Meteor Activity Outlook for September 24-30, 2011

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During this period the moon reaches its new phase on Tuesday September 27th. At this time the moon will lie near the sun and will not be visible at night. This weekend the waning crescent moon will rise during the late morning hours but will not interfere with meteor observing. The estimated total hourly rates for evening observers this week is near four as seen from the northern hemisphere and three as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near eleven as seen from mid-northern latitudes and six from mid-southern latitudes. 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.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning September 24/25. 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 shower is expected to be active this week:

The Southern Taurid (STA) radiant is now centered at 01:16 (019) +06. This area of the sky lies on the Pisces/Cetus border, six degrees southeast of the fourth magnitude star Epsilon Piscium. This radiant is best placed near 0200 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time should be near one per hour no matter your location. With an entry velocity of 27 km/sec., the average Southern Taurid meteor would be of medium-slow speed. While looking at this area of the sky, notice how bright the variable star Mira (Omicron Ceti) is these nights. It normally is too dim to be seen with the naked eye but now stands at second magnitude, nearly the brightest star in the constellation of Cetus the whale. It lies approximately fifteen degrees southeast from the center of the STA radiant or just six degrees southeast of the fourth magnitude star Al Rischa (Alpha Piscium). It is probably near peak magnitude and will soon begin fading.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately ten sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near five 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.

The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.

RA (RA in Deg.) DEC Km/Sec Local Daylight Time North-South
Southern Taurids(STA) Oct 10 01:16 (019) +06 27 02:00 1 – 1 II


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