[Iaude] CBET 5392: COMET C/2024 G6

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5392
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 G6 (ATLAS)
     A Fitzsimmons reported to the Minor Planet Center the discovery of a
comet on CCD images taken on Apr. 10 UT with a 0.5-m f/2 Schmidt reflector at
Rio Hurtado, Chile, in the course of the "Asteroid Terrestrial-Impact Last
Alert System" (ATLAS) search program, noting that three 110-s exposures show a
head of size 5".9 (full-width-at-half-maximum) in 4".6 seeing with a faint
tail-like feature extending 13" in p.a. 120 degrees (but adding that the field
is very crowded "and background contamination cannot be ruled out").  The
discovery observations are tabulated below:

     2024 UT             R.A. (2000) Decl.       Mag.
     Apr. 10.34864   18 17 04.11   -47 41 51.7   19.1
          10.37172   18 17 03.53   -47 41 52.0   18.8
          10.39467   18 17 02.98   -47 41 51.8   18.8

After the comet was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists also commented on the cometary appearance, including the
following reports sent to the Central Bureau.  S. Deen (Simi Valley, CA, USA)
reports that he obtained images of this comet with a 0.43-m reflector at Rio
Hurtado, Chile, on Apr. 16.1-16.3 UT that show a very condensed head of size
2" (FWHM) in 1".5 seeing with magnitude V = 18.7-18.8; there was also a
possible faint tail extending 4".5 in p.a. 160-170 degrees.  Ten stacked 60-s
exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) using a 0.51-m
f/6.8 astrograph located at Siding Spring, NSW, Australia, on Apr. 16.8 show a
strongly condensed coma 8" in diameter with no tail; the magnitude was 19.0 as
measured within a circular aperture of radius 4".3.  Twelve 180-s stacked
exposures taken on Apr. 19.03-19.05 by A. Aletti, L. Buzzi, F. Bellini, and G.
Galli with a 0.36-m f/8.4 reflector at Hakos, Namibia, show a slightly
condensed coma 5" wide extended toward the north; the magnitude was measured
to be 19.0-19.1.  T. Prystavski (Lviv, Ukraine) writes that images obtained
with a 0.51-m f/6.8 Corrected Dall-Kirkham telescope located at Rio Hurtado
on Apr. 20.3 show a very short, straight tail 0'.14 long in p.a. 322 degrees;
the very condensed coma had a size of 0'.1 and total magnitude 19.0.
     The available astrometry appears on MPEC 2024-J134.  The following
parabolic orbital elements by S. Nakano (Central Bureau) are from 41
observations spanning 2024 Apr. 10-May 4 (mean residual 0".6).  There are no
close approaches to any major planets.

     T = 2026 Feb. 20.83018 TT        Peri. =  23.39027
                                      Node  = 250.95648 2000.0
     q = 6.4346756 AU                 Incl. = 120.44937

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 7.0 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 05 10    17 58.54   -47 38.4    7.027    7.764   134.1     5.4  18.4
2024 05 20    17 49.71   -47 25.8    6.895    7.728   143.1     4.5  18.3
2024 05 30    17 40.00   -47 04.5    6.791    7.692   150.8     3.7  18.2
2024 06 09    17 29.78   -46 33.6    6.718    7.657   156.0     3.1  18.2
2024 06 19    17 19.50   -45 52.8    6.678    7.622   156.7     3.0  18.2
2024 06 29    17 09.60   -45 02.9    6.671    7.587   152.4     3.6  18.2
2024 07 09    17 00.46   -44 05.3    6.697    7.553   145.1     4.4  18.2
2024 07 19    16 52.42   -43 02.2    6.752    7.519   136.3     5.4  18.2
2024 07 29    16 45.66   -41 55.9    6.834    7.486   126.8     6.2  18.2
2024 08 08    16 40.29   -40 48.6    6.937    7.453   117.0     7.0  18.2
2024 08 18    16 36.35   -39 42.5    7.057    7.420   107.2     7.5  18.2
2024 08 28    16 33.78   -38 39.0    7.189    7.388    97.4     7.8  18.2
2024 09 07    16 32.50   -37 39.2    7.326    7.356    87.7     7.9  18.3
2024 09 17    16 32.39   -36 43.9    7.464    7.324    78.1     7.7  18.3
2024 09 27    16 33.33   -35 53.1    7.597    7.293    68.7     7.4  18.3
2024 10 07    16 35.18   -35 07.0    7.721    7.262    59.3     6.8  18.3
2024 10 17    16 37.80   -34 25.2    7.831    7.232    50.1     6.1  18.3


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

                         (C) Copyright 2024 CBAT
2024 May 10                      (CBET 5392)              Daniel W. E. Green