[Iaude] CBET 5402: COMET C/2024 L1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5402
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 L1 (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, though it was
initially reported as apparently asteroidal.  P. Veres, Minor Planet Center,
noticed the object in the MPC's "isolated tracklet file" and notified Weryk
about the object's Centaur-like orbit, causing Weryk to look closely at the
images and find cometary activity.  Eight stacked 45-s w-band survey images
taken on the discovery night in 1".0-1".2 seeing (and tabulated below) show
a condensed head of size 1".6 (full-width-at-half-maximum) and no tail.

     2024 UT             R.A. (2000) Decl.       Mag.
     June  1.28090   15 51 20.89   +26 47 49.8   21.6
           1.29328   15 51 20.08   +26 47 46.1   21.7
           1.29458   15 51 20.02   +26 47 45.6   21.1
           1.30566   15 51 19.30   +26 47 42.0   21.5
           1.30696   15 51 19.22   +26 47 41.7   21.2
           1.31806   15 51 18.51   +26 47 38.2   21.4
           1.31936   15 51 18.44   +26 47 37.9   21.2
           1.50051   15 51 06.88   +26 46 41.4   21.0
           1.50116   15 51 06.82   +26 46 41.1   21.2

Four 45-s Pan-STARRS2 w-band survey images taken on May 6.4 UT in 1".5-1".7
seeing show a condensed head of size 2".2 (FWHM) and mag 20.4-21.1 and no
obvious tail.  Four 45-s Pan-STARRS2 w-band survey images taken on May 29.3 in
1".1 seeing show a condensed head of size 1".7 (FWHM) and mag 21.0-21.1 and no
tail.  Weryk adds that three 60-s gri-band follow-up images obtained on June
2.5 with the 3.6-m Canada-France-Hawaii Telescope on Mauna Kea by R. Wainscoat
and Weryk (queue observer L. Wells; queue coordinator T. Burdullis) in 0".9
seeing show a very condensed head of size 1".3 and a broad tail 8" long
spanning p.a. 50-140 degrees.  Weryk subsequently identified pre-discovery
observations of the comet obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien
reflector at Haleakala on May 1.4 (at mag 21.1), May 2.4 (mag 20.6-20.8), May
4.6 (mag 21.1), May 8.4 (mag 21.9), May 18.5 (mag 21.9), May 21.4 (mag 21.2),
and May 31.5 (mag 19.7).
     Previously unconnected single-night observations of this comet that were
made with the Mt. Lemmon Survey 1.5-m reflector from Apr. 30.4 (mag 20.4-21.7)
and May 14.4 UT (mag 20.8-21.1) were found in the ITF.  The available
astrometry appears on MPEC 2024-L59.  The following elliptical orbital
elements by S. Nakano (Central Bureau) are from 54 observations spanning 2024
Apr. 30-2024 June 5 (mean residual 0".3).  There are no close approaches to
major planets.  The formal error/uncertainty in the period is +/- 34.2 days.

     T = 2025 Apr. 23.27405 TT        Peri. = 171.78284
     e = 0.5302908                    Node  =  45.15753 2000.0
     q = 5.3485541 AU                 Incl. =  99.15183
       a = 11.3869484 AU   n = 0.02565034   P =  38.4 years

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 10.5 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 05 10    16 15.22   +27 58.9    4.945    5.666   131.6     7.7  20.0
2024 05 20    16 04.52   +27 38.0    4.918    5.648   132.2     7.6  20.0
2024 05 30    15 53.76   +26 59.2    4.920    5.632   130.6     7.9  20.0
2024 06 09    15 43.41   +26 02.8    4.948    5.615   126.8     8.3  20.0
2024 06 19    15 33.91   +24 50.6    5.002    5.600   121.4     8.9  20.0
2024 06 29    15 25.56   +23 25.2    5.079    5.584   114.9     9.5  20.0
2024 07 09    15 18.58   +21 49.8    5.175    5.569   107.7    10.0  20.0
2024 07 19    15 13.06   +20 07.4    5.287    5.554   100.0    10.4  20.1
2024 07 29    15 09.02   +18 20.9    5.409    5.540    92.1    10.6  20.1
2024 08 08    15 06.38   +16 32.9    5.538    5.527    84.1    10.5  20.2
2024 08 18    15 05.07   +14 45.3    5.669    5.513    76.0    10.3  20.2
2024 08 28    15 04.93   +12 59.5    5.798    5.501    68.1     9.8  20.2
2024 09 07    15 05.86   +11 16.8    5.920    5.489    60.1     9.2  20.3
2024 09 17    15 07.70   +09 37.9    6.032    5.477    52.4     8.4  20.3
2024 09 27    15 10.33   +08 03.4    6.131    5.465    44.8     7.4  20.3


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

                         (C) Copyright 2024 CBAT
2024 June 6                      (CBET 5402)              Daniel W. E. Green