[Iaude] CBET 5418: COMET C/2024 L5

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5418
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 L5 (ATLAS)
     An apparently asteroidal object discovered on CCD images taken on June
14.94-14.96 UT with a 0.5-m f/2 Schmidt reflector at Sutherland, South Africa,
in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS)
search program has been found to show cometary appearance by CCD
astrometrists elsewhere.  The discovery observations are tabulated below:

     2024 UT             R.A. (2000) Decl.       Mag.
     June 14.94445   17 08 35.68   -38 02 46.9   17.6
          14.94764   17 08 35.21   -38 02 46.6   17.6
          14.95319   17 08 34.36   -38 02 45.8   17.7
          14.96322   17 08 32.87   -38 02 45.3   17.7

H. Sato (Bunkyo-ku, Tokyo, Japan) writes that seven stacked 60-s exposures
taken remotely on June 16.66 UT with a 0.51-m f/6.8 astrograph located at
Siding Spring, NSW, Australia, show a strongly condensed object with an outer
coma 10" in diameter and no tail; the magnitude was 17.1 as measured within a
circular aperture of radius 5".4.  T. Prystavski (Lviv, Ukraine) notes that
images obtained on June 26.4 with a 0.51-m f/6.8 Corrected Dall-Kirkham
telescope at Siding Spring show the comet to be only a star-like object of
mag 17.6 in a dense star field.  F. D. Romanov (Yuzhno-Morskoy, Nakhodka,
Russia) relates that seventeen stacked 60-s exposures taken remotely on July
18.1 with an iTelescope 0.5-m f/6.8 reflector (+ Luminance filter) at the
"Deep Sky Chile" observatory (Rio Hurtado Valley, Chile) show a condensed
coma 9" in diameter with a straight 7" tail in p.a. 80 deg; the magnitude
was measured as 17.8.
     The available astrometry appears on MPEC 2024-O15.  The following orbital
elements by S. Nakano (Central Bureau) are from 142 observations spanning 2024
June 14-July 18 (mean residual 0".4) and indicate that the comet passed 0.0049
AU from Saturn on 2022 Jan. 24 UT.  Prior to that close encounter, the comet
had orbital elements T = 1883 July 11, q = 7.240 AU, e = 0.738, Peri. = 250.8
degrees, Node = 137.4 deg, i = 157.6 deg (equinox J2000.0), a = 27.65 AU, P =
145.4 years.  The comet will pass 0.60 AU from Jupiter on 2026 Aug. 18 UT.
The corresponing "future" value of 1/a is -0.009156 (+/- 0.000238) AU**-1.

                    Epoch = 2025 Mar. 26.0 TT
     T = 2025 Mar. 10.39265 TT        Peri. = 290.51680
     e = 1.0373672                    Node  = 139.17750 2000.0
     q = 3.4323213 AU                 Incl. = 166.57327

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 9.5 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 06 19    16 58.58   -37 55.1    3.243    4.220   161.7     4.3  17.1
2024 06 29    16 34.48   -37 17.9    3.249    4.168   151.1     6.8  17.0
2024 07 09    16 12.38   -36 19.7    3.300    4.118   138.6     9.4  17.0
2024 07 19    15 53.32   -35 08.7    3.390    4.068   125.8    11.7  17.0
2024 07 29    15 37.72   -33 53.5    3.508    4.020   113.3    13.4  17.1
2024 08 08    15 25.56   -32 41.3    3.648    3.974   101.4    14.5  17.1
2024 08 18    15 16.53   -31 36.5    3.797    3.928    89.9    14.9  17.2
2024 08 28    15 10.21   -30 41.6    3.950    3.885    79.0    14.8  17.2
2024 09 07    15 06.16   -29 57.3    4.097    3.843    68.4    14.1  17.2
2024 09 17    15 03.97   -29 23.5    4.233    3.802    58.3    13.0  17.3
2024 09 27    15 03.27   -28 59.3    4.351    3.763    48.5    11.5  17.3

2024 12 26    15 19.42   -29 52.8    4.194    3.504    40.4    10.5  17.0
2025 01 05    15 19.05   -30 13.5    4.032    3.486    50.3    12.5  16.9
2025 01 15    15 17.06   -30 34.2    3.848    3.471    60.5    14.3  16.7
2025 01 25    15 12.97   -30 53.1    3.647    3.458    71.2    15.6  16.6
2025 02 04    15 06.21   -31 07.8    3.436    3.448    82.5    16.5  16.5
2025 02 14    14 56.16   -31 14.2    3.221    3.440    94.3    16.6  16.3
2025 02 24    14 42.22   -31 06.7    3.014    3.435   106.9    16.0  16.2
2025 03 06    14 23.96   -30 36.7    2.823    3.433   120.3    14.4  16.0
2025 03 16    14 01.40   -29 34.4    2.663    3.433   134.3    12.0  15.9
2025 03 26    13 35.36   -27 50.7    2.546    3.435   148.5     8.7  15.8
2025 04 05    13 07.48   -25 22.5    2.482    3.441   160.4     5.6  15.8
2025 04 15    12 39.99   -22 17.6    2.480    3.449   162.2     5.1  15.8
2025 04 25    12 14.95   -18 53.0    2.540    3.459   151.9     7.9  15.8
2025 05 05    11 53.70   -15 29.3    2.655    3.472   138.2    11.2  15.9
2025 05 15    11 36.71   -12 22.5    2.815    3.488   124.4    13.8  16.1
2025 05 25    11 23.79   -09 41.4    3.008    3.506   111.3    15.6  16.2
2025 06 04    11 14.45   -07 28.4    3.222    3.526    99.0    16.5  16.4
2025 06 14    11 08.09   -05 42.0    3.445    3.549    87.5    16.6  16.6


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

                         (C) Copyright 2024 CBAT
2024 July 20                     (CBET 5418)              Daniel W. E. Green