[Iaude] CBET 5301: COMET C/2023 R2

quai at eps.harvard.edu quai at eps.harvard.edu
Mon Oct 2 23:08:38 EDT 2023


                                                  Electronic Telegram No. 5301
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 R2 (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 (discovery
observations tabulated below).  The object appeared only marginally cometary
in the discovery images, but three 60-s gri-band follow-up images obtained
on Sept. 11.61 UT with the 3.6-m Canada-France-Hawaii Telescope on Mauna Kea
(queue observer L. Wells) confirm the cometary nature; there is a very
condensed coma of size 1".6 (full-width-at-half-maximum) in 1".0 seeing with
a broad tail > 4" long spanning p.a. 230-300 degrees.

     2023 UT             R.A. (2000) Decl.       Mag.
     Sept.10.58966    3 15 42.86   + 0 29 27.3   20.6
          10.60129    3 15 42.82   + 0 29 23.2   20.6
          10.61287    3 15 42.79   + 0 29 18.8   20.6

Y. Ramanjooloo (University of Hawaii) adds that four additional 45-s w-band
Pan-STARRS2 images obtained on Sept. 19.6 UT in 1".5 seeing show a diffuse
coma of size 2".5 (FWHM) with no apparent tail.  After the comet was posted
on the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan)
reported that eight stacked 120-s CCD exposures obtained at Siding Spring
on Sept. 13.78 with a 0.51-m f/6.8 astrograph show a strongly condensed coma
8" in diameter with a hint of a tail 5" long toward p.a. 150 degrees; the
magnitude was 19.9 as measured within a circular aperture of radius 4".9.
     The available astrometry appears on MPEC 2023-T7.  The following
parabolic orbital elements by S. Nakano (Central Bureau) are from 120
observations spanning 2023 Sept. 10-29 (mean residual 0".4).  The comet
passed 1.09 AU from Jupiter on 2023 June 29 UT.

     T = 2024 Aug. 12.48466 TT        Peri. = 337.11135
                                      Node  = 189.04584 2000.0
     q = 0.9080865 AU                 Incl. =  30.78356

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 11.5 and 2.5n = 8 for the
magnitudes.  The comet will be on the far side of the sun at perihelion.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2023 09 13    03 15.59   +00 14.6    3.959    4.566   121.5    10.8  19.8
2023 09 23    03 14.12   -00 52.5    3.741    4.464   130.9     9.8  19.6
2023 10 03    03 11.07   -02 07.2    3.543    4.360   140.3     8.4  19.4
2023 10 13    03 06.41   -03 27.5    3.369    4.256   149.1     6.9  19.2
2023 10 23    03 00.28   -04 50.0    3.223    4.151   155.9     5.6  19.0
2023 11 02    02 52.93   -06 10.3    3.106    4.045   158.3     5.2  18.8
2023 11 12    02 44.80   -07 23.8    3.021    3.938   154.6     6.2  18.7
2023 11 22    02 36.45   -08 25.7    2.966    3.830   146.7     8.1  18.5
2023 12 02    02 28.51   -09 12.4    2.939    3.721   137.0    10.4  18.4
2023 12 12    02 21.55   -09 41.8    2.935    3.611   126.7    12.6  18.3
2023 12 22    02 16.09   -09 53.2    2.950    3.500   116.4    14.6  18.2
2024 01 01    02 12.47   -09 47.7    2.977    3.387   106.3    16.2  18.1
2024 01 11    02 10.86   -09 27.1    3.010    3.273    96.7    17.4  18.0
2024 01 21    02 11.37   -08 53.6    3.045    3.158    87.5    18.1  17.9
2024 01 31    02 13.94   -08 09.5    3.076    3.042    78.8    18.5  17.8
2024 02 10    02 18.52   -07 16.9    3.100    2.925    70.7    18.6  17.7
2024 02 20    02 25.02   -06 17.8    3.112    2.806    63.0    18.3  17.6


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

                         (C) Copyright 2023 CBAT
2023 October 3                   (CBET 5301)              Daniel W. E. Green



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