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THE ASTRONOMER Electronic Circular No 3731      2022 Aug 27 14.10UT
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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AUGUST DELTA CAPRICORNIDS METEOR SHOWER 2022

P. Jenniskens, SETI Institute and NASA Ames Research Center, reports that, 
after a strong detection on Aug. 17 (cf. CBET 5159) this new shower was no 
longer detected on Aug. 18 (cf. website URL http://cams.seti.org/FDL/ for the 
date of 2022 Aug 18).  In all, 137 meteors were triangulated by the global 
CAMS networks, concentrated mainly during two brief time intervals.  The first 
peak was centred on solar longitude 143.16 +/- 0.02 deg (33 orbits), while the 
second, stronger peak was centred on solar longitude 143.707 +/- 0.008 deg 
(equinox J2000.0), corresponding to 2022 Aug. 16 at 22h00m UTC (98 orbits).  
Six meteors were detected outside these intervals.  That second outburst was 
predicted.  The parent comet of this meteor shower is now identified as 
45P/Honda-Mrkos-Pajdusakova, with the difference in the orientation of the 
nodal line between current comet orbit and meteor shower mostly a consequence 
of a close encounter of the comet with Jupiter in 1983.The shower previously 
associated with this comet from D-criterion searches among photographed orbits 
is IAU shower number 199, called the August delta Capricornids.  M. Maslov 
predicted an encounter with the 1980 dust of 45P (cf. 
http://feraj.ru/Radiants/Predictions/45p-ids2022eng.html) on 2022 Aug.16 
around 23h40m UTC and put the radiant at R.A. = 326.8 deg, Decl. = -15.1 deg.  
The observed coordinates for the second peak were R.A. = 325.28 +/- 0.06, 
Decl. = -11.40 +/- 0.06 with geocentric velocity 24.12 +/- 0.14 km/s.

The earth passed only 0.0038 AU from the center of the dust trail and 
encountered dust ejected at a modest velocity of 9.8 m/s.  This is the first 
time that an encounter with the dust trails of 45P has been confirmed. 

Guy M Hurst


