[Iaude] CBET 5353: COMET C/2024 C3

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5353
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/2024 C3 (PANSTARRS)
     R. Weryk, Department of Physics and Astronomy, University of Western
Ontario, reports the discovery of another comet in images obtained with the
Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on Feb. 9 UT
(discovery observations tabulated below); four 45-s w-band survey images
taken in 1".3-1".7 seeing showed a diffuse head of size 1".7 (full-width-at-
half-maximum) with a possible tail 3" long towards p.a. 270 degrees.

     2024 UT             R.A. (2000) Decl.       Mag.
     Feb.  9.46625   11 36 55.05   + 9 08 36.3   21.7
           9.48979   11 36 54.60   + 9 08 37.5   21.4
           9.50172   11 36 54.38   + 9 08 37.9   21.9

Weryk was then able to find several apparently asteroidal pre-discovery
images of the comet with the Pan-STARRS2 telescope on 2023 Mar. 18.3 UT (at
mag 20.9-22.2) and 2023 Dec. 17.6 (mag 21.2-22.3), as well as images taken on
2023 Mar. 25.3 with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at
Haleakala (when the comet was at mag 21.4-22.1).  Y. Ramanjooloo, Institute
for Astronomy, University of Hawaii (UH), writes that four 120-s follow-up
exposures were obtained in 1".5-1".7 seeing using the UH 2.2-m reflector at
Mauna Kea on 2024 Feb. 20.5, which show a condensed head of size about 2".1
(FWHM) and a tail about 3".9 long toward p.a. 300 deg.
     After the comet was posted on the Minor Planet Center's PCCP webpage,
H. Sato (Tokyo, Japan) reported that ten stacked CCD exposures taken remotely
on 2024 Feb. 10.4 UT with a "Deep Sky Chile" 0.51-m f/6.8 astrograph located
at Rio Hurtado, Chile, show only a stellar appearance for this comet; the
magnitude was 21.4 as measured within a circular aperture of radius 2".2.
Twelve additional 120-s exposures taken remotely by Sato on Feb. 13.7 with a
0.51-m f/6.8 astrograph at Siding Spring, NSW, Australia, show a strongly
condensed coma 4" in diameter, elongated toward p.a. 315 degrees; the
magnitude was 21.0 as measured within a circular aperture of radius 3".2.
     The available astrometry appears on MPEC 2024-D97.  The following
orbital elements by S. Nakano (Central Bureau) are from 44 observations
spanning 2023 Mar. 18-2024 Feb. 20 (mean residual 0".3).  There are no close
approaches to major planets.

                    Epoch = 2023 Oct. 23.0 TT
     T = 2023 Nov.  8.50923 TT        Peri. = 159.68486
     e = 0.4228724                    Node  = 359.70521 2000.0
     q = 6.7124425 AU                 Incl. =  22.46972
       a = 11.6307773 AU   n = 0.02484797   P =  39.67 years

                    Epoch = 2063 Sept. 3.0 TT
     T = 2063 Sept.11.62277 TT        Peri. = 160.86025
     e = 0.4354626                    Node  = 359.25241 2000.0
     q = 6.7071183 AU                 Incl. =  22.52850
       a = 11.8807342 AU   n = 0.02406795   P =  40.95 years

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 10.0 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 02 20    11 33.34   +09 16.7    5.793    6.727   159.5     3.0  20.4
2024 03 01    11 29.44   +09 25.1    5.753    6.730   169.6     1.5  20.4
2024 03 11    11 25.29   +09 33.0    5.745    6.734   174.2     0.9  20.4
2024 03 21    11 21.14   +09 38.9    5.767    6.737   165.8     2.1  20.4
2024 03 31    11 17.26   +09 41.6    5.819    6.741   155.5     3.5  20.5
2024 04 10    11 13.86   +09 40.1    5.899    6.745   145.1     4.9  20.5
2024 04 20    11 11.14   +09 33.9    6.003    6.749   134.8     6.1  20.5
2024 04 30    11 09.22   +09 22.7    6.129    6.754   124.8     7.0  20.6
2024 05 10    11 08.18   +09 06.3    6.270    6.759   115.0     7.8  20.6
2024 05 20    11 08.05   +08 44.8    6.423    6.764   105.5     8.3  20.7
2024 05 30    11 08.82   +08 18.6    6.584    6.770    96.2     8.6  20.7
2024 06 09    11 10.44   +07 47.9    6.748    6.775    87.2     8.6  20.8
2024 06 19    11 12.87   +07 13.1    6.911    6.781    78.5     8.4  20.8
2024 06 29    11 16.02   +06 34.7    7.069    6.788    69.9     8.1  20.9
2024 07 09    11 19.81   +05 53.0    7.220    6.794    61.5     7.6  20.9
2024 07 19    11 24.18   +05 08.4    7.360    6.801    53.3     6.9  21.0
2024 07 29    11 29.02   +04 21.2    7.486    6.808    45.1     6.1  21.0

2024 11 26    12 37.50   -06 00.1    7.462    6.912    52.9     6.5  21.1
2024 12 06    12 41.74   -06 44.2    7.333    6.922    61.8     7.2  21.0
2024 12 16    12 45.35   -07 25.0    7.192    6.932    70.9     7.7  21.0
2024 12 26    12 48.24   -08 02.1    7.044    6.943    80.1     8.0  21.0
2025 01 05    12 50.34   -08 35.1    6.891    6.954    89.6     8.1  20.9
2025 01 15    12 51.58   -09 03.5    6.738    6.965    99.3     8.0  20.9
2025 01 25    12 51.90   -09 27.1    6.590    6.977   109.3     7.7  20.8
2025 02 04    12 51.29   -09 45.4    6.451    6.988   119.4     7.1  20.8
2025 02 14    12 49.79   -09 58.3    6.328    7.000   129.7     6.2  20.8


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2024 CBAT
2024 February 21                 (CBET 5353)              Daniel W. E. Green