Electronic Telegram No. 5161
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


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, where it was
inadvertently given a provisionally different name), 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 centered on solar longitude 143.16 +/- 0.02 deg (33 orbits), while
the second, stronger peak was centered 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.  The
following CAMS networks contributed to this report:  82 meteors were
triangulated by CAMS Namibia (coordinated by T. Hanke), 11 by CAMS Chile (S.
Heathcote, E. Jehin), 9 by LO-CAMS (N. Moskovitz), 9 by CAMS BeNeLux (C.
Johannink), 7 by CAMS California (station operators T. Beck, J. Albers, E.
Egland, and B. Grigsby), 5 by CAMS Florida (A. Howell), 5 by CAMS South
Africa (T. Cooper), 4 by CAMS Arkansas (L. Juneau), 3 by CAMS Texas (W.
Cooney) and 1 by the UAE Astronomical Camera Network (M. Odeh).


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2022 CBAT
2022 August 26                   (CBET 5161)              Daniel W. E. Green