Meteor Activity Outlook for January 16-22, 2010

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 progresses from its new phase to nearly half illuminated. The waxing crescent moon will be limited to the evening sky and will not interfere with the choice morning hours. 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 16/17. 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 wide Antihelion (ANT) radiant is now centered at 08:36 (129) +17. This area of the sky lies in central Cancer, close to the faint star Theta Cancri. This radiant is best placed near 0100 local standard time (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 eastern Gemini, 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.

Studies of the IMO's video database by Sirko Molau has shown a radiant active in Cancer this time of year. This radiant is different from the nearby Antihelion source but the meteors have essentially the same entry velocity. Activity from the Southern Delta Cancrids (SCC) begin to appear on January 14th and peak four nights later. On the 14th the radiant is located at 08:39 (130) +10. This position lies in southern Cancer, just north of the five faint stars that make up the head of Hydra. These meteors are best seen near 0100 LST when the radiant lies highest above the horizon. Hourly rates from this shower will be less than one per hour no matter your location. At 29km/sec. the Southern Delta Cancrids produce meteors of medium-slow velocity.

The December Leonis Minorids (DLM) are active from a radiant located at 12:22 (186) +18. This position lies in southwestern Coma Berenices near the faint star 11 Comae Berenices. 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 table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.