[Iaude] CBET 4823: COMET P/2020 O3

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4823
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 F3 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii, reports the
discovery of another diffuse comet in three 45-s w-band images obtained with
the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on July 28;
in seeng of 1".4, the comet's head showed a full-width-at-half-maximum (FWHM)
of about 2", but there was an obvious straight tail at least 12" long towards
p.a. 240 degrees.  Weryk also identified four 45-s pre-discovery w-band
images taken on July 20 with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector
at Haleakala, when the image quality was poor and the comet appeared quite
diffuse (the head having FWHM size of about 2".5 in 1".7 seeing) with an
obvious straight tail at least 6" long in p.a. 245 degrees.  The discovery
and pre-discovery observations are tabulated below.

     2020 UT             R.A. (2000) Decl.       Mag.
     July 20.48026   22 05 20.07   - 2 06 32.3   20.8
          20.49182   22 05 19.83   - 2 06 32.0   21.0
          20.50337   22 05 19.55   - 2 06 32.0   20.8
          20.51495   22 05 19.23   - 2 06 32.1   21.1
          28.50525   22 01 53.74   - 2 09 13.4   21.0
          28.51861   22 01 53.36   - 2 09 13.9   21.5
          28.53189   22 01 52.94   - 2 09 14.8   20.7
          28.54516   22 01 52.57   - 2 09 15.2   21.2

Y. Ramanjooloo, Institute for Astronomy, reports that four additional 60-s
Pan-STARRS1 w-band images taken on July 29.5 show an obvious tail at least
7".5 long towards p.a. 270 degrees; the comet's very condensed head had FWHM
size of about 2".2 in 1".1 seeing.  Weryk adds that four additional 60-s
Pan-STARRS1 w-band images taken on July 30.5 show a straight tail about 16"
long toward p.a. 240 deg; the comet's condensed head had a FWHM size of 1".6
in 1".2 seeing.
     The available astrometry appears on MPEC 2020-P11.  The following very
preliminary parabolic orbital elements by S. Nakano are from 26 observations
spanning July 20-31 (mean residual 0".3).  A search by Nakano in archival
astrometry produced nothing.

     T = 2020 Dec. 22.4944 TT         Peri. =  76.7217
     e = 0.105548                     Node  = 266.9403  2000.0
     q = 4.177170 AU                  Incl. =   8.4462
       a =  4.670091 AU    n = 0.0976599    P =  10.09 years

The following ephemeris by the undersigned from the above orbital elements
uses photometry power-law parameters H = 12.0 and 2.5n = 10 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2020 07 10    22 08.70   -02 12.1    3.432    4.201   133.9    10.0  20.9
2020 07 20    22 05.52   -02 06.5    3.335    4.199   143.8     8.2  20.8
2020 07 30    22 01.19   -02 10.4    3.261    4.196   153.8     6.1  20.8
2020 08 09    21 56.01   -02 22.8    3.212    4.193   163.3     4.0  20.8
2020 08 19    21 50.38   -02 42.5    3.191    4.191   169.9     2.4  20.7
2020 08 29    21 44.75   -03 07.7    3.199    4.189   167.0     3.1  20.7
2020 09 08    21 39.60   -03 35.6    3.235    4.187   158.2     5.1  20.8
2020 09 18    21 35.32   -04 03.9    3.298    4.185   148.2     7.3  20.8
2020 09 28    21 32.27   -04 30.1    3.385    4.184   138.0     9.2  20.9
2020 10 08    21 30.65   -04 52.0    3.493    4.182   127.9    10.9  20.9
2020 10 18    21 30.56   -05 08.3    3.618    4.181   118.1    12.1  21.0
2020 10 28    21 32.03   -05 17.8    3.755    4.180   108.6    13.0  21.1
2020 11 07    21 34.98   -05 19.9    3.901    4.179    99.4    13.5  21.2


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

                         (C) Copyright 2020 CBAT
2020 August 2                    (CBET 4823)              Daniel W. E. Green