Electronic Telegram No. 5361
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2019 G2 (PANSTARRS)
     An apparently asteroidal object discovered in images obtained with the
Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on 2019 Apr. 2 UT
was given the designation A/2019 G2 when announced on MPEC 2019-H30 (see also
MPEC 2019-Q05) due to its nearly parabolic orbit.  The discovery observations
are tabulated below.

     2019 UT             R.A. (2000) Decl.       Mag.
     Apr.  2.44043   13 29 10.27   - 4 26 38.7   21.3
           2.45326   13 29 08.69   - 4 26 24.6   21.4
           2.46612   13 29 07.09   - 4 26 11.2   21.2

P. Veres, Minor Planet Center, relates that D. Rankin reported on 2020 Jan. 14
that images obtained that date with the 0.7-m Catalina Schmidt telescope
showed a broad 10" tail in p.a. 130 degrees (see MPEC 2024-E1).
     The following reports were sent to the Central Bureau (as well as to the
MPC) several years ago.  CCD exposures taken remotely on 2020 Jan. 19.22 UT by
H. Sato (Tokyo, Japan) using a 0.43-m f/6.8 astrograph located at Mayhill, NM,
USA, show only a stellar appearance; the magnitude was 19.2 as measured in a
circular aperture of radius 5".7.  K. Sarneczky, C. Kalup, and V. Kecskemethy,
Konkoly Observatory, reported in late January 2020 that ten stacked 60-s
unfiltered CCD images taken with the 1.02-m Ritchey-Chretien telescope at
Piszkesteto, Hungary, on 2020 Jan. 24.8 show that this object then showed a
diffuse, 6" coma with a central condensation, and had red magnitude 20.0-20.6.
     S. Deen (Simi Valley, CA, USA) writes that he found a moderately diffuse
coma of size 1".5 (full-width-at-half-maximum) in 0".6 seeing with no apparent
tail in a 90-s i-band 90 DECam exposure obtained on 2019 Feb. 27.35 UT with
the Cerro Tololo 4-m reflector.  A 90-s g-band DECam exposure taken on 2019
Feb. 28.33 shows a diffuse coma of size 1".7 (FWHM) in 0".8 seeing with no
apparent tail.  A 90-s g-band DECam exposure taken on 2019 Mar. 2.34 in 0".9
seeing shows a moderately condensed coma of size 1".1 (FWHM) with no apparent
tail.  A 450-s VR-band DECam image taken on 2019 Apr. 5 shows a moderately
condensed coma of size 1".5 (FWHM) in 1".2 seeing with no apparent tail.  A
115-s r-band image taken on 2019 May 24 with the 8.1-m "Gemini North"
telescope at Mauna Kea shows a condensed coma of size 0".7 (FWHM) in 0".4
seeing and a very broad 3" tail in p.a. 55-130 degrees.  A 120-s r-band
image taken in 0".6 seeing with the Canada-France-Hawaii Telescope (CFHT) on
2019 July 5.28 shows a condensed coma of size 0".7 (FWHM) with a straight 2"
tail at p.a. 90 deg.  A 180-s r-band CFHT image taken on 2019 Dec. 3.6 shows
a condensed coma of size 0".7 (FWHM) in 0".5 seeing with a broad 5" tail at
p.a. 260-300 deg.  A 120-s r-band "Gemini North" taken in 0".5 seeing on
2019 Dec. 28 shows a condensed coma of size 0".7 (FWHM) with a broad 9" tail
in p.a. 255-300 deg.  A 120-s r-band CFHT image taken in 0".5 seeing on 2020
Feb. 26 shows an essentially stellar head with a broad tail at p.a. 90-185
degrees.
     The following orbital elements by S. Nakano (Central Bureau) are from 123
observations spanning 2019 Feb. 27-2020 Sept. 13 (mean residual 0".5), with
corresponding "original" and "future" values of 1/a being +0.002674 and
+0.002397 (+/- 0.000001) AU**-1, respectively.   These indicate that the comet
passed 3.04 AU from Saturn on 2016 Aug. 12 and 0.99 AU from Jupiter on 2018
June 18 UT.

                    Epoch = 2019 Dec. 23.0 TT
     T = 2019 Dec. 10.06239 TT        Peri. =  82.65294
     e = 0.9967948                    Node  = 208.14430 2000.0
     q = 2.2913520 AU                 Incl. = 159.21163

The comet reached a peak brightness near mag 18.5 in late 2019 and early 2020,
and the indicated photometric power-law parameters for this comet are H = 15.0
and 2.5n = 8, but it is now some 13 AU from the sun and no longer observable.


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

                         (C) Copyright 2024 CBAT
2024 March 1                     (CBET 5361)              Daniel W. E. Green