[Iaude] CBET 5300: COMET C/2023 Q1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5300
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 Q1 (PANSTARRS)
     P. Veres, Minor Planet Center, writes that he linked together five
previously unlinked sets of one-night observations spanning Aug. 20-Sept. 20
that were in the MPC's "isolated tracklet file".  After noticing a nearly
parabolic orbit for the fit of these observations, Veres asked R. Weryk
(Department of Physics and Astronomy, University of Western Ontario) to check
the images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at
Haleakala.  Weryk reports finding a weakly active comet on two nights:  On
Aug. 20.6 UT, three 45-s w-band survey images show a very condensed head of
size 1".0 (full-width-at-half-maximum) in 0".85 seeing with no tail.  Four
45-s w-band survey images taken on Sept. 17.4 show a very condensed head of
size 1".4 (FWHM) in 1".1 seeing with no tail.  Weryk also identified
pre-discovery Pan-STARRS1 images from July 25.6 (mag 22.5-23.0) and
Pan-STARRS2 images from July 26.6 (mag 22.1) and 29.6 (mag 22.7-22.8).  The
discovery observations are tabulated below.

     2023 UT             R.A. (2000) Decl.       Mag.
     Aug. 20.55451    0 40 52.32   - 0 49 25.5   22.0
          20.56726    0 40 52.05   - 0 49 24.9   22.3
          20.57997    0 40 51.75   - 0 49 24.3   22.0

After the comet was posted on the MPC's PCCP webpage, H. Sato (Bunkyo-ku,
Tokyo, Japan) reported that twenty-three stacked 60-s CCD exposures obtained
on Sept. 23.7 UT with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW,
Australia, show a strongly condensed coma 6" in diameter with no tail; the
magnitude was 20.4 as measured within a circular aperture of radius 4".9.
     The available astrometry appears on MPEC 2023-T8.  The following
parabolic orbital elements by S. Nakano (Central Bureau) are from 46
observations spanning 2023 July 25-Sept. 27 (mean residual 0".5).  The comet
will pass 2.75 AU from Jupiter on 2024 Jan. 19 UT.

     T = 2024 Dec.  2.31277 TT        Peri. =  84.43277
                                      Node  =   7.16416 2000.0
     q = 2.5798246 AU                 Incl. =  36.64700

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.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2023 09 13    00 29.65   -00 43.5    4.130    5.100   162.7     3.4  20.2
2023 09 23    00 23.35   -00 44.3    4.026    5.024   173.6     1.3  20.1
2023 10 03    00 16.58   -00 44.8    3.952    4.949   173.8     1.2  20.0
2023 10 13    00 09.73   -00 43.4    3.911    4.873   162.8     3.5  20.0
2023 10 23    00 03.24   -00 38.3    3.899    4.797   151.5     5.7  19.9
2023 11 02    23 57.51   -00 27.8    3.916    4.722   140.3     7.7  19.9
2023 11 12    23 52.87   -00 11.0    3.956    4.647   129.3     9.5  19.8
2023 11 22    23 49.55   +00 13.2    4.016    4.571   118.6    10.9  19.8
2023 12 02    23 47.71   +00 45.2    4.089    4.496   108.3    12.0  19.8
2023 12 12    23 47.37   +01 25.1    4.171    4.422    98.3    12.7  19.8
2023 12 22    23 48.53   +02 12.8    4.256    4.347    88.7    13.1  19.8
2024 01 01    23 51.10   +03 08.2    4.341    4.273    79.5    13.1  19.7
2024 01 11    23 54.99   +04 10.9    4.421    4.199    70.7    12.8  19.7


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 5300)              Daniel W. E. Green