(meteorobs) quads maximum - predicted for 1250 UT Jan 3, 2009

[Thomas Ashcraft]

Active: 	January 1-5
Maximum: 	January 3 12h50m UT (?_o = 283°16)
ZHR = 	120 (can vary ~ 60-200)
Radiant: 	? = 230° ? = +49°
Radiant drift: 	see Table 6
v_? = 	41 km/s; r = 2.1 at maximum (but variable)
TFC: 	? = 242° ? = +75° and ? = 198° ? = +40° (? > 40° N)
IFC: 	before 0h local time ? = 150° ? = +70°

	? after 0h local time ? = 180° ? = +40° and ? = 240° ? = +70° (? > 40° N)





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> Eric,
>
> Here is info from the 2009 IMO meteor shower calendar:
> http://www.imo.net/calendar/2009
> ::::::
>
> The waxing crescent Moon will set near local midnight for the maximum of 
> the Quadrantids at northern hemisphere sites, from many of which, the 
> shower's radiant is circumpolar, in northern Boötes. As this area 
> attains a useful elevation only after local midnight, rising higher in 
> the sky towards morning twilight, this is excellent news. However, the 
> expected peak's timing falls poorly for land-based observers, except for 
> those in the extreme western areas of North America, on islands in the 
> North Pacific Ocean, and the extreme east of Russia. An interesting 
> challenge is to try spotting the occasional long-pathed shower member 
> from the southern hemisphere around dawn, but sensible Quadrantid 
> watching cannot be carried out from such places.
>
> The maximum timing above is based on the best-observed return of the 
> shower ever analysed, from IMO 1992 data, confirmed by radio results in 
> most years since 1996. The peak itself is normally short-lived, and can 
> be easily missed in just a few hours of poor northern-winter weather, 
> which may be why the ZHR level apparently fluctuates from year to year, 
> but some genuine variability is probably present too. For instance, 
> visual ZHRs in preliminary results from 2008 persisted for more than two 
> hours at close to their best, with the maximum itself centred around 
> three to four hours later than anticipated. An added level of complexity 
> comes from the fact that mass-sorting of particles across the meteoroid 
> stream may make fainter objects (radio and telescopic meteors) reach 
> maximum up to 14 hours before the brighter (visual and photographic) 
> ones, so observers should be alert throughout the shower. A few, but 
> apparently not all, years since 2000 seem to have produced a, primarily 
> radio, maximum following the main visual one by some 9-12 hours. Visual 
> confirmation of any repeat near this time in 2009 would fall ideally for 
> sites from Europe east to central Asia. Oddly, in 2008, there seemed to 
> be two possible radio Quadrantid peaks, but the first was apparently 
> about six hours /before/ the visual one, during an apparent 
> rates-plateau ahead of the main maximum in the visual data.
>
> Past observations have suggested the QUA radiant is diffuse away from 
> the maximum, contracting notably during the peak itself, although this 
> may be a result of the very low activity outside the hours near maximum. 
> Still-imaging and video observations from January 1-5 would be 
> particularly welcomed by those investigating this topic, using the IFCs 
> and TFCs given above, along with telescopic and visual plotting results.
>
> ::::::::::
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