• From: G7IZU ALERT <g7izu@xxxxxxxxxxxxxxxxxxx>
  • To: alert-vh@xxxxxxxxxxxxx
  • Date: Thu, 01 Dec 2011 06:01:09 +0000

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to the G7IZU Meteor Activity Alert Service (VERY HIGH ALERT).

G7IZU RRD NEWS - 01 DEC 2011

The last few weeks of the year will the Ursids meteor shower in mid-December. 
Activity is not normally great, but in the past outbursts have been witnessed. 

From IMO:

"A very poorly-observed northern hemisphere shower, but one which has produced 
at least two major outbursts in the past 70 years, in 1945 and 1986. Several 
other rate enhancements have been reported as well, recently in 1988, 1994, 
2000, 2006, 2007 and 2008 (which latter apparently produced at least two peaks 
with EZHRs of ~ 30?35, and activity around half this level or better for 
perhaps nine to ten hours). Other similar events could have been missed easily 
due to poor weather or too few observers active.

"All forms of observation can be used for the shower, since many of its meteors 
are faint, but with so little work carried out on the stream, it is impossible 
to be precise in making statements about it. The radio maximum in 1996 occurred 
around ?? = 270.8°, for instance, which might suggest a slightly later maximum 
time in 2011 of December 23, ~ 04h UT. Models developed by Esko Lyytinen and 
Jérémie Vaubaillon have suggested the relative proximity of the shower's parent 
comet, 8P/Tuttle, last at perihelion in January 2008, seems to have been what 
has influenced some of the recent events. Jérémie's model has further indicated 
there could be another peak this year, around 16h11m UT on December 22, with 
fairly typical ZHRs of ~ 12. VID indicated a maximum around ?? = 270.5°, equal 
to December 22, ~ 21h UT. The Ursid radiant is circumpolar from most northern 
sites (thus fails to rise for most southern ones), though it culminates after 
daybreak, and is highest in the sky later in 
 the night. New Moon on December 24 means observing conditions are perfect for 
checking whatever takes place. The ~ 16h timing would be available overnight to 
observers from eastern European longitudes east across all of Asia; the ~ 21h 
peak would be good for European sites east across most of Asia; and the 02h?04h 
peaks would fall best for places from North America east across Europe".

My 143 MHz GRAVES system is switched on again for a short period. Once the 55 
MHz TV transmitter in Portugal is turned off early next year I'll switch my 
main system to 143 MHz. I will also concentrate more on solar observation via 
the VLF system, which is now watching six or seven transmissions between 19 and 
77.5 kHz, and do some monitoring on the HF bands. 

A new radio meteor observation group nicknamed S.P.A.M is growing out of the 
original system I set up at the Norman Lockyer Observatory in early 2010. The 
group have observers across southern England from Tiverton in the west to 
Southend in the east, all monitoring GRAVES. There's a webpage showing the 
output from six of the receive stations updated every 40 seconds: 


Peak dates/times/ZHR

2011-12-17 to 2011-12-26 ZHR 10 (occ var upto 50)
Peak 2011-12-23 02h to 04h UT

2011-12-28 to 2012-01-12 ZHR 6~200 var
Peak 2012-01-04 07h20 UT

Predictions are from the IMO Meteor Shower Outlook and Calendar.


55 MHz system ON
143 MHz system ON
VLF SID detector system ON


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