[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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