[Iaude] CBET 4790: COMET C/2020 K7

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4790
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 K7 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii, reports the
discovery of another comet in four 45-s w-band CCD images obtained with the
Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery
observations tabulated below); there is a very condensed coma of diameter
1".7 (in 1".0 seeing) with a broad 6" tail spanning p.a. 245-315 degrees.

     2020 UT             R.A. (2000) Decl.       Mag.
     May  30.54805   20 30 08.25   - 9 22 17.4   20.2
          30.56223   20 30 08.15   - 9 22 14.0   20.3
          30.57644   20 30 08.06   - 9 22 11.1   20.1
          30.59060   20 30 07.96   - 9 22 07.7   20.3

After the object was posted on the Minor Planet Center's PCCP, other CCD
astrometrists have commented on the cometary appearance.  H. Sato, Tokyo,
Japan, found a strongly condensed, round coma 8" in diameter with no tail
on seven stacked 120-s exposures taken remotely with a 0.43-m f/6.8
astrograph located near Mayhill, NM, USA, on May 31.4 UT; the magnitude was
19.3 as measured within a circular aperture of radius 5".7.  E. Guido,
Castellammare di Stabia, Italy, writes that eight stacked 180-s unfiltered
exposures obtained remotely by M. Rocchetto, E. Bryssinck, M. Fulle, G.
Milani, C. Nassef, G. Savini, and himself with a "Telescope Live" 0.6-m f/6.5
astrograph at El Sauce, Chile, on June 2.3 show a compact coma about 6" in
diameter and of mag 19.2-19.3, with a tail 3" long in p.a. 306 deg.
     The available astrometry appear on MPEC 2020-L09.  The following very
preliminary parabolic orbital elements by the undersigned are from 24
observations spanning May 30-June 2.

     T = 2021 Oct.  2.7414 TT         Peri. =  60.2281
                                      Node  = 287.5599  2000.0
     q = 5.682710 AU                  Incl. =  34.6904

The following ephemeris by the undersigned from the above elements uses
photometric power-law parameters H = 9.0 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2020 04 21    20 27.00   -12 05.4    6.827    6.814    85.0     8.4  19.8
2020 05 01    20 29.14   -11 21.9    6.631    6.776    94.0     8.5  19.8
2020 05 11    20 30.40   -10 39.6    6.438    6.739   103.1     8.4  19.7
2020 05 21    20 30.72   -09 59.0    6.251    6.702   112.3     8.0  19.6
2020 05 31    20 30.09   -09 20.6    6.076    6.665   121.7     7.4  19.5
2020 06 10    20 28.53   -08 44.9    5.916    6.629   131.2     6.6  19.4
2020 06 20    20 26.11   -08 12.2    5.775    6.594   140.8     5.6  19.4
2020 06 30    20 22.92   -07 43.0    5.657    6.559   150.2     4.4  19.3
2020 07 10    20 19.14   -07 17.5    5.565    6.524   159.0     3.2  19.2
2020 07 20    20 14.96   -06 55.8    5.501    6.490   165.7     2.2  19.2
2020 07 30    20 10.62   -06 37.9    5.466    6.457   166.4     2.1  19.2
2020 08 09    20 06.40   -06 23.3    5.460    6.424   160.5     3.0  19.1
2020 08 19    20 02.54   -06 11.8    5.482    6.392   151.8     4.3  19.1


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

                         (C) Copyright 2020 CBAT
2020 June 2                      (CBET 4790)              Daniel W. E. Green