Meteor Activity Outlook for December 5-11, 2009
December 3, 2009 3 Comments
The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 13. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Unfortunately this year the bright moon spoils the show during the first week of the month. During the second week of December the moon will pass its last quarter phase and will not be such a nuisance .
As seen from the southern hemisphere the sporadic rates are increasing toward a January maximum. Shower rates are also good but the Geminids suffer a bit from the lower elevation seen from southern locations. Still with the warmer weather now occurring south of the equator, December is a great time to view celestial fireworks.
During this period the moon reaches its last quarter phase on Wednesday December 9th. On that date the moon lies ninety degrees west of the sun and rises near midnight local standard time (LST). This weekend the waning gibbous moon will rise during the evening hours and remain in the sky the remainder of the night. The bright glare from the gibbous moon will make it difficult to view any meteor activity. Once the moon passes its last quarter phase the moonlight becomes less of a problem. The estimated total hourly rates for evening observers this week is near three as seen from the northern hemisphere and two from the southern hemisphere. For morning observers the estimated total hourly rates should be near ten from the northern hemisphere and seven as seen from the southern hemisphere. The actual rates will also depend on factors such as
personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Morning rates are reduced during this period due to moonlight.
The radiant positions and rates listed below are exact for Saturday night/Sunday morning December 5/6. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week. The full descriptions of each active meteor shower will continue next week when
the moon becomes less of a nuisance to observers.
The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week long.
Shower Name RA DEC Vel Rates km/s NH SH PHO Phoenicids 01h 12m -53 18 <1 <1 NTA Northern Taurids 05h 16m +26 29 2 1 MON Monocerotids 06h 32m +08 41 <1 <1 GEM Geminids 07h 10m +33 35 2 <1 PUP Puppids-Velids 08h 10m -45 40 <1 <1 HYD Sigma Hydrids 08h 16m +03 61 <1 <1 PSU Psi Ursae Majorids 11h 19m +43 61 <1 <1 DAD Alpha Draconids 13h 34m +60 44 <1 <1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere