Meteor Activity Outlook for September 26-October 2, 2009

Meteor activity in general increases in October when compared to September. A major shower (the Orionids) is active most of the month along with several minor showers. Both branches of the Taurids become more active as the month progresses, providing slow, graceful meteors to the nighttime scene. The Orionids are the big story of the month reaching maximum activity on the 22nd. This display can be seen equally well from both hemispheres which definitely helps out observers located in the sporadic-poor southern hemisphere this time of year.

During this period the moon progresses from its first quarter phase on September 26 to nearly full. This weekend the half illuminated moon sets near 0100 Local Daylight Time (LDT) and will not interfere with observing during the prime morning hours. Unfortunately, with each passing night, the waxing gibbous moon will set later and later shortening this dark window between moonset and dawn. By Friday October 2, the nearly full moon will be in the sky nearly the entire night making meteor observing difficult at best. The estimated total hourly rates for evening observers this week is near four as seen from the northern hemisphere and two from the southern hemisphere. For morning observers the estimated total hourly rates should be near eighteen from the northern hemisphere and seven 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 bright moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning September 26/27. 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 center of the large Southern Taurid (STA) radiant lies at 01:22 (020) +06. This position also lies in southeastern Pisces, two degrees east of the faint star Zeta Piscium. Since the radiant is so large, any meteor from Pisces, northern Cetus, or western Aries could be a candidate for this shower. The radiant is best placed near the meridian at 0200 LDT, but activity may be seen all night long. Striking the atmosphere at 29 km/sec., the average Southern Taurid meteor travels slowly through the skies.

A recent study of video radiants by Sirko Molau has revealed a radiant in Lynx active from September 29 through October 2. Maximum activity occurs on September 29th from a radiant located at 07:21 (110) +48. This position is located in a remote area of western Lynx. The nearest bright star is Castor (Alpha Geminorum), which lies sixteen degrees to the south. The radiant rises near 2300 (11pm) for mid-northern latitude observers and lies highest in a dark sky during the last hour before the start of morning twilight. Meteors from the September Lyncids (SLY) strike the atmosphere at 68km/sec., which would produce mostly swift meteors, lasting a fraction of a second. Expected rates would be less than one per hour, no matter your location. This shower is best seen from the northern hemisphere where the radiant climbs high in the sky before dawn.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately fifteen 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 four per hour as seen from rural observing sites and one per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Rates are reduced during the evening hours 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 September 26/27, but may be used all week.