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THE ASTRONOMER Electronic Circular No 3727      2022 Aug 19 09.04UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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METEOR SHOWER FROM COMET C/2015 D4 (BORISOV)

P. Jenniskens, SETI Institute and NASA Ames Research Center; and E.
Lyytinen, Helsinki, Finland, provide the following update on expected meteor 
activity from long-period comet C/2015 D4, now that an improved comet orbit is 
available (cf. CBET 4127).  Based on an orbit for C/2015 D4 calculated by G. 
V. Williams from 43 observations spanning 2015 Feb. 23-Oct. 15 (cf. MPEC 2015-
U54), the position of the one-revolution dust trail was calculated for the 
period 1996-2070.  Results show that the dust trail will be in the earth's 
path on 2017 July 29d00h22m UT (solar longitude 125.858 deg), when the earth 
passes the center of the trail at a relative distance of only r - Delta = 
+0.0006 AU; the earth will thus pass inside the comet's orbit at a time when 
the comet has just passed perihelion, both favorable circumstances for 
detecting meteors.  Meteors are expected from geocentric R.A. = 79 deg, Decl. 
= -32 deg, with geocentric velocity 45.9 km/s.

A previous good encounter occurred on 2006 July 29d04h11m UT (r - Delta = 
+0.0003 AU, solar long. = 125.841 deg).  Future encounters are predicted +on 
2029 July 29d01h53m (+0.0007 AU, 125.816 deg), 2042 July 29d10h48m (+0.0006 
AU, 125.886 deg), 2053 July 29d05h35m (+0.0001 AU, 125.848 deg), and on 2068 
July 29d02h09m UT (-0.0001 AU, 125.863 deg).

CBAT

Guy Hurst

