[Iaude] CBET 5387: COMET P/2022 U6 = P/2006 AH_2
quai at eps.harvard.edu
quai at eps.harvard.edu
Tue Apr 23 12:45:40 EDT 2024
Electronic Telegram No. 5387
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 P/2022 U6 = P/2006 AH_2 (SHEPPARD-THOLEN)
On 2023 Jan. 24, David J. Tholen (Institute for Astronomy, University of
Hawaii) reported the following observations as a new comet discovery made from
images obtained by Scott S. Sheppard (Carnegie Institution for Science) and
Tholen with the Subaru 8.2-m telescope on Mauna Kea, the object showing a tail
perhaps 13" long in p.a. 260 degrees in 500-s exposures that show the object
also trailed due to its motion by about 3". Sheppard found the comet while
examing the Subaru images for transneptunian objects; Tholen did the measuring
and reporting.
2022 UT R.A. (2000) Decl. Mag.
Oct. 28.45693 3 55 44.60 +26 00 19.2 22.2
28.58111 3 55 41.30 +26 00 03.9 22.2
Tholen also notified R. Weryk (Department of Physics and Astronomy, University
of Western Ontario) to ask if there might be any detections of this object
with the Pan-STARRS telescopes at Haleakala. Weryk reported on 2023 Jan. 24
that he did find faint images of the comet taken with the Pan-STARRS2 1.8-m
reflector on 2022 Oct. 19 (no magnitude given), Oct. 31 (mag 22.0-23.0), and
Nov. 16 (mag 22.0-22.6), as well as images taken with the Pan-STARRS1 1.8-m
reflector on 2022 Oct. 23 (mag 23.3-23.5); Weryk added that the comet was too
faint in the images to display any obvious activity. The Subaru and
Pan-STARRS astrometry were published on MPS 1736920 on 2023 Jan. 27.
The Minor Planet Center then apparently identified this comet with an
apparently asteroidal object discovered by the Mt. Lemmon Survey in Arizona on
2006 Jan. 2, which was designated 2006 AH_2 when announced on MPS 157964 on
2006 Jan. 8 (discovery observations tabulated below).
2006 UT R.A. (2000) Decl. Mag.
Jan. 2.36869 7 31 56.31 +15 29 06.2 20.3
2.37784 7 31 55.99 +15 29 05.4 20.2
2.40164 7 31 55.20 +15 29 04.7 20.6
2.41685 7 31 54.62 +15 29 03.6 21.1
Spacewatch observations made at Kitt Peak on 2006 Jan. 4 were also reported on
MPS 157964 (where they were identified with 2006 AH_2), but no other
observations were reported until many years later, so no orbit was established
in 2006.
In response to the object's being posted on the Minor Planet Center's
PCCP webpage, S. Deen (Simi Valley, CA, USA) wrote the Central Bureau on 2023
Jan. 24 to say that his integration of the Centaur-like orbit backwards
indicated a close approach (0.0086 AU) to Saturn on 1782 Aug. 10, changing the
orbital period from about 37.7 years to about 18.0 years. A day later, Deen
reported finding images of the comet taken on 2006 Dec. 26.6 UT with the 3.6-m
Canada-France-Hawaii Telescope at Mauna Kea in publicly available data
(acquired by H. Yee as part of a galaxy-clusters "dark-energy probe"), the
object appearing then clearly cometary with a very condensed coma (magnitudes
z = 22.2, r = 22.6, g = 22.9) and a 6" tail in p.a. 295-310 degrees. Deen's
astrometry appeared on MPS 1740759 on 2023 Feb. 14. The object was then
removed from the PCCP webpage, although it was not announced formally then as
a comet. Subsequent astrometry of this comet was acquired from 2023 Dec. 13
to 2024 Feb. 3 that were made at several observatories (with the Mt. Lemmon
survey reporting the comet as bright as mag 20.2 on 2024 Jan. 11.3 UT), and
these were published on MPS 2071229, 2079129, 2092586, and 2115948.
Eight stacked 120-s CCD exposures taken remotely by H. Sato (Bunkyo-ku,
Tokyo, Japan) with a "Deep Sky Chile" 0.51-m f/6.8 astrograph located at Rio
Hurtado, Chile, on 2023 Dec. 21.3 UT showed a moderately condensed coma 5" in
diameter with no tail; the magnitude was 20.8 as measured within a circular
aperture of radius 2".8. On 2024 Mar. 9, Tholen reported that Sheppard
obtained 300-s exposures with one of the twin 6.5-m Magellan telescopes of
Las Campanas Observatory at Cerro Manqui in 0".7 seeing on 2024 Mar. 7.04
and 8.03, showing the comet at mag 21.7 with a tail at least 5" long to the
northwest.
The following linked orbital elements by S. Nakano (Central Bureau) are
from 61 observations spanning 2006 Jan. 2-2024 Feb. 3 (mean residual 0".3).
Nakano adds that the comet passed 1.07 AU from Saturn in 1958 October.
Epoch = 2005 Sept.27.0 TT
T = 2005 Oct. 12.17657 TT Peri. = 196.18226
e = 0.4171851 Node = 261.87312 2000.0
q = 4.0019333 AU Incl. = 10.00693
a = 6.8665598 AU n = 0.05477662 P = 17.99 years
Epoch = 2023 Sept.13.0 TT
T = 2023 Aug. 24.41259 TT Peri. = 195.96727
e = 0.4170043 Node = 261.64856 2000.0
q = 3.9908604 AU Incl. = 10.01654
a = 6.8454372 AU n = 0.05503035 P = 17.91 years
Epoch = 2041 July 20.0 TT
T = 2041 July 5.57238 TT Peri. = 196.14775
e = 0.4165610 Node = 261.67532 2000.0
q = 3.9708234 AU Incl. = 10.03276
a = 6.8058935 AU n = 0.05551065 P = 17.76 years
Epoch = 2059 Mar. 8.0 TT
T = 2059 Mar. 25.41185 TT Peri. = 196.18413
e = 0.4119071 Node = 261.29836 2000.0
q = 4.0116199 AU Incl. = 10.01248
a = 6.8214055 AU n = 0.05532141 P = 17.82 years
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 12.5 and 2.5n = 8 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2024 03 31 07 41.93 +13 12.0 3.807 4.170 104.4 13.4 20.4
2024 04 10 07 45.88 +13 09.6 3.967 4.186 95.7 13.8 20.5
2024 04 20 07 51.15 +13 03.1 4.129 4.203 87.2 13.8 20.6
2024 04 30 07 57.56 +12 52.1 4.292 4.220 79.2 13.6 20.7
2024 05 10 08 04.95 +12 36.5 4.451 4.237 71.4 13.1 20.8
2024 05 20 08 13.16 +12 16.0 4.604 4.256 63.8 12.3 20.8
2024 05 30 08 22.04 +11 50.6 4.749 4.275 56.5 11.4 20.9
2024 06 09 08 31.46 +11 20.3 4.884 4.294 49.4 10.3 21.0
2024 06 19 08 41.29 +10 45.3 5.008 4.314 42.5 9.2 21.1
2024 10 17 10 40.55 -00 33.0 5.271 4.586 42.6 8.5 21.4
2024 10 27 10 48.40 -01 36.7 5.185 4.611 50.1 9.5 21.4
2024 11 06 10 55.56 -02 38.6 5.086 4.637 58.0 10.4 21.4
2024 11 16 11 01.91 -03 37.8 4.976 4.663 66.0 11.2 21.3
2024 11 26 11 07.36 -04 33.4 4.857 4.689 74.4 11.7 21.3
2024 12 06 11 11.78 -05 24.4 4.732 4.715 83.1 12.0 21.3
2024 12 16 11 15.07 -06 09.7 4.604 4.742 92.0 12.0 21.2
2024 12 26 11 17.13 -06 48.2 4.477 4.769 101.3 11.7 21.2
2025 01 05 11 17.90 -07 18.8 4.356 4.796 110.9 11.0 21.1
2025 01 15 11 17.34 -07 40.4 4.245 4.823 120.8 10.1 21.1
2025 01 25 11 15.51 -07 52.3 4.148 4.851 130.9 8.8 21.1
2025 02 04 11 12.52 -07 53.9 4.071 4.878 141.2 7.3 21.1
2025 02 14 11 08.58 -07 45.3 4.017 4.906 151.4 5.5 21.0
2025 02 24 11 04.00 -07 27.4 3.989 4.935 160.8 3.8 21.1
2025 03 06 10 59.13 -07 01.6 3.991 4.963 167.1 2.6 21.1
2025 03 16 10 54.36 -06 30.3 4.023 4.991 165.3 2.9 21.1
2025 03 26 10 50.06 -05 55.9 4.084 5.020 157.4 4.4 21.2
2025 04 05 10 46.54 -05 21.2 4.174 5.049 147.9 6.0 21.2
2025 04 15 10 44.03 -04 48.8 4.288 5.078 138.0 7.6 21.3
2025 04 25 10 42.66 -04 20.5 4.423 5.107 128.2 8.9 21.4
2025 05 05 10 42.49 -03 57.8 4.576 5.136 118.6 9.9 21.5
2025 05 15 10 43.51 -03 41.9 4.742 5.165 109.3 10.6 21.6
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2024 CBAT
2024 April 23 (CBET 5387) Daniel W. E. Green
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