[Iaude] COMET C/2023 X2
quai at eps.harvard.edu
quai at eps.harvard.edu
Mon Dec 11 22:30:32 EST 2023
Electronic Telegram No. 5323
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 X2 (LEMMON)
R. Weryk, Department of Physics and Astronomy, University of Western
Ontario, reports the discovery of another comet in images obtained with the
Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Dec. 4.3 UT, in
which four 45-s w-band survey images taken in 1".0 seeing show a condensed
head of size 1".7 (full-width-at-half-maximum) with a tail about 6" long
toward p.a. 210 degrees. The object was reported independently as an
apparently asteroidal object on images obtained shortly thereafter (Dec. 4.4)
with the 1.5-m Mt. Lemmon Survey reflector, but the Mt. Lemmon observations
were posted to the Minor Planet Center's NEOCP website before the Pan-STARRS1
observations arrived, and Weryk immediately noticed the identity. The
discovery observations are tabulated below.
2023 UT R.A. (2000) Decl. Mag. Observer
Dec. 4.31664 4 13 21.52 +16 02 18.3 20.5 Pan-STARRS1
4.33254 4 13 20.94 +16 02 20.6 20.8 "
4.34673 4 13 20.41 +16 02 22.5 20.6 "
4.35197 4 13 20.17 +16 02 22.6 19.7 Mt. Lemmon Survey
4.35709 4 13 19.97 +16 02 23.2 20.2 "
4.36088 4 13 19.89 +16 02 24.2 20.5 Pan-STARRS1
4.36221 4 13 19.78 +16 02 24.1 20.1 Mt. Lemmon Survey
4.36733 4 13 19.60 +16 02 24.4 19.8 "
Pan-STARRS1 observations made in Oct. 12.5 UT (when the comet was at mag
21.3-21.6) were subsequently identified in MPC's "isolated tracklet file",
together with observations on Oct. 17.5 (mag 21.5-21.8) made with the
Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala. Weryk then found
additional Pan-STARRS2 observations on Aug. 18.6 (mag 21.7-22.1), Sept. 20.6
(mag 21.4-21.8), and Oct. 7.5 (mag 21.1-21.5). Y. Ramanjooloo (Institute for
Astronomy, University of Hawaii) writes that four 45-s w-band Pan-STARRS2
images obtained on Dec. 7.33-7.37 show a diffuse and faint 2".2 tail towards
p.a. 227 degrees, with a condensed coma of size 2".1.
After the comet was posted to the MPC's PCCP webpage, other CCD
astrometrists commented on the object's appearance. Ten stacked 120-s
exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.43-m
f/6.8 astrograph located at the Utah Desert Remote Observatory (near Beryl
Junction, UT, USA) on Dec. 6.2 UT show only a stellar appearance; the
magnitude was 20.2 as measured within a circular aperture of radius 3".8.
Ninety-nine stacked 30-s exposures taken by L. Buzzi and G. Galli at Varese,
Italy, with a 0.84-m f/3.5 reflector on Dec. 7.0 (measured by A. Aletti,
Buzzi, and Galli) show a condensed coma 7" wide (mag 20.5) with a faint,
straight tail 12" long in p.a. 265 degrees.
The available astrometry appears on MPEC 2023-X226. The following
orbital elements by S. Nakano (Central Bureau) are from 75 observations
spanning 2023 Aug. 18-Dec. 11 (mean residual 0".3). The corresponding
"original" and "future" values of 1/a are +0.000333 and +0.000712 (+/-
0.000044) AU**-1, respectively. The comet will pass 1.82 AU from Jupiter
on 2024 Aug. 9 UT.
Epoch = 2025 Dec. 31.0 TT
T = 2025 Dec. 28.47605 TT Peri. = 64.79176
e = 0.9997663 Node = 66.30112 2000.0
q = 5.0889123 AU Incl. = 76.97848
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 8.5 and 2.5n = 8 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2023 12 02 04 14.78 +15 57.0 6.541 7.521 173.1 0.9 19.6
2023 12 12 04 08.69 +16 20.2 6.522 7.471 163.3 2.2 19.6
2023 12 22 04 02.86 +16 44.9 6.536 7.421 152.2 3.5 19.5
2024 01 01 03 57.55 +17 11.1 6.581 7.371 141.0 4.8 19.5
2024 01 11 03 52.97 +17 39.0 6.651 7.321 129.9 5.9 19.5
2024 01 21 03 49.29 +18 08.9 6.744 7.272 119.0 6.8 19.5
2024 01 31 03 46.61 +18 40.9 6.852 7.223 108.4 7.4 19.5
2024 02 10 03 44.98 +19 14.9 6.970 7.174 98.0 7.8 19.6
2024 02 20 03 44.39 +19 50.9 7.093 7.125 87.9 8.0 19.6
2024 03 01 03 44.81 +20 28.9 7.215 7.077 78.0 7.9 19.6
2024 03 11 03 46.18 +21 08.7 7.332 7.029 68.5 7.6 19.6
2024 03 21 03 48.42 +21 50.1 7.438 6.981 59.2 7.0 19.6
2024 03 31 03 51.44 +22 33.1 7.530 6.933 50.2 6.4 19.6
2024 07 29 04 54.21 +32 34.2 6.980 6.386 50.8 7.1 19.2
2024 08 08 04 58.67 +33 34.6 6.802 6.343 59.2 7.9 19.1
2024 08 18 05 02.45 +34 37.8 6.613 6.301 67.8 8.6 19.0
2024 08 28 05 05.41 +35 44.2 6.416 6.258 76.5 9.0 18.9
2024 09 07 05 07.34 +36 54.0 6.214 6.217 85.5 9.3 18.8
2024 09 17 05 08.08 +38 07.3 6.012 6.175 94.6 9.3 18.7
2024 09 27 05 07.43 +39 23.5 5.815 6.135 104.0 9.1 18.6
2024 10 07 05 05.21 +40 42.1 5.627 6.094 113.5 8.7 18.5
2024 10 17 05 01.25 +42 01.4 5.453 6.055 123.1 7.9 18.4
2024 10 27 04 55.49 +43 19.6 5.299 6.016 132.5 7.0 18.4
2024 11 06 04 47.93 +44 33.9 5.170 5.977 141.4 5.9 18.3
2024 11 16 04 38.75 +45 41.5 5.069 5.939 149.1 4.9 18.2
2024 11 26 04 28.31 +46 39.5 4.999 5.901 153.9 4.2 18.2
2024 12 06 04 17.10 +47 25.9 4.962 5.865 154.2 4.2 18.1
2024 12 16 04 05.81 +47 59.8 4.958 5.828 149.7 4.9 18.1
2024 12 26 03 55.08 +48 21.9 4.985 5.793 142.2 6.0 18.1
2025 01 05 03 45.54 +48 34.3 5.039 5.758 133.3 7.1 18.1
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2023 CBAT
2023 December 12 (CBET 5323) Daniel W. E. Green
More information about the Iaude
mailing list