[Iaude] CBET 4777: COMET C/2020 H7

quai at eps.harvard.edu quai at eps.harvard.edu
Thu May 21 18:56:45 EDT 2020


                                                  Electronic Telegram No. 4777
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 H7 (LEMMON)
     An apparently asteroidal object discovered on images taken by G. J.
Leonard with the Mount Lemmon Survey 1.5-m reflector on Apr. 29.4 UT
(discovery observations tabulated below) has been found to show cometary
appearance by observers elsewhere after the object was posted on the Minor
Planet Center's PCCP webpage.

     2020 UT             R.A. (2000) Decl.       Mag.   Observer
     Apr. 29.42332   17 40 11.31   +27 32 32.7   20.6   Leonard
          29.42852   17 40 10.87   +27 32 36.9   20.7     "
          29.43376   17 40 10.38   +27 32 40.7   20.7     "
          29.43900   17 40 09.92   +27 32 44.9   20.6     "
          29.47407   17 40 06.79   +27 33 12.2   20.6     "
          29.47764   17 40 06.48   +27 33 14.9            "
          29.47919   17 40 06.33   +27 33 15.5            "

H. Sato, Tokyo, Japan, writes that fourteen stacked 60-s exposures taken
remotely with a 0.61-m f/6.5 astrograph located at the Sierra Remote
Observatory near Auberry, CA, USA, on May 2.5 UT show a stellar appearance;
the magnitude was 20.8 as measured within a circular aperture of radius 3".7.
Twenty-five stacked 120-s unfiltered exposures taken by E. Bryssinck,
Kruibeke, Belgium, with a 0.4-m f/3.8 reflector, during May 11.94-11.97 shows
a diffuse, elongated coma of size 8" x 11", oriented north-south (p.a. about
183 deg); the magnitude was 20.0 in an aperture of radius 5".  Images taken
by D. D. Balam and D. W. E. Green on May 18.34 with the 1.82-m Plaskett
telescope (+ SDSS g' filter) of the National Research Council of Canada show
a small coma (full-width-at-half-maximum 4".2, vs. 2".5 for nearby stars)
that is elongated toward p.a. about 100 degrees; additional exposures taken
on May 19.3 show the comet to be clearly extended compared to nearby stars.
     The available astrometry appear on MPEC 2020-K107.  The following
preliminary parabolic orbital elements by S. Nakano, Sumoto, Japan, are from
130 observations spanning Apr. 29-May 19 (mean residual 0".4).

     T = 2020 June  2.8617 TT         Peri. =  82.6623
                                      Node  = 323.5151  2000.0
     q = 4.420622 AU                  Incl. = 135.9203

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 11.5 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2020 04 21    17 51.58   +25 38.4    3.967    4.435   111.5    12.2  19.7
2020 04 26    17 45.05   +26 47.0    3.912    4.431   114.9    11.9  19.6
2020 05 01    17 37.84   +27 53.0    3.865    4.429   118.1    11.6  19.6
2020 05 06    17 29.98   +28 55.5    3.825    4.427   120.8    11.3  19.6
2020 05 11    17 21.52   +29 53.3    3.793    4.425   123.0    11.0  19.6
2020 05 16    17 12.51   +30 45.5    3.770    4.423   124.6    10.8  19.5
2020 05 21    17 03.05   +31 31.0    3.756    4.422   125.6    10.7  19.5
2020 05 26    16 53.25   +32 09.1    3.751    4.421   125.8    10.7  19.5
2020 05 31    16 43.25   +32 39.0    3.756    4.421   125.4    10.8  19.5
2020 06 05    16 33.18   +33 00.6    3.769    4.421   124.3    10.9  19.5
2020 06 10    16 23.17   +33 13.7    3.792    4.421   122.5    11.2  19.6
2020 06 15    16 13.38   +33 18.4    3.823    4.422   120.2    11.5  19.6
2020 06 20    16 03.91   +33 15.3    3.862    4.423   117.4    11.8  19.6
2020 06 25    15 54.89   +33 04.8    3.908    4.424   114.3    12.1  19.6
2020 06 30    15 46.40   +32 47.8    3.961    4.426   110.9    12.4  19.7
2020 07 05    15 38.51   +32 25.0    4.020    4.428   107.2    12.7  19.7
2020 07 10    15 31.25   +31 57.5    4.084    4.431   103.4    12.9  19.7


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

                         (C) Copyright 2020 CBAT
2020 May 21                      (CBET 4777)              Daniel W. E. Green



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