Meteor Activity Outlook for September 10-16, 2011

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

September offers longer nights in the northern hemisphere that tend to be less hazy than those experienced in mid-summer. In the sky, no major showers are visible from either hemisphere but the northern hemisphere enjoys the advantage of higher sporadic rates. Most of the shower activity this month is produced from the Perseus–Aurigid complex active this time of year. These showers rarely produce more than five meteors per hour but still manage to produce most of the shower activity seen this month. Unfortunately the Perseus–Aurigid complex lies too low in the northern sky for southern hemisphere observers to view very well. Video studies have shown that the Southern Taurids are visible as early as September 7th therefore after this date the Antihelion radiant will no longer be listed until the Taurid showers end in December. The Antihelion meteors are still active but their radiant is superimposed upon that of the more numerous Taurids, therefore it is impossible to properly separate these meteors. Observers in the southern hemisphere suffer from some of their lowest rates of the year this month. The Southern Taurid radiant is not too badly placed so observers south can expect to see a little of this activity this month.

Meteor season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its full phase on Monday September 12th. At this time the moon will lie opposite the sun and will be in the sky all night long. This is the worst time to try and view meteor activity this month as the intense moonlight will obscure all but the brightest meteors. Conditions will not improve until the moon wanes to its last quarter phase and does not rise until near 0100 local daylight time (LDT). The estimated total hourly rates for evening observers this week is near two as seen from the northern hemisphere and one as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near eight as seen from mid-northern latitudes and five 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. Rates are reduced during this period due to the intense moonlight.

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 11/12. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

Detailed descriptions of the active showers will continue next week when the moonlight conditions will be more favorable. The following showers are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning.

Shower Name                  RA     DEC   Vel     Rates
                                          km/s   NH    SH
STA Southern Taurids       00h 48m  +03    27     1     1
SIC Sept Iota Cassiopeiids 02h 27m  +64    50    <1    <1
SPE Sept Epsilon Perseids  03h 12m  +41    66    <1    <1
NUE Nu Eridanids           04h 36m  +03    68     1     1

RA - Right Ascension
DEC - Declination
Vel - Velocity relative to Earth (in km per sec)
Rates - Rate of visible meteors per hour from a dark site
NH - Northern Hemisphere
SH - Southern Hemisphere