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2008年1月 象限儀座流星雨預報
（2007年12月08日 15:07:13）
來源︰IMO
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□作者:
[1]
Quadrantids (QUA)
Active: January 1 — 5
Maximum: January 4 - 06h40m UT (λsol = 283°16)
ZHR = 120 (can vary ~ 60 — 200)
Radiant: α = 230°; δ = +49°
Radiant drift: see Table 6
vinf = 41 km/s; r = 2.1 at maximum but variable
TFC: α = 242°; δ = +75° and α = 198°; δ = +40° (β > 40° N)
IFC: before 0h local time α = 150°; δ = +70°
after 0h local time α = 180°; δ = +40° and
α = 240°; δ = +70° (β > 40° N)
A virtually moonless maximum of the Quadrantids opens the northern meteor watchers' year very well, with a waning crescent Moon, four days from new, which rises only around or after 04h at mid northern latitudes, so it will be little nuisance. From many northern locations, the shower's radiant is circumpolar, in northern Boötes, but it attains a useful elevation only after local midnight, rising higher in the sky towards morning twilight. Consequently, eastern North American longitudes east to those of extreme western Europe and North Africa will be the most favoured places to catch the shower's best, if the peak keeps to time. 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 given 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 1998 persisted for over two hours at their best. 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 2008 would fall ideally for sites from East Asia east to sites around the eastern North Pacific Ocean.
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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責任編輯:skylook
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上一篇︰2008年1月重要天象預告
下一篇︰今年雙子座流星雨中國處于全球最佳觀測位置
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