Meteor Activity Outlook for January 18-24, 2008

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 full phase on Tuesday January 22. At this time the moon will be in the sky all night long. Successful observations can be undertaken this weekend if your sky is clear and transparent or one could wait until the moon lies low in the sky just before dawn. The estimated total hourly rates for evening observers this week is near two no matter your location. For morning observers the estimated total hourly rates should be near nine for those located in the mid-northern hemisphere (45 N) and eight for those viewing from the mid-southern hemisphere (45 S). These rates assume that you are watching from rural areas away from all sources of light pollution. 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 this week due to intense moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning January 19/20. 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 wide Antihelion (ANT) radiant is now centered at 08:48 (132) +16. This area of the sky lies in southern Cancer, two degrees southeast of the fourth magnitude star Delta Cancri. This radiant is best placed near 0100 local standard time when it lies on the meridian and is highest in the sky. Actually any meteor from Cancer or extreme western Leo 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 Coma Berenicids (COM) are active from a radiant located at 13:28 (202) +13. This area of the sky is located in a remote area of northern Virgo. The nearest bright star is Arcturus (Alpha Bootis), located some twelve degrees to the northeast. Current rates would be near less than one shower member per hour no matter your location. These meteors are best seen near 0600 local standard time when the radiant lies highest above the horizon. At 65 km/sec. the Coma Berenicids will usually produce meteors of swift velocity.

Sporadic rates are now slowly falling for observers in the northern hemisphere and have reached a first annual maximum for those located south of the equator. One would expect to see approximately six random meteors during the last hour before dawn from rural observing sites in the northren hemisphere and seven from the southern hemisphere. During the first dark hour after the end of evening twilight, perhaps two random meteors can be seen per hour, no matter your location. Moonlight reduces 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.