Draconids (DRA): 6 Οκτ. ως 10 Οκτ. Μέγιστο: 8 Οκτ. 2010

[Bi2L]

Draconids (DRA)

 

πηγη imo.net

http://www.imo.net/calendar/2010#dra

 

Active: October 6–10;

Maximum: October 8, 22h45m UT (λˆ = 195 .°4, but see below);

ZHR = periodic, up to storm levels;

Radiant: α = 262°, δ = +54°;

Radiant drift: negligible;

V∞ = 20 km/s;

r = 2.6;

TFC: α = 290°, δ = +65° and α = 288°, δ = +39° (β > 30° N).

 

The Draconids are primarily a periodic shower which produced spectacular, brief, meteor storms twice last century, in 1933 and 1946, and lower rates in several other years (ZHRs ~ 20–500+). Most detected showers were in years when the stream's parent comet, 21P/Giacobini-Zinner, returned to perihelion, as it did last in 2005 July. Its orbital period is currently about 6.6 years. In 2005 October, a largely unexpected outburst happened near the comet's nodal crossing time, around λˆ = 195 .°40–195 .°44, probably due to material shed in 1946. Visual ZHRs were ∼ 35, though radar detections suggested a much higher estimated rate, closer to ∼ 150. The peak was found in radio results too, but it did not record especially strongly that way. Outlying maximum times from the recent past have spanned from λˆ = 195 .°075 (in 1998; EZHRs ~ 700), equivalent to 2010 October 8, 14h55m UT, through the nodal passage time above, to λˆ195 .°63–195 .°76 (a minor outburst in 1999, not a perihelion-return year; ZHRs ~ 10–20), equating to 2010 October 9, 04h20m to 07h30m UT. The radiant is circumpolar from many northern hemisphere locations, but is highest during the first half of the night in early October. New Moon on October 7 makes this a perfect year to check for any activity, though none is anticipated until 2011 October, a little ahead of the comet's next return. Draconid meteors are exceptionally slowmoving, a characteristic which helps separate genuine shower meteors from sporadics accidentally lining up with the radiant.