[Iaude] CBET 5404: COMET C/2023 A3
quai at eps.harvard.edu
quai at eps.harvard.edu
Mon Jun 17 16:47:48 EDT 2024
Electronic Telegram No. 5404
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/2023 A3 (TSUCHINSHAN-ATLAS)
The following revised orbital elements by S. Nakano (Central Bureau) are
from 4341 observations spanning 2022 Apr. 9-2024 June 6 (mean residual 0".4),
with corresponding "original" and "future" values of 1/a = -0.000012 and
-0.000053 (+/- 0.000001) AU**-1, respectively. G. V. Williams writes that he
obtained orbital elements from 3987 observations covering the same arc as
Nakano's orbit and obtained original 1/a = -0.0000002 +/- 0.0000004 AU**-1,
which is indistinguishable from a parabolic orbit.
Epoch = 2024 Oct. 17.0 TT
T = 2024 Sept. 27.74013 TT Peri. = 308.49328
e = 1.0000949 Node = 21.55949 2000.0
q = 0.3914109 AU Incl. = 139.11049
Selected visual total-magnitude and coma-diameter estimates reported to
the Central Bureau: Jan. 7.26 UT, 12.7, 0'.8 (J. J. Gonzalez, Leon, Spain,
0.20-m reflector); 20.23, 13.2, 0'.3 (W. Hasubick, Buchloe, Germany, 44-cm
reflector); Apr. 8.90, 10.6, 1'.2 (Gonzalez); 11.19, 10.7, 2'.5 (M. Goiato,
Aracatuba, 0.22-m reflector); 28.12, 10.0, 1' (W. Souza, Atibaia, SP, Brazil,
20x80 binoculars); 30.99, 10.7, 1'.7 (Hasubick); May 3.52, 10.5, 2'.3 (S.
Yoshida, Gunma, Japan, 0.40-m reflector); 6.95, 10.9, 1'.1 (Gonzalez); 22.81,
10.5, 3' (V. Gonano, Udine, Italy, 20x80 binoculars); 29.93, 10.9, 1'.0
(Gonzalez); 31.94, 10.1, 1' (Souza); June 1.94, 11.0, 1'.0 (Gonzalez); 4.50,
10.6, 2' (K. Yoshimoto, Yamaguchi, Japan, 20x100 binoculars); 6.82, 10.2,
1'.5 (Gonano); 10.94, 10.8, 1'.0 (Gonzalez); 13.88, 10.7, 2' (Gonano). In
May and June, visual observers have reported a short eastward tail,
generally 5'-15' long. Photographs in recent weeks show the tail to be
significantly dusty rather than gassy.
The following ephemeris from Nakano's orbital elements above uses
magnitude parameters H = 6.0, 2.5n = 7.5. The comet's brightness increase
has slowed in recent weeks, and reliable total-magnitude estimates are likely
to become few in number later in August, as the comet then reaches small
solar elongations for a couple of months surrounding perihelion and the time
of expected peak brightness. J. Marcus (St. Louis, MO, USA) writes that his
modeling for forward-scattering brightness variations in comets close to the
sun (cf. Marcus 2007, ICQ 29, 119ff) suggests that, if comet C/2023 A3
survives to perihelion and does not split, there could be a forward-scattering
enhancement of 1 mag or more during Oct. 3-17, with a peak around the time
of the comet's minimum scattering angle (7.0 degrees) on Oct. 9.8 UT of
perhaps several magnitudes. But the baseline lightcurve predicted for October
(aside from forward scattering in the comet's coma) is highly uncertain at
the present time. Note that 7.5 log r (not 10 log r) represents well the
average total magnitudes of most long-period comets over their paths through
the inner solar system, which is why these circulars use 8 log r as a
standard parameter for ephemerides of such comets.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2024 06 19 11 30.74 +03 02.2 1.900 2.062 84.2 29.4 9.8
2024 06 24 11 24.11 +02 58.3 1.931 1.985 77.9 30.0 9.7
2024 06 29 11 18.33 +02 50.3 1.960 1.907 71.9 30.4 9.6
2024 07 04 11 13.33 +02 38.4 1.987 1.828 66.1 30.6 9.5
2024 07 09 11 09.02 +02 23.0 2.009 1.748 60.4 30.4 9.3
2024 07 14 11 05.31 +02 04.3 2.027 1.666 55.0 30.0 9.2
2024 07 19 11 02.12 +01 42.5 2.038 1.583 49.6 29.3 9.0
2024 07 24 10 59.35 +01 18.0 2.043 1.498 44.5 28.4 8.9
2024 07 29 10 56.93 +00 50.9 2.040 1.412 39.4 27.2 8.7
2024 08 03 10 54.78 +00 21.1 2.029 1.324 34.5 25.7 8.5
2024 08 08 10 52.82 -00 11.1 2.008 1.234 29.7 24.0 8.2
2024 08 13 10 50.95 -00 45.7 1.977 1.143 25.0 22.0 7.9
2024 08 18 10 49.10 -01 22.7 1.935 1.050 20.6 19.8 7.6
2024 08 23 10 47.17 -02 01.8 1.880 0.955 16.6 17.6 7.2
2024 08 28 10 45.08 -02 43.0 1.810 0.859 13.3 15.7 6.8
2024 09 02 10 42.77 -03 25.9 1.724 0.762 11.4 15.2 6.3
2024 09 07 10 40.21 -04 09.8 1.619 0.665 11.7 17.9 5.7
2024 09 12 10 37.55 -04 52.9 1.492 0.571 14.1 25.5 5.0
2024 09 17 10 35.44 -05 31.8 1.337 0.487 17.7 38.8 4.3
2024 09 22 10 35.95 -05 59.7 1.152 0.422 21.2 59.2 3.5
2024 09 27 10 44.39 -06 05.5 0.940 0.392 23.0 87.4 2.8
2024 10 02 11 11.39 -05 35.1 0.726 0.408 20.4 121.3 2.4
2024 10 07 12 12.20 -04 08.4 0.552 0.465 9.8 158.6 2.2
2024 10 12 13 52.89 -01 28.0 0.473 0.545 12.3 157.0 2.4
2024 10 17 15 37.41 +01 16.0 0.517 0.637 33.9 119.2 3.1
2024 10 22 16 48.93 +02 47.1 0.643 0.733 47.3 92.4 4.0
2024 10 27 17 32.16 +03 26.6 0.805 0.830 53.7 74.9 4.9
2024 11 01 17 59.55 +03 43.7 0.978 0.926 56.1 62.8 5.7
2024 11 06 18 18.40 +03 52.3 1.152 1.022 56.3 53.9 6.4
2024 11 11 18 32.40 +03 58.3 1.324 1.115 55.4 46.9 7.0
2024 11 16 18 43.47 +04 04.0 1.491 1.207 53.8 41.4 7.5
2024 11 21 18 52.67 +04 10.7 1.653 1.297 51.7 36.7 7.9
2024 11 26 19 00.62 +04 19.0 1.808 1.386 49.4 32.7 8.3
2024 12 01 19 07.71 +04 29.1 1.958 1.472 46.9 29.3 8.7
2024 12 06 19 14.16 +04 41.4 2.101 1.557 44.4 26.3 9.1
2024 12 11 19 20.12 +04 55.9 2.238 1.641 41.8 23.6 9.4
2024 12 16 19 25.69 +05 12.5 2.367 1.723 39.3 21.2 9.6
2024 12 21 19 30.94 +05 31.2 2.490 1.804 37.0 19.1 9.9
2024 12 26 19 35.93 +05 52.1 2.606 1.883 34.8 17.3 10.1
2024 12 31 19 40.68 +06 15.1 2.715 1.962 32.8 15.7 10.4
2025 01 05 19 45.22 +06 40.2 2.817 2.039 31.1 14.4 10.6
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2024 CBAT
2024 June 17 (CBET 5404) Daniel W. E. Green
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