[Iaude] CBET 5293: COMET C/2023 R1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5293
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 R1 (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 Sept. 7
(discovery observations tabulated below).  Four 45-s w-band survey images
taken in 1" seeing how a condensed head of size 1".5 (full-width-at-half-
maximum) with no tail.

     2023 UT             R.A. (2000) Decl.       Mag.
     Sept. 7.57001    0 59 56.43   +31 45 19.4   20.1
           7.58095    0 59 56.01   +31 45 19.2   20.3
           7.59183    0 59 55.58   +31 45 18.8   20.5
           7.60272    0 59 55.15   +31 45 18.7   19.7

Weryk identified the comet in numerous pre-discovery Pan-STARRS images on nine
nights dating back to July 29.6 UT (when mag 21.6 was measured).  Four 45-s
w-band survey images taken on July 30.6 in 1".3 seeing show a condensed head
of size 1".6 (FWHM) and magnitude 20.9-21.0 and no tail.  Sixteen stacked
60-s CCD exposures taken remotely on Sept. 8.3 by H. Sato (Bunkyo-ku, Tokyo,
Japan) using a 0.51-m f/6.8 astrograph located at the Utah Desert Remote
Observatory (near Beryl Junction, UT, USA) show only a stellar appearance;
the magnitude was 19.4 as measured within a circular aperture of radius 4".9.
     The available astrometry appears on MPEC 2023-R197.  The following
parabolic orbital elements by S. Nakano (Central Bureau) are from 89
observations spanning 2023 July 29-Sept. 14 (mean residual 0".4).

     T = 2026 Apr. 14.41232 TT        Peri. = 144.33367
                                      Node  =  62.54725 2000.0
     q = 3.5691365 AU                 Incl. = 149.31413

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 7.5 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2023 08 04    01 16.83   +31 15.5    8.468    8.708   100.4     6.6  19.7
2023 08 14    01 13.12   +31 32.0    8.249    8.645   109.8     6.3  19.6
2023 08 24    01 08.42   +31 42.6    8.042    8.582   119.3     5.9  19.5
2023 09 03    01 02.80   +31 46.3    7.851    8.518   128.6     5.3  19.4
2023 09 13    00 56.34   +31 41.9    7.683    8.454   137.7     4.6  19.3
2023 09 23    00 49.23   +31 28.8    7.540    8.391   146.0     3.8  19.3
2023 10 03    00 41.68   +31 06.7    7.427    8.327   152.5     3.2  19.2
2023 10 13    00 33.96   +30 36.0    7.346    8.263   155.3     2.9  19.2
2023 10 23    00 26.38   +29 57.6    7.298    8.200   153.3     3.1  19.1
2023 11 02    00 19.20   +29 13.3    7.284    8.136   147.2     3.8  19.1
2023 11 12    00 12.67   +28 25.1    7.300    8.072   138.8     4.6  19.1
2023 11 22    00 06.99   +27 35.3    7.345    8.008   129.4     5.5  19.1
2023 12 02    00 02.29   +26 46.3    7.412    7.944   119.5     6.2  19.0
2023 12 12    23 58.62   +26 00.2    7.497    7.880   109.4     6.8  19.0
2023 12 22    23 56.01   +25 18.7    7.595    7.816    99.4     7.1  19.0
2024 01 01    23 54.40   +24 43.1    7.698    7.751    89.5     7.3  19.0


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

                         (C) Copyright 2023 CBAT
2023 September 15                (CBET 5293)              Daniel W. E. Green