Electronic Telegram No. 5500
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)
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Prepared using the Tamkin Foundation Computer Network


ANDROMEDID METEOR SHOWER OUTBURST
     P. Jenniskens, SETI Institute and NASA Ames Research Center; A. Howell,
Cameras for Allsky Meteor Surveillance (CAMS) low-light video survey, Florida;
C. Johannink and M. Breukers, CAMS BeNeLux; N. Moskovitz, Lowell Observatory;
and L. Juneau, CAMS Arkansas, report the return of the episodic December
phi-Cassiopeiids (IAU shower 446), a component of the Andromedid meteors from
comet 3D/Biela, during 2024 Nov. 28-Dec. 4 (cf. URL http://cams.seti.org/FDL/)
A total of thirty-one December phi-Cassiopeiids were triangulated by CAMS
BeNeLux, twenty-five by LO-CAMS, twenty-one by CAMS California, fourteen by
CAMS Florida, and six by CAMS Arkansas.  During those days, the shower
activity gradually rose, and peaked at solar longitude 251.08 +/- 0.12 deg
(equinox J2000.0) on Dec. 3, before rapidly declining.  At the peak, meteors
radiated from geocentric radiant R.A. = 20.6 +/- 1.3 deg, Decl. = +55.6 +/-
0.6 deg with geocentric velocity (v_g) 17.3 +/- 1.2 km/s.  A similar outburst
was observed in 2011, and not seen in intermediate years, when it was
centered at R.A. = 20.0 +/- 0.2 deg, Decl. = +57.7 +/- 0.2 deg with v_g = 16.4
+/- 0.2 km/s during the peak at solar longitude 251.88 +/- 0.14 deg (N = 79).


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 February 7                  (CBET 5500)              Daniel W. E. Green