Meteor Activity Outlook for January 17-23, 2009

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 it last quarter phase on Sunday January 18th. At this time the moon lies ninety degrees west of the sun and rises near midnight, local standard time (LST). Next week the waning crescent moon rises later in the morning with each passing night. This opens the window of opportunity to view meteor activity is a truly dark sky. 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 ten for those located in the mid-northern hemisphere (45 N) and twelve for those viewing from the mid-southern hemisphere (45 S). Locations between these two extremes would see activity between the listed figures. 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. Morning rates are slightly reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning January 17/18. 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 07:44 (130) +16. This area of the sky lies in central Cancer, two degrees southwest of the fourth magnitude star Delta Cancri. In fact, up to just a few years ago these antihelion meteors were known as the Delta Cancrids. 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 extreme eastern Gemini, Cancer, or western Leo could be a candidate for this shower. Rates at this time should be near three per hour as seen from the northern hemisphere and two 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 12:32 (188) +19. This area of the sky is located in a remote area of central Coma Berenices, twelve degrees northeast of the second magnitude star Denebola (Beta Leonis). These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. Rates should currently be near one per hour as seen from the northern hemisphere and less than one per hour as seen from locations south of the equator. At 64 km/sec. the Coma Berenicids will usually produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately eight 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 ten 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. Morning rates are reduced due to moonlight.

The table below presents a summary of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week.