(meteorobs) Meteor Activity Outlook for December 18-24, 2010

[lunro.imo.usa at cox.net]

During this period the moon reaches its full phase on Tuesday December 21st. At this time the moon lies opposite the sun and is above the horizon all night long from most locations. This is the worst time to attempt to view meteor activity as the bright moonlight will obscure all but the brightest meteors. The estimated total hourly rates for evening observers this week is near three from the northern hemisphere and two for observers south of the equator. For morning observers the estimated total hourly rates should be near ten from the northern hemisphere and nine 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. Rates are reduced during this period due to 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 18/19. 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 following showers are expected to be active this week. The detailed descriptions will be continued next week when the moonlight is not as intense. 

Antihelion (ANT) - 06:40 (100) +23    Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr

Monocerotids (MON) - 07:08 (107) +07   Velocity - 41km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Geminids (GEM) - 07:56 (119) +31   Velocity - 35km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr

Sigma Hydrids (HYD) - 08:56 (134) +00   Velocity - 61km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

December Leonis Minorids (DLM) - 10:44 (161) +31   Velocity - 71km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr

Coma Berenicids (COM) - 11:48 (177) +18   Velocity - 65km/sec.
Northern Hemisphere - 1 per hr. Southern Hemisphere - 1 per hr

Ursids (URS) - 14:12 (213) +75   Velocity - 33km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Clear Skies!
Robert Lunsford