Electronic Telegram No. 5736
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


SEPTEMBER EPSILON PERSEID METEOR OUTBURST 2026
     D. Vida and P. Brown, University of Western Ontario; and W. J. Cooke,
NASA Meteoroid Environment Office, report an outburst of the September
epsilon Perseid meteor shower (IAU abbreviation SPE, IAU shower number 208)
as observed by the Global Meteor Network (GMN) low-light video cameras (cf.
website URL https://globalmeteornetwork.org/flux).  The outburst peaked at a
zenithal hourly rate (ZHR) of 9.4 +/- 0.4 meteors/hr at solar longitude 167.21 
+/- 0.08 deg (equinox J2000.0), corresponding to 2026 Sept. 10d06h33m UT +/- 
2 hours.  The ZHR was computed assuming a population index of r = 2.0
(differential mass index s = 1.75), the value adopted for the annual shower;
the population index of the outburst itself has not yet been measured.  The
peak value is based on 998 shower meteors recorded in a single 4.1-hour flux
bin (Sept. 10d04h29m-10d08h37m UT) with a time-area product of 5.3 x 10**5
km**2 hr, corresponding to a flux of 1.88 (95-percent confidence interval
1.74-2.02) meteoroids per 1000 km**2 per hour at a limiting magnitude of +6.5
(limiting mass 1.6 x 10**-8 kg).
     In the six years for which GMN flux measurements of this shower exist
(2020-2025), the SPE peak ZHR ranged from 3.6 to 5.1 meteors/hr, with a mean
of 4.5 +/- 0.1.  The 2026 peak is 2.09 +/- 0.10 times that mean, and the
95-percent confidence intervals do not overlap.  The enhancement is confined
to the single flux bin quoted above:  the preceding bin, centered on solar
longitude 167.04 deg, gives ZHR = 4.9 +/- 0.2, and the following bin,
centered on 167.37 deg, gives ZHR = 5.2 +/- 0.3, both consistent with normal
annual activity.  The duration of the outburst was therefore shorter than the
4.1-hour bin, and the quoted peak ZHR is a lower limit to the true peak.
     The 2026 peak occurred at essentially the same solar longitude as the
2013 SPE outburst, for which Lyytinen calculated an encounter with the
one-revolution dust trail of a long-period comet at solar longitude 167.200
deg (cf. CBET 3652); the 2008 outburst (cf. CBET 1501) occurred about 0.3 deg
earlier in solar longitude.  The authors thank all participants in the Global 
Meteor Network project.


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

                         (C) Copyright 2026 CBAT
2026 September 12                (CBET 5736)              Daniel W. E. Green