(meteorobs) Meteor Activity Outlook for March 3-9, 2012

[Robert Lunsford]

During this period the moon reaches its full phase on Thursday March 8th. At that time the moon will be located opposite the sun in the sky and will be above the horizon the entire night. This weekend the waxing gibbous moon will set during the early morning hours, allowing a few hours of meteor viewing under dark conditions. The estimated total hourly rates for evening observers this week is near two for observers in the northern hemisphere and three for those south of the equator. For morning observers the estimated total hourly rates should be near six as seen from mid-northern latitudes and fifteen 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. Evening rates this week are reduced due to bright 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 March 3/4. 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 large Antihelion (ANT) radiant is currently located at 11:44 (176) +00. This position lies in western Virgo, only two degrees southwest of the fourth magnitude star Zavijava (Beta Virginis). Due to the large size of this radiant, Antihelion activity may also appear from the nearby constellations of Crater, Sextans, Corvus, southwestern Coma Berenicids, and eastern Leo as well as Virgo. This radiant is best placed near 0100 local standard time (LST), 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 30 km/sec., the average Antihelion meteor would be of slow velocity.

The Gamma Normids (GNO) is a weak shower best seen from the southern hemisphere. This shower is only visible south of forty degrees north latitude. The further one is located south (down to 50S) the better the radiant is situated in the sky. Expected rates from the southern hemisphere is currently less than one per hour, even with the radiant located high in the sky. The current radiant position lies at 16:00 (240) -52. This position lies in central Norma, three degrees southwest of the fourth magnitude star Gamma Normae. The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 56km/sec. the Gamma Normids would produce mostly swift meteors.

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

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

Antihelion (ANT) - 11:44 (176) +00   Velocity 30km/sec
Northern Hemisphere - 1 per hr Southern Hemisphere - 1 per hour

Gamma Normids (GNO) 16:00 (240) -52   Velocity 56km/sec
Northern Hemisphere - <1 per hr Southern Hemisphere - <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society