(meteorobs) Meteor Activity Outlook for September 1-7, 2012

[Robert Lunsford]

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.

During this period the moon wanes from its full phase to nearly last quarter. These are the worst circumstances possible for meteor watchers as the moon will interfere with observing all week long as it will be present in the morning sky when meteor rates are at their best. The bright glare of the moonlight will obscure all but the brightest meteors reducing rates significantly. The estimated total hourly meteor rates for evening observers this week is near three for observers located at mid-northern latitudes and two for observers in mid-southern latitudes. For morning observers the estimated total hourly rates should be near eight from the mid-northern hemisphere and four from the mid-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. 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 1/2. 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 radiants are expected to be active this week. Detailed descriptions of each source will continue next week when moonlight will not be such a problem.

Antihelions (ANT) - 23:28 (352) -02   Velocity 30km/sec
Northern Hemisphere - 1 per hr   Southern Hemisphere - 1 per hour

September Epsilon Perseids (SPE)  03:52 (043) +41  Velocity 61km/sec
Northern Hemisphere - 1 per hr   Southern Hemisphere - <1 per hour

IMO #149  04:52 (073) +45   Velocity 70km/sec
Northern Hemisphere - <1 per hr   Southern Hemisphere - <1 per hour

Aurigids (AUR) - 06:16 (094) +40   Velocity 67km/sec
Northern Hemisphere - <1 per hr   Southern Hemisphere - <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society