[Iaude] CBET 5321: COMET C/2023 RN_3
quai at eps.harvard.edu
quai at eps.harvard.edu
Tue Dec 5 23:17:19 EST 2023
Electronic Telegram No. 5321
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 RN_3 (ATLAS)
An apparently asteroidal object discovered on CCD images taken on Sept.
4.6 UT with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, 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 and were published under the
minor-planet designation 2023 RN_3 on MPEC 2023-R115.
2023 UT R.A. (2000) Decl. Mag.
Sept. 4.56281 0 10 10.03 + 7 13 13.3 17.5
4.56800 0 10 09.90 + 7 13 13.9 17.3
4.57162 0 10 09.82 + 7 13 12.9 17.7
4.60420 0 10 09.17 + 7 13 07.8 17.9
H. Hsieh, Planetary Science Institute, on behalf of the Las Cumbres
Observatory (LCO) "Outbursting Objects Key Project", reports that three 245-s
observations taken in each of bands r', g', and w' with the LCO 1-m telescope
at Teide Observatory in Tenerife (Canary Islands, Spain) show that 2023 RN_3
is clearly active, with an elliptical coma centered on the nuclear
condensation having its major axis oriented toward p.a. 155 degrees and with
no clearly defined tail. The coma has a size of 3".0 and 2".6 (full-width-at-
half-maximum) in the major and minor axis directions, respectively, in 1".8
seeing; the object's total magnitudes were measured to be g = 18.7 and r =
18.1 on 2023 Nov. 16. An image can be seen at URL https://shorturl.at/noPQ9.
K. Ly, University of California at Los Angeles, writes that 2023 RN_3 is
not visible in archival Cerro Tololo DECam images taken with the 4-m reflector
or in MegaCam images obtained with the Canada-France-Hawaii Telescope in 2016.
Three-hundred-second MegaCam GRI-band exposures show nothing at the predicted
position to limiting mag 23.5 on 2016 May 2, 7, 28, and 29, June 27, and July
7. DECam images of exposure length 150-190 s show nothing at the predicted
position to limiting VR-band mag 23 on 2016 Mar. 6, July 21, and July 22. Ly
further reports that three 600-s unfiltered exposures taken remotely on 2023
Dec. 3.1 UT with a 0.43-m telescope of the "Deep Random Survey" located at Rio
Hurtado, Chile, each shows the comet with a very condensed coma with size 3"
(FWHM) in 2' seeing; co-adding the three exposures reveals that the coma has a
diffuse extension at least 8" in diameter with no tail (V magnitude 18.5).
Seven co-added additional 600-s exposures taken with the same 0.43-m reflector
on Dec. 4.1 by Ly show a slightly elongated and condensed coma of size 7" x
8", with the long axis pointing toward p.a. 320-325 degrees; the V-band
apparent magnitude was 18.2, and no tail was visible.
P. VanWylen, Memphis, TN, USA, writes that he found apparently stellar
pre-discovery images of this object in CCD exposures obtained with the 1.2-m
Schmidt telescope at Palomar in the course of the "Zwicky Transient Facility"
(ZTF) survey on 2023 Aug. 26.4 UT (magnitudes g = 20.3, r = 19.5), Aug.
28.42-28.46 (g = 19.0, r = 18.5), and Aug. 30.40-30.46 (g = 18.7, r = 18.1).
Six stacked 120-s CCD exposures taken remotely by H. Sato (Bunkyo-ku,
Tokyo, Japan) on Oct. 4.2 UT with a "Deep Sky Chile" 0.51-m f/6.8 astrograph
located at Rio Hurtado show 2023 RN_3 to have a strongly condensed coma 10" in
diameter with no tail; the magnitude was 17.1 as measured within a circular
aperture of radius 5".0.
R. Weryk, Department of Physics and Astronomy, University of Western
Ontario, notes that four 45-s w-band survey images obtained with the
Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Nov. 16.3 UT
show a very condensed coma of size 2".2 (full-width-at-half-maximum)
in 1".4 seeing with no tail. Eight further 45-s i-band survey images
taken on Nov. 25 also show this to be clearly an active object, with
a very condensed coma of size 2".0 (FWHM) in 1".1 seeing.
Additional astrometry appears on MPEC 2023-X85. The following orbital
elements by S. Nakano (Central Bureau) are from 488 observations spanning 2023
Aug. 26-2023 Dec. 4 (mean residual 0".3).
Epoch = 2023 Jan. 16.0 TT
T = 2023 Jan. 16.52639 TT Peri. = 130.14733
e = 0.4889006 Node = 207.07684 2000.0
q = 5.1712707 AU Incl. = 10.35616
a = 10.1179356 AU n = 0.03062430 P = 32.18 years
Epoch = 2055 Feb. 17.0 TT
T = 2055 Mar. 8.55740 TT Peri. = 130.08268
e = 0.4916171 Node = 206.87715 2000.0
q = 5.1734219 AU Incl. = 10.36203
a = 10.1762320 AU n = 0.03036152 P = 32.46 years
The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 8.5 and 2.5n = 8 for the
magnitudes.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2023 10 23 23 53.67 +04 21.7 4.483 5.375 151.0 5.2 17.6
2023 11 02 23 51.65 +03 50.3 4.587 5.389 140.4 6.7 17.7
2023 11 12 23 50.60 +03 24.7 4.713 5.404 130.1 8.1 17.7
2023 11 22 23 50.63 +03 06.1 4.859 5.419 119.9 9.1 17.8
2023 12 02 23 51.77 +02 55.1 5.018 5.435 110.0 9.8 17.9
2023 12 12 23 54.00 +02 51.9 5.187 5.451 100.4 10.2 18.0
2023 12 22 23 57.26 +02 56.3 5.361 5.468 91.0 10.4 18.0
2024 01 01 00 01.47 +03 07.9 5.536 5.484 81.9 10.2 18.1
2024 01 11 00 06.52 +03 26.0 5.709 5.502 73.0 9.8 18.2
2024 01 21 00 12.33 +03 49.9 5.875 5.519 64.3 9.2 18.3
2024 01 31 00 18.78 +04 18.8 6.031 5.537 55.8 8.5 18.3
2024 02 10 00 25.76 +04 51.9 6.175 5.556 47.5 7.5 18.4
2024 02 20 00 33.20 +05 28.5 6.304 5.575 39.3 6.5 18.5
2024 06 19 02 07.83 +13 04.7 6.371 5.826 53.6 8.1 18.6
2024 06 29 02 13.89 +13 27.7 6.264 5.849 61.6 8.8 18.6
2024 07 09 02 19.28 +13 46.5 6.145 5.873 69.8 9.4 18.6
2024 07 19 02 23.91 +14 00.5 6.019 5.896 78.2 9.7 18.6
2024 07 29 02 27.70 +14 09.7 5.888 5.920 86.9 9.9 18.5
2024 08 08 02 30.55 +14 13.8 5.756 5.944 95.8 9.8 18.5
2024 08 18 02 32.40 +14 12.4 5.627 5.968 104.9 9.4 18.5
2024 08 28 02 33.21 +14 05.6 5.504 5.993 114.4 8.8 18.4
2024 09 07 02 32.96 +13 53.4 5.393 6.017 124.2 8.0 18.4
2024 09 17 02 31.68 +13 36.0 5.297 6.042 134.3 6.8 18.4
2024 09 27 02 29.47 +13 14.1 5.222 6.068 144.7 5.5 18.4
2024 10 07 02 26.47 +12 48.3 5.170 6.093 155.4 3.9 18.3
2024 10 17 02 22.90 +12 19.8 5.146 6.119 166.2 2.2 18.4
2024 10 27 02 19.02 +11 50.1 5.152 6.145 176.7 0.5 18.4
2024 11 06 02 15.11 +11 20.7 5.189 6.171 171.4 1.4 18.4
2024 11 16 02 11.45 +10 53.4 5.256 6.197 160.5 3.1 18.4
2024 11 26 02 08.31 +10 29.5 5.352 6.223 149.6 4.6 18.5
2024 12 06 02 05.90 +10 10.4 5.475 6.250 138.8 6.0 18.6
2024 12 16 02 04.38 +09 56.9 5.620 6.277 128.2 7.1 18.6
2024 12 26 02 03.82 +09 49.3 5.784 6.303 117.9 7.9 18.7
2025 01 05 02 04.27 +09 47.8 5.961 6.331 107.8 8.5 18.8
2025 01 15 02 05.73 +09 52.2 6.147 6.358 98.0 8.8 18.9
2025 01 25 02 08.13 +10 01.9 6.336 6.385 88.4 8.9 19.0
2025 02 04 02 11.41 +10 16.3 6.526 6.413 79.1 8.7 19.0
2025 02 14 02 15.50 +10 34.7 6.710 6.440 70.0 8.3 19.1
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2023 CBAT
2023 December 6 (CBET 5321) Daniel W. E. Green
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