(meteorobs) Meteor Activity Outlook for January 23-29, 2010

[Robert Lunsford]

January sees a peak of sporadic activity for the southern hemisphere while rates seen north of the equator begin a steady downward 
turn that continues throughout the first half of the year. The sporadic activity is good for both hemispheres, but not as good as it 
was for northern observers in December. Once the Quadrantids have passed the shower activity for January is very quiet.

During this period the moon reaches its first quarter phase on Saturday January 23rd. At this time the moon will be limited to the 
evening hours and will set near midnight local standard time (LST). As the week progresses the moon begins to interfere into the 
active morning hours as it sets later and later with each passing night. Toward the end of the period the nearly full moon will be 
in the sky nearly all night long. This will make observations difficult at best. The estimated total hourly rates for evening 
observers this week is near three no matter your location. For morning observers the estimated total hourly rates should be near 
fifteen from the northern hemisphere and sixteen 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. 
Evening rates are reduced by moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning January 23/24. 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 radiants are expected to be active this week:

The wide Antihelion (ANT) radiant is now centered at 09:08 (137) +15. This area of the sky lies in eastern Cancer. The bright orange 
planet Mars, now near opposition, lies to northwest of this position. This radiant is best placed near 0100 LST when it lies on the 
meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from northwest Hydra, 
western Leo, or Cancer could be a candidate for this shower. Rates at this time should be near two per hour as seen from the 
northern hemisphere and one per hour for observers located south of the equator. With an entry velocity of 30 km/sec., the average 
Antihelion meteor would be of medium-slow speed.

The December Leonis Minorids (DLM) are near the end of their activity period. A few stragglers from this radiant may still be seen 
from a radiant located at 12:46 (192) +15. This position lies in southern Coma Berenices. The nearest star of note would be third 
magnitude Epsilon Virginis, located five degrees to the southeast. These meteors are best seen near 0500 LST when the radiant lies 
highest above the horizon. This shower peaked on December 20th so current rates would be near less than one per hour no matter your 
location. At 64km/sec. the December Leonis Minorids produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately thirteen Sporadic meteors per hour during the 
last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern 
hemisphere (45S), morning rates would be near fifteen per hour as seen from rural observing sites and two per hour during the 
evening hours. Locations between these two extremes would see activity between the listed figures. Moonlight interferes with evening 
rates during this period.

The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday 
night/Sunday morning.

Antihelion (ANT)) - 09:08 (137) +15    Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 1 per hr.

December Leonis Minorids (DLM) - 12:46 (192) +15  Velocity - 64km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: 
http://www.amsmeteors.org/showers.html#X2009

Clear Skies!
Robert Lunsford
American Meteor Society