[Iaude] CBET 4779: COMET C/2020 K1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4779
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 K1 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii, reports the
discovery of another comet in CCD images obtained with the Pan-STARRS2 1.8-m
Ritchey-Chretien reflector at Haleakala on May 17, with additional
pre-discovery observations made with the same telescope that werre then
identified during the previous month (all astrometry tabulated below).
>From four 45-s w-band exposures taken on Apr. 17, Weryk noted a condensed
coma of diameter 0".5 (full-width-at-half-maximum of 2".5 in 2".0 seeing)
with no tail.  Similar exposurs on Apr. 27 showed a 0".9 condensed coma (FWHM
2".6 in 1".7 seeing) and no tail.  Four 45-s i-band exposures taken on May 6
show a condensed 0".6 coma (FWHM 1".9 in 1".3 seeing) with no tail.  Four
45-s w-band discovery observations on May 17 show a condensed 0".7 coma
(FWHM 2".1 in 1".5 seeing) with no tail.

     2020 UT             R.A. (2000) Decl.       Mag.
     Apr. 17.55119   18 42 42.44   +56 19 12.6   20.4
          17.56480   18 42 42.28   +56 19 16.2   20.5
          17.57844   18 42 42.09   +56 19 19.7   20.1
          17.59207   18 42 41.93   +56 19 23.0   20.2
          27.55593   18 40 02.57   +56 59 54.5   20.2
          27.56963   18 40 02.28   +56 59 57.7   20.1
          27.58329   18 40 02.03   +57 00 01.1   20.1
          27.59699   18 40 01.73   +57 00 04.1   20.3
     May   6.51833   18 36 32.64   +57 32 32.0   20.0
           6.53143   18 36 32.26   +57 32 34.7   21.0
           6.54453   18 36 31.87   +57 32 37.4   20.3
           6.55761   18 36 31.53   +57 32 39.8   20.3
          17.51229   18 30 53.00   +58 05 26.4   20.6
          17.52592   18 30 52.52   +58 05 28.5   20.4
          17.53956   18 30 52.03   +58 05 30.6   20.1
          17.55319   18 30 51.56   +58 05 32.8   20.4

Weryk and R. Wainscoat obtained three 60-s gri-band follow-up observations on
May 19.60 UT with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea
(observers Wainscoat, C. Crowder, and T. Burdullis) that show the object to
be clearly a comet (size FWHM 1".45 in 0".65 seeing) of mag 20.1-20.2; the
comet appears slightly asymmetric, indicating a short tail with a length of
at most about 2" towards the northeast.
     After the comet was posted on the Minor Planet Center's PCCP webpage,
A. Aletti and L. Buzzi report that stacks of 30-s CCD exposures taken on May
19.94-20.06 with a 0.36-m f/6 Schmidt-Cassegrain reflector at Varese, Italy,
show a 5" coma with no elongation or tail visible; they measured the red
magnitude as 19.8.
     The available astrometry appear on MPEC 2020-K111.  The following
preliminary parabolic orbital elements by S. Nakano, Sumoto, Japan, are from
76 observations spanning Apr. 17-May 21 (mean residual 0".3).

     T = 2023 May   8.6839 TT         Peri. = 213.8786
                                      Node  =  94.4049  2000.0
     q = 3.078872 AU                  Incl. =  89.6421

The following ephemeris by the undersigned, from the above orbital elements,
uses photometric power-law parameters H = 7.0 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2020 03 12    18 41.83   +53 42.6   10.010    9.922    82.1     5.7  20.0
2020 03 22    18 43.60   +54 23.9    9.912    9.858    84.0     5.8  19.9
2020 04 01    18 44.27   +55 07.2    9.813    9.794    86.0     5.8  19.9
2020 04 11    18 43.74   +55 51.1    9.713    9.729    88.0     5.9  19.8
2020 04 21    18 41.94   +56 33.6    9.613    9.665    90.0     6.0  19.8
2020 05 01    18 38.82   +57 13.0    9.514    9.600    91.9     6.0  19.8
2020 05 11    18 34.41   +57 47.0    9.418    9.535    93.6     6.1  19.7
2020 05 21    18 28.79   +58 13.8    9.326    9.470    95.1     6.1  19.7
2020 05 31    18 22.13   +58 31.5    9.238    9.405    96.4     6.1  19.6
2020 06 10    18 14.68   +58 38.3    9.156    9.340    97.4     6.2  19.6
2020 06 20    18 06.75   +58 33.2    9.079    9.275    98.0     6.2  19.5
2020 06 30    17 58.71   +58 15.2    9.010    9.210    98.2     6.3  19.5
2020 07 10    17 50.95   +57 44.5    8.947    9.144    98.0     6.3  19.4


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

                         (C) Copyright 2020 CBAT
2020 May 22                      (CBET 4779)              Daniel W. E. Green