8P/Tuttle及小熊座流星雨

URSID METEORS: Comet 8P/Tuttle is coming and it is bringing a meteor shower with it. "We could be in for a Merry surprise on Dec. 22nd when Earth passes through a trail of comet dust," says astronomer Peter Jenniskens of the SETI Institute. Previous returns of Comet Tuttle to the inner solar system have been attended by outbursts of meteors, most recently in 1980 and 1994. During those flurries, dozens of meteors per hour streamed from the constellation Ursa Minor--hence the name of the shower, "the Ursids."

                               
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Above: Comet 8P/Tuttle photographed Dec. 2nd by Chris Schur of Payson, AZ. The 7th magnitude comet is visible through binoculars in the constellation Cassiopeia. [sky map] [ephemeris] [orbit] [more]

Although Ursids have a reputation for being faint, "we are not certain about this," says Jenniskens. "Because winter weather keeps many observers indoors, Ursid outbursts have never been widely observed and they may contain a fair number of bright meteors. We have a lot to learn." That's why he hopes sky watchers will keep an eye on the northern sky this weekend; Ursid meteors emerge not far from the north star, Polaris. According to models by Jenniskens and colleagues, the peak will occur between 2100 and 2200 UT (4-5 pm EST) on Dec. 22nd with meteors visible as much as four hours before and after that time. Anything could happen, from a dud to a blast. Bundle up and look!



同时看到母体彗星和由彗星形成的流星雨还是很难得的，２２日２１：００－２２：００（ＵＴ），这一天象即将上演，峰值发生在北京时间２３日凌晨５－６点，农历十四，不过峰值时间月光的影响已经很小，而彗星离地球只有０.３１AU.

星历表：
Ephemeris of comet 8P Tuttle
日期        　  时间 (UT) 　　  赤经            赤纬       　R (AU)  D(AU)     E.L　亮度
23 12月 2007 00:00:00  00h 54m 56.0s  +57°32' 46"  1.1564  0.3108  116.5  6.7  
24 12月 2007 00:00:00  01h 00m 26.3s  +54°48' 13"  1.1496  0.3005  116.5  6.6  
25 12月 2007 00:00:00  01h 05m 40.6s  +51°51' 37"  1.1430  0.2910  116.4  6.5  
26 12月 2007 00:00:00  01h 10m 39.9s  +48°42' 55"  1.1366  0.2824  116.2  6.4  
27 12月 2007 00:00:00  01h 15m 25.4s  +45°22' 18"  1.1303  0.2747  115.8  6.3  
28 12月 2007 00:00:00  01h 19m 58.0s  +41°50' 23"  1.1241  0.2681  115.2  6.2  
29 12月 2007 00:00:00  01h 24m 18.8s  +38°08' 09"  1.1181  0.2625  114.5  6.1  
30 12月 2007 00:00:00  01h 28m 28.5s  +34°17' 02"  1.1123  0.2582  113.6  6.0  
31 12月 2007 00:00:00  01h 32m 27.8s  +30°18' 52"  1.1066  0.2551  112.6  5.9  
01  1月 2008 00:00:00  01h 36m 17.6s  +26°15' 55"  1.1011  0.2532  111.4  5.8  
02  1月 2008 00:00:00  01h 39m 58.4s  +22°10' 38"  1.0958  0.2527  110.0  5.8  
03  1月 2008 00:00:00  01h 43m 30.8s  +18°05' 42"  1.0906  0.2535  108.5  5.8  
04  1月 2008 00:00:00  01h 46m 55.3s  +14°03' 40"  1.0857  0.2556  106.9  5.8  
05  1月 2008 00:00:00  01h 50m 12.5s  +10°06' 55"  1.0809  0.2590  105.3  5.7  
06  1月 2008 00:00:00  01h 53m 22.7s  +06°17' 33"  1.0762  0.2636  103.6  5.7  
07  1月 2008 00:00:00  01h 56m 26.4s  +02°37' 12"  1.0718  0.2693  101.9  5.8  
08  1月 2008 00:00:00  01h 59m 24.0s  -00°52' 53"  1.0676  0.2760  100.2  5.8  
09  1月 2008 00:00:00  02h 02m 15.9s  -04°11' 55"  1.0635  0.2837   98.6  5.8  
10  1月 2008 00:00:00  02h 05m 02.3s  -07°19' 29"  1.0597  0.2923   97.0  5.8  
11  1月 2008 00:00:00  02h 07m 43.5s  -10°15' 31"  1.0560  0.3017   95.5  5.9  
12  1月 2008 00:00:00  02h 10m 19.9s  -13°00' 12"  1.0526  0.3118   94.1  5.9  
13  1月 2008 00:00:00  02h 12m 51.6s  -15°33' 54"  1.0494  0.3226   92.7  6.0  
14  1月 2008 00:00:00  02h 15m 19.0s  -17°57' 08"  1.0464  0.3339   91.4  6.0  
15  1月 2008 00:00:00  02h 17m 42.3s  -20°10' 30"  1.0435  0.3456   90.2  6.1  
16  1月 2008 00:00:00  02h 20m 01.5s  -22°14' 39"  1.0409  0.3578   89.0  6.1  
17  1月 2008 00:00:00  02h 22m 17.1s  -24°10' 12"  1.0386  0.3704   87.9  6.2  
18  1月 2008 00:00:00  02h 24m 29.1s  -25°57' 49"  1.0364  0.3833   86.9  6.2  
19  1月 2008 00:00:00  02h 26m 37.6s  -27°38' 07"  1.0345  0.3965   86.0  6.3  
20  1月 2008 00:00:00  02h 28m 43.0s  -29°11' 41"  1.0328  0.4099   85.1  6.3  
21  1月 2008 00:00:00  02h 30m 45.2s  -30°39' 04"  1.0313  0.4235   84.2  6.4  



[ 本帖最后由 suhuasky 于 2007-12-21 23:08 编辑 ]

这颗彗星我已经多次观测到，表现中规中矩，一切按照预报的发展，亮度增加迅猛，当然和17P是没得比了！

URSID OUTBURST: "Initial reports from observers in Europe seem to confirm that an outburst of Ursids happened close to the predicted peak time," says forecaster Peter Jenniskens of the SETI Institute. "First reports put the rate around ZHR = 25/hr (predicted was 40 - 70/hr). The peak time may have been around 21:15 UTC (predicted 20.0 - 22.2 h UTC) on Dec. 22nd."

This bright Ursid flew overhead near Santa Cruz, California:



"This meteor appeared right in the center of the field of view," report photographers Brian Murahashi and Jim Albers. "Wow! There were bright pink and violet colors, multiple flares, and a persistent train, which we captured on our all sky camera."

The intensity and timing of the flurry is in good accord with predictions that Earth would run into a stream of dust from Comet 8P/Tuttle on Dec. 22nd. Now that the meteor shower is over, attention turns to the comet itself. After a 13.6 year absence, 8P/Tuttle is once again traveling through the inner solar system. At closest approach to Earth on Jan. 1st and 2nd, 2008, the comet, will brighten to 5th or 6th magnitude--a fine target for backyard telescopes and digital cameras.