[Iaude] CBET 4662: COMET P/2007 T4

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4662
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)
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Prepared using the Tamkin Foundation Computer Network


COMET P/2007 T4 (GIBBS)
     H. Sato, Tokyo, Japan, reports his recovery of comet P/2007 T4 (cf. IAUCs
8880, 8897) on stacked CCD exposures taken on Sept. 5.48 UT with a 0.43-m
f/6.8 astrograph near Mayhill, NM, USA.  Sato noted the comet to be strongly
condensed with a coma 10" in diameter and a faint, fan-like tail 20" long
toward p.a. 280-340 degrees; the magnitude was 18.7 as measured within a
circular aperture of radius 5".7.  Confirming CCD 40-s unfiltered exposures
were obtained by T. Chen and D. W. E. Green with a 0.3-m f/7.2 reflector at
Ngari, Tibet, China, in the course of the BIST survey (cf. CBET 4629).
Sixteen stacked BIST exposures taken on Sept. 6.94 show an uncondensed coma
of size about 6" (in 3" seeing), with a possible elongation toward the
southeast/northwest; the comet very faint even in stacked images.  Twenty-five
stacked BIST exposures on Sept. 7.95 show an uncondensed coma of size about
6" apparently elongated along p.a. about 320/140 degrees; the total unfiltered
magnitude was 19.6-19.7 in a 8"-diameter photometric aperture.  The astrometry
are tabulated below.

     2019 UT             R.A. (2000) Decl.       Mag.   Observer
     Sept. 5.47589    8 16 11.30   +36 25 24.9          Sato
           5.47860    8 16 11.74   +36 25 24.8            "
           5.48130    8 16 12.23   +36 25 24.9   18.7     "
           6.93756    8 20 20.34   +36 23 30.0   19.6   Chen
           6.94298    8 20 21.15   +36 23 30.2   19.3     "
           7.95043    8 23 12.25   +36 22 00.5   19.7     "
           7.95254    8 23 12.61   +36 21 59.7   19.6     "

The indicated correction to the prediction by S. Nakano in the ICQ's 2019
Comet Handbook (and NK 1629) is Delta(T) = -0.02 day.  The following linked
orbital elements by Nakano are from 71 observations spanning 2007-2019 (mean
residual 0".69).  Nakano adds that he was unable to find any additional past
observations of this comet in archival data.

                    Epoch = 2007 Aug.  8.0 TT
     T = 2007 July 20.72527 TT        Peri. =  42.51823
     e = 0.6174233                    Node  =  37.22920 2000.0
     q = 2.0088331 AU                 Incl. =  23.87178
       a =  5.2507979 AU   n = 0.08191551   P =  12.03 years

                    Epoch = 2019 July 16.0 TT
     T = 2019 July 23.63555 TT        Peri. =  42.42372
     e = 0.6180854                    Node  =  37.05890 2000.0
     q = 2.0050202 AU                 Incl. =  23.85877
       a =  5.2499172 AU   n = 0.08193612   P =  12.03 years

                    Epoch = 2031 Aug.  2.0 TT
     T = 2031 July 28.83942 TT        Peri. =  42.32795
     e = 0.6181856                    Node  =  36.91351 2000.0
     q = 2.0058077 AU                 Incl. =  23.84282
       a =  5.2533582 AU   n = 0.08185563   P =  12.04 years


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

                         (C) Copyright 2019 CBAT
2019 September 8                 (CBET 4662)              Daniel W. E. Green