Electronic Telegram No. 5497
Central Bureau for Astronomical Telegrams
Mailing address: Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network
COMET C/2025 B1 (PANSTARRS)
Y. Ramanjooloo, Institute for Astronomy, University of Hawaii, reports
the discovery of another comet in images taken on Jan. 20 UT with the
Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala (discovery
observations tabulated below). Four stacked 45-s w-band survey images taken
in 1".2-1".3 seeing show a condensed head of size 2".4 (full-width-at-half-
maximum) with a straight tail 7" long in p.a. 220 degrees.
2025 UT R.A. (2000) Decl. Mag.
Jan. 20.24040 5 56 04.37 +16 53 17.8 20.7
20.25124 5 56 04.03 +16 53 24.4 20.6
20.26212 5 56 03.68 +16 53 30.7 20.7
20.27295 5 56 03.33 +16 53 37.3 20.6
20.38375 5 55 59.82 +16 54 42.5 21.5
20.38440 5 55 59.81 +16 54 42.7 20.1
After the comet was posted to the Minor Planet Center's PCCP webpage, S. Deen
(Simi Valley, CA, USA) found archival observations taken with the Mt. Lemmon
Survey's 1.5-m reflector on 2024 Dec. 24.35-24.37 (mag 20.4) and 2025 Jan.
3.28-3.30 UT (mag 20.3). On Dec. 24, the object does not appear obviously
cometary (but a star to the southeast, towards the anti-solar vector, may be
hiding any tail); its nuclear condensation may be slightly less than stellar,
but not confidently so. On Jan. 3, the comet showed a fairly condensed coma
about 3" (FWHM) in size and a 9" tail pointing towards p.a. 230 degrees.
M. Jaeger writes that twenty-nine 90-s CMOS images taken on 2025 Jan.
21.86 UT with a 0.30-m f/4 reflector at Martinsberg, Austria, shows a
possible coma of size 7" of total magnitude 20.0; he notes that the comet's
head appears softer than the images of nearby stars of similar brightness.
The available astrometry appears on MPEC 2025-B77. The following
parabolic orbital elements by S. Nakano (Central Bureau) are from 35
observations spanning 2024 Dec. 24-2025 Jan. 23 (mean residual 0".6); they
indicate that the comet passed 1.74 AU from Jupiter on 2024 Nov. 10 UT.
T = 2025 June 26.19686 TT Peri. = 23.40132
Node = 102.85251 2000.0
q = 3.5313557 AU Incl. = 39.62111
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 12.5 and 2.5n = 8 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2025 01 05 06 05.04 +14 26.3 2.908 3.862 164.0 4.0 19.5
2025 01 10 06 01.88 +15 13.8 2.909 3.844 159.2 5.2 19.5
2025 01 15 05 58.91 +16 02.2 2.918 3.827 154.0 6.5 19.5
2025 01 20 05 56.19 +16 50.9 2.935 3.810 148.6 7.7 19.5
2025 01 25 05 53.80 +17 39.9 2.959 3.793 143.2 8.9 19.5
2025 01 30 05 51.79 +18 28.5 2.989 3.777 137.8 10.1 19.5
2025 02 04 05 50.21 +19 16.8 3.025 3.761 132.5 11.1 19.5
2025 02 09 05 49.09 +20 04.2 3.066 3.746 127.2 12.1 19.5
2025 02 14 05 48.46 +20 50.7 3.112 3.731 122.1 13.0 19.5
2025 02 19 05 48.33 +21 36.2 3.162 3.717 117.0 13.7 19.6
2025 02 24 05 48.71 +22 20.4 3.215 3.703 112.1 14.3 19.6
2025 03 01 05 49.60 +23 03.3 3.272 3.690 107.3 14.9 19.6
2025 03 06 05 51.01 +23 44.9 3.330 3.677 102.6 15.3 19.6
2025 03 11 05 52.91 +24 25.1 3.390 3.664 98.1 15.6 19.7
2025 03 16 05 55.30 +25 03.7 3.452 3.653 93.6 15.8 19.7
2025 03 21 05 58.15 +25 40.9 3.514 3.641 89.3 15.9 19.7
2025 03 26 06 01.46 +26 16.6 3.577 3.630 85.1 15.9 19.7
2025 03 31 06 05.19 +26 50.8 3.639 3.620 81.0 15.8 19.8
2025 04 05 06 09.34 +27 23.4 3.701 3.610 77.0 15.7 19.8
2025 04 10 06 13.88 +27 54.4 3.762 3.601 73.1 15.4 19.8
2025 04 15 06 18.78 +28 23.9 3.822 3.593 69.3 15.1 19.9
2025 04 20 06 24.03 +28 51.7 3.881 3.584 65.6 14.8 19.9
2025 04 25 06 29.60 +29 18.0 3.938 3.577 62.0 14.4 19.9
2025 04 30 06 35.48 +29 42.6 3.993 3.570 58.4 13.9 19.9
2025 05 05 06 41.65 +30 05.7 4.046 3.564 55.0 13.4 19.9
2025 05 10 06 48.09 +30 27.0 4.096 3.558 51.6 12.8 20.0
2025 05 15 06 54.77 +30 46.8 4.144 3.552 48.3 12.3 20.0
2025 05 20 07 01.68 +31 04.9 4.190 3.548 45.0 11.6 20.0
2025 05 25 07 08.81 +31 21.4 4.233 3.544 41.9 11.0 20.0
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2025 CBAT
2025 January 23 (CBET 5497) Daniel W. E. Green