[Iaude] CBET 4807: COMET P/2020 M2 =P/2012 SB6
quai at eps.harvard.edu
quai at eps.harvard.edu
Tue Jun 30 21:00:02 EDT 2020
Electronic Telegram No. 4807
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 P/2020 M2 = P/2012 SB_6 (LEMMON)
H. Sato, Tokyo, Japan, reports his recovery of comet P/2012 SB_6 (cf.
CBET 3251) on CCD images obtained remotely with a 0.51-m f/6.8 astrograph at
Siding Spring, NSW, Australia, on June 29.8 UT (six stacked 60-s exposures),
and with a 0.43-m f/6.8 astrograph near Mayhill, NM, USA, on June 30.44
(fourteen stacked 60-s exposures). The comet showed a strongly condensed
coma 12" in diameter on both nights; on the second night only, there was a
hint of a fan-like tail 10" long toward the west. The total magnitudes
tabulated in the astrometry below were measured within circular apertures of
radii 6".6 and 7".6 on June 29 and 30, respectively.
2020 UT R.A. (2000) Decl. Mag. Observer
June 29.82484 2 52 33.97 +19 24 15.6 Sato
29.82758 2 52 34.24 +19 24 17.9 17.8 "
30.43562 2 53 41.89 +19 31 19.6 "
30.43954 2 53 42.33 +19 31 22.2 "
30.44347 2 53 42.74 +19 31 25.1 17.6 "
The corresponding residuals are +116" in R.A. and +59" in Decl. with respect
to the prediction by S. Nakano in NK 2419 and in the ICQ 2019 and 2020 Comet
Handbooks; the indicated correction is Delta(T) = -0.14 day. The following
linked orbital elements by Nakano are from 195 observations spanning
2012-2020 (mean residual 0".6), and they indicate that the comet passed 0.14
AU from Jupiter in 1928 September, just before its 1928 perihelion; prior to
that close approach, the orbit had q = 4.58 AU and e = 0.20.
Epoch = 2012 Nov. 9.0 TT
T = 2012 Oct. 31.96983 TT Peri. = 12.78611
e = 0.3846227 Node = 9.55707 2000.0
q = 2.4064476 AU Incl. = 10.98961
a = 3.9105237 AU n = 0.12745348 P = 7.73 years
Epoch = 2020 May 31.0 TT
T = 2020 June 19.24492 TT Peri. = 14.38703
e = 0.4047543 Node = 8.21117 2000.0
q = 2.2768653 AU Incl. = 10.92881
a = 3.8250847 AU n = 0.13174753 P = 7.48 years
Epoch = 2027 Dec. 21.0 TT
T = 2027 Dec. 21.34170 TT Peri. = 14.57900
e = 0.4040420 Node = 8.14101 2000.0
q = 2.2844346 AU Incl. = 10.91709
a = 3.8332138 AU n = 0.13132866 P = 7.50 years
Epoch = 2035 June 2.0 TT
T = 2035 June 17.04789 TT Peri. = 14.38278
e = 0.4048499 Node = 8.15733 2000.0
q = 2.2812501 AU Incl. = 10.91894
a = 3.8330667 AU n = 0.13133622 P = 7.50 years
The current brightness reported by Sato is about 1.5 mag brighter than
would be predicted from the 2012 apparition, but the ephemeris below (by the
undersigned from the above elements) uses photometric power-law parameters
H = 11.5 and 2.5n = 15 from the previous return under the assumption that the
comet is currently in outburst. Photometric monitoring throughout the
current apparition is encouraged.
Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
2020 06 20 02 34.28 +17 26.4 2.842 2.277 47.2 19.1 19.1
2020 06 25 02 43.60 +18 27.1 2.802 2.277 49.5 19.9 19.1
2020 06 30 02 52.89 +19 26.3 2.760 2.278 51.9 20.6 19.1
2020 07 05 03 02.13 +20 23.8 2.718 2.280 54.3 21.2 19.0
2020 07 10 03 11.31 +21 19.7 2.674 2.282 56.8 21.9 19.0
2020 07 15 03 20.42 +22 13.9 2.630 2.284 59.3 22.5 19.0
2020 07 20 03 29.44 +23 06.5 2.585 2.288 61.8 23.0 19.0
2020 07 25 03 38.34 +23 57.4 2.539 2.292 64.4 23.6 18.9
2020 07 30 03 47.11 +24 46.7 2.493 2.296 67.1 24.0 18.9
2020 08 04 03 55.71 +25 34.3 2.446 2.301 69.8 24.4 18.9
2020 08 09 04 04.12 +26 20.5 2.398 2.306 72.5 24.8 18.8
2020 08 14 04 12.32 +27 05.2 2.350 2.312 75.4 25.1 18.8
2020 08 19 04 20.26 +27 48.5 2.301 2.319 78.3 25.3 18.8
2020 08 24 04 27.91 +28 30.6 2.253 2.326 81.3 25.5 18.8
2020 08 29 04 35.22 +29 11.5 2.204 2.333 84.4 25.5 18.7
2020 09 03 04 42.17 +29 51.4 2.155 2.341 87.6 25.5 18.7
2020 09 08 04 48.70 +30 30.4 2.106 2.350 91.0 25.4 18.7
2020 09 13 04 54.76 +31 08.8 2.058 2.359 94.4 25.2 18.7
2020 09 18 05 00.31 +31 46.5 2.010 2.369 98.0 24.8 18.6
2020 09 23 05 05.27 +32 23.8 1.963 2.379 101.7 24.4 18.6
2020 09 28 05 09.61 +33 00.6 1.917 2.389 105.5 23.8 18.6
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2020 CBAT
2020 June 30 (CBET 4807) Daniel W. E. Green
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