Meteor Activity Outlook for September 15-21, 2006

Although there are no major showers active in September, meteor rates in the northern hemisphere continue to be strong. Minor activity from the constellations of Auriga, Perseus, and Taurus, as well as strong sporadic rates, produce these impressive rates. Rates as seen from the southern hemisphere have dropped off significantly since the July peak. Other than weak sporadic rates, only the antihelion radiant produces any notable shower activity in the southern skies.

This week the moon wanes from a half phase to a very slender crescent. With each passing night the moon will rise later and will pose less of a problem to observers. The estimated total hourly rates for evening observers this week is near three for those north of the equator and one for those south of the equator. For morning observers the estimated total hourly rates should be near fourteen for those in the northern hemisphere and six for those south of the equator. 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 by moonlight.

The radiant positions listed below are exact for Saturday night/Sunday morning September 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. 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.

These showers are active this week:

The large Antihelion (ANT) radiant is now centered at 00:28 (007) +03. This area of the sky is centered in southern Pisces, six degrees southwest of the fourth magnitude star Delta Piscium. This radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour regardless of your location. With an entry velocity of 30 km/sec., the average antihelion meteor would be of medium-slow speed.

The Delta Aurigids (DAU) reach a weak peak on October 4. Current rates would most certainly be less than one per hour. The radiant is located at 04:32 (68) +48. This portion of the sky lies in eastern Perseus, eight degrees west of the brilliant zero magnitude star Capella (Alpha Aurigae). Due to the extreme northern declination of this radiant, this shower is only visible from the southern tropics northward. The radiant is best placed near 0500 LDT, when it lies on the meridian. At 64km/sec.,the average Delta Aurigid is swift.

Sporadic rates continue to climb slowly for observers located in the northern hemisphere. One would expect to see perhaps twelve random meteors during the last hour before dawn from rural observing sites. During the first dark hour after the end of evening twilight, perhaps three random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near seven per hour. Sporadic rates seen from the southern hemisphere have fallen drastically since the July maximum. One would see approximately four random meteors per hour during the last hour before dawn and one per hour during the first dark hour after the end of evening twilight. Rates near midnight would be near two per hour. Morning rates are slightly reduced by moonlight.

Clear Skies!