(meteorobs) Meteor Activity Outlook for December 10-16, 2011

[Robert Lunsford]

During this period the moon reaches its full phase on Saturday December 10th. At this time the moon will lie above the horizon the entire night and will severely impact meteor observing by obscuring all but the brightest meteors. As this week progresses the moon’s phase will wane and it will rise approximately forty-five minutes later each night. Toward the end of the week there will be a window of opportunity to view evening activity under dark skies between the end of dusk and moon rise. The estimated total hourly rates for evening observers this week is near two as seen from the northern hemisphere and one as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near eight as seen from mid-northern latitudes and five from mid-southern latitudes. 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. All rates are reduced due to intense moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning December 10/11 These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning. Detailed descriptions of each shower will continue next week when the moonlight is less of a problem.

Antihelions (ANT) - 06:04 (091) +23   Velocity - 30km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr

Monocerotids (MON) - 06:45 (101) +08   Velocity - 41km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Geminids (GEM) - 07:22 (110) +33   Velocity - 35km/sec.
Northern Hemisphere - 3 per hr. Southern Hemisphere - 2 per hr

Puppid-Velids (PUP) - 08:22 (125) -45   Velocity - 40km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 1 per hr

Sigma Hydrids (HYD) - 08:32 (128) +02   Velocity - 61km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

December Leonis Minorids (DLM) - 10:15 (154) +34   Velocity - 64km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Psi Ursa Majorids (PSU) - 11:49 (177) +41   Velocity - 61km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

December Alpha Draconids (DAD) - 13:54 (208) +58  Velocity - 44km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Clear Skies!
Robert Lunsford
American Meteor Society