[Iaude] CBET 4788: COMET C/2020 K6

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4788
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/2020 K6 (RANKIN)
     David Rankin reports his discovery of a comet on CCD images obtained
with the Mount Lemmon Survey's 1.5-m reflector (discovery observations
tabulated below).  Rankin noted a condensed coma about 8" across with a
small tail toward p.a. 90 degrees.

     2020 UT             R.A. (2000) Decl.       Mag.   Observer
     May  26.37175   19 58 37.17   -18 41 31.5   20.5   Rankin
          26.37832   19 58 36.97   -18 41 29.7   20.6     "
          26.38490   19 58 36.76   -18 41 28.4   20.5     "
          26.39146   19 58 36.49   -18 41 27.3   20.0     "

After the comet was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists commented on the object's appearance.  Sixteen stacked 60-s
exposures taken remotely by H. Sato, Tokyo, Japan, with a 0.51-m f/6.8
astrograph at Siding Spring, NSW, on May 26.8 UT show only stellar
appearance; the magnitude was 20.3 as measured within a circular aperture of
radius 4".9.  A. Aletti reports that stacked stacked 30-s exposures obtained
with a 0.36-m f/6 reflector at Varese, Italy, on May 28.04-28.07 show a
diffuse coma 5" wide and of mag 20.0 with no tail.
     The available astrometry appear on MPEC 2020-L03.  The following
very preliminary parabolic orbital elements by S. Nakano (Sumoto, Japan) are
from 27 observations spanning May 26-June 1 (mean residual 0".4).

     T = 2021 Aug. 24.1652 TT         Peri. =  41.4482
                                      Node  = 291.5647  2000.0
     q = 6.000976 AU                  Incl. = 103.7996

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 10.0 and 2.5n = 7.5 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2020 04 21    20 10.01   -20 53.7    6.807    6.897    90.9     8.4  20.5
2020 05 01    20 08.26   -20 15.5    6.601    6.864   100.9     8.3  20.4
2020 05 11    20 05.37   -19 38.1    6.401    6.831   111.2     7.9  20.3
2020 05 21    20 01.29   -19 01.2    6.214    6.799   121.6     7.3  20.2
2020 05 31    19 56.05   -18 24.6    6.043    6.767   132.3     6.4  20.1
2020 06 10    19 49.73   -17 48.3    5.896    6.736   143.1     5.2  20.1
2020 06 20    19 42.46   -17 11.9    5.776    6.705   154.1     3.8  20.0
2020 06 30    19 34.49   -16 35.6    5.688    6.675   164.9     2.3  20.0
2020 07 10    19 26.08   -15 59.2    5.634    6.645   173.4     1.0  19.9
2020 07 20    19 17.58   -15 23.0    5.616    6.616   169.0     1.7  19.9
2020 07 30    19 09.33   -14 47.3    5.632    6.588   158.5     3.2  19.9
2020 08 09    19 01.64   -14 12.4    5.682    6.560   147.5     4.8  19.9
2020 08 19    18 54.77   -13 38.7    5.761    6.532   136.5     6.1  19.9


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

                         (C) Copyright 2020 CBAT
2020 June 1                      (CBET 4788)              Daniel W. E. Green