tracklet file" (ITF) with
separate designations. Veres was using software to search for potential
interesting objects based upon brightness and motion, and he noticed the May
24 observations first, from whence he sought additional identifications and
found linkages to the May 14 ATLAS observations and also to May 22 Pan-STARRS1
ITF astrometry. Veres has access to the actual ATLAS images. The ATLAS
observations are tabulated below. L. Denneau of the ATLAS team subsequently
notes a condensed 6" coma and a straight tail about 10" long extending to the
west (p.a. 265-275 deg) on both nights.
2021 UT R.A. (2000) Decl. Mag.
May 14.59378 23 24 49.83 - 5 53 35.1 16.5
14.59793 23 24 50.24 - 5 53 33.8 16.5
14.60809 23 24 51.31 - 5 53 30.7 17.2
14.62053 23 24 52.59 - 5 53 27.3 17.2
24.60613 23 41 41.47 - 5 06 54.3 16.3
24.61025 23 41 41.85 - 5 06 53.2 16.3
24.61942 23 41 42.76 - 5 06 51.0 16.2
As with the ATLAS observations, this object was reported without comment or
flagging initially in regular survey observations obtained with the
Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on May 22.6 UT (mag
17.6-18.0), submitted as two separate objects on the same night. After the
comet was posted on the MPC's PCCP webpage, R. Weryk (Department of Physics
and Astronomy, University of Western Ontario) noted that the 45-s w-band
Pan-STARRS1 survey images taken on May 22 show a broad tail extending > 50"
towards p.a. 250 degrees; the comet's diffuse head showed a size of about
2".7 (full-width-at-half-maximum) in 1".6 seeing. Weryk also has identified
many pre-discovery Pan-STARRS1 and Pan-STARRS2 observations of this comet
back to 2020 April, when the comet was fainter and it was not possible to
determine any cometary appearance; following are selected dates and
magnitudes: 2020 Apr. 20.6, 21.2-22.8; May 2.55, 22.1; June 15.4, 21.4-22.3;
22.4, 21.1-21.9; July 20.3, 21.7-21.9; Aug. 12.3, 21.3-22.4.
A. Hale, Cloudcroft, NM, USA, finds a relatively condensed coma 9" in
diameter with V magnitude 17.2-17.3 in three 240-s exposures taken in bright
moonlight on May 26.4 with a 0.4-m f/10 Schmidt-Cassegrain telescope of the
Las Cumbres Observatory at Cerro Tololo; there was a straight, somewhat broad
tail 16" long in approximate p.a. 285 degrees. E. Guido, Castellammare di
Stabia, Italy, writes that forty-four stacked 60-s unfiltered exposures taken
remotely by a large group of observers with a "Telescope Live" 0.61-m f/6.5
astrograph located at El Sauce, Chile, on May 27.4 show a compact coma about
20" in diameter of mag 16.8-17.0 with a tail 30" long in p.a. 245 deg.
The available astrometry appears on MPEC 2021-K89. The following
orbital elements by S. Nakano (CBAT) are from 63 observations spanning
2020 Apr. 20-2021 May 26 (mean residual 0".2); they indicate that the comet
passed 2.04 AU from Uranus in 1965 March and 2.55 AU from Jupiter on 2021
Mar. 22 UT.
Epoch = 2021 Apr. 16.0 TT
T = 2021 May 4.66515 TT Peri. = 184.33248
e = 0.8043530 Node = 140.90560 2000.0
q = 2.4979656 AU Incl. = 16.27563
a = 12.7677189 AU n = 0.02160400 P = 45.62 years
Epoch = 2065 Aug. 23.0 TT
T = 2065 Aug. 18.58421 TT Peri. = 184.07244
e = 0.8021749 Node = 140.73611 2000.0
q = 2.4880805 AU Incl. = 16.27506
a = 12.5771713 AU n = 0.02209681 P = 44.60 years
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 10.0 and 2.5n = 10 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2021 05 26 23 43.97 -05 01.0 2.658 2.507 70.4 22.4 16.1
2021 05 31 23 52.04 -04 41.5 2.609 2.511 73.2 22.7 16.1
2021 06 05 23 59.89 -04 24.5 2.560 2.517 76.1 23.0 16.0
2021 06 10 00 07.49 -04 10.2 2.511 2.523 79.0 23.3 16.0
2021 06 15 00 14.83 -03 58.9 2.462 2.530 82.1 23.4 16.0
2021 06 20 00 21.88 -03 50.7 2.414 2.538 85.1 23.5 16.0
2021 06 25 00 28.63 -03 46.0 2.366 2.548 88.3 23.5 15.9
2021 06 30 00 35.04 -03 44.8 2.319 2.558 91.6 23.4 15.9
2021 07 05 00 41.10 -03 47.4 2.273 2.568 94.9 23.2 15.9
2021 07 10 00 46.76 -03 53.9 2.228 2.580 98.4 22.9 15.9
2021 07 15 00 52.01 -04 04.5 2.184 2.593 101.9 22.6 15.8
2021 07 20 00 56.82 -04 19.2 2.141 2.606 105.6 22.1 15.8
2021 07 25 01 01.15 -04 38.0 2.101 2.620 109.4 21.4 15.8
2021 07 30 01 04.99 -05 01.0 2.063 2.635 113.3 20.7 15.8
2021 08 04 01 08.30 -05 28.0 2.027 2.650 117.3 19.9 15.8
2021 08 09 01 11.06 -05 58.8 1.994 2.667 121.4 18.9 15.8
2021 08 14 01 13.25 -06 33.3 1.964 2.684 125.7 17.9 15.8
2021 08 19 01 14.87 -07 11.0 1.938 2.702 130.0 16.7 15.8
2021 08 24 01 15.92 -07 51.3 1.915 2.720 134.4 15.4 15.8
2021 08 29 01 16.40 -08 33.7 1.897 2.739 138.8 14.0 15.8
2021 09 03 01 16.34 -09 17.5 1.884 2.759 143.2 12.6 15.8
2021 09 08 01 15.76 -10 01.9 1.876 2.780 147.6 11.2 15.8
2021 09 13 01 14.70 -10 45.9 1.874 2.800 151.7 9.8 15.8
2021 09 18 01 13.25 -11 28.5 1.877 2.822 155.4 8.5 15.9
2021 09 23 01 11.46 -12 09.0 1.887 2.844 158.5 7.4 15.9
2021 09 28 01 09.42 -12 46.3 1.903 2.867 160.5 6.7 16.0
2021 10 03 01 07.22 -13 19.7 1.925 2.890 161.1 6.4 16.0
2021 10 08 01 04.94 -13 48.6 1.954 2.914 160.2 6.7 16.1
2021 10 13 01 02.69 -14 12.3 1.989 2.938 158.0 7.3 16.2
2021 10 18 01 00.55 -14 30.5 2.030 2.962 154.8 8.2 16.3
2021 10 23 00 58.61 -14 43.1 2.077 2.987 151.1 9.3 16.3
2021 10 28 00 56.93 -14 50.1 2.131 3.013 146.9 10.4 16.4
2021 11 02 00 55.57 -14 51.5 2.190 3.039 142.6 11.4 16.5
2021 11 07 00 54.57 -14 47.6 2.254 3.065 138.2 12.4 16.6
2021 11 12 00 53.97 -14 38.6 2.323 3.091 133.8 13.4 16.7
2021 11 17 00 53.79 -14 25.0 2.396 3.118 129.3 14.2 16.8
2021 11 22 00 54.04 -14 07.2 2.474 3.146 124.9 14.9 16.9
2021 11 27 00 54.70 -13 45.6 2.555 3.173 120.6 15.5 17.1
2021 12 02 00 55.79 -13 20.6 2.640 3.201 116.3 16.0 17.2
2021 12 07 00 57.28 -12 52.6 2.727 3.229 112.1 16.4 17.3
2021 12 12 00 59.16 -12 22.0 2.817 3.258 107.9 16.7 17.4
2021 12 17 01 01.42 -11 49.1 2.910 3.287 103.8 16.9 17.5
2021 12 22 01 04.02 -11 14.3 3.004 3.316 99.8 17.0 17.6
2021 12 27 01 06.94 -10 38.0 3.099 3.345 95.8 17.0 17.7
2022 01 01 01 10.16 -10 00.3 3.195 3.374 91.9 16.9 17.8
2022 01 06 01 13.67 -09 21.6 3.293 3.404 88.1 16.8 17.9
2022 01 11 01 17.44 -08 42.1 3.390 3.434 84.3 16.6 18.0
2022 01 16 01 21.44 -08 02.0 3.488 3.464 80.5 16.3 18.1
2022 01 21 01 25.65 -07 21.4 3.585 3.494 76.8 15.9 18.2
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2021 CBAT
2021 May 27 (CBET 4968) Daniel W. E. Green
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