Meteor Activity Outlook for March 16-22, 2007

March provides some of the lowest meteor activity of the year. This is especially true for northern observers. There are no major showers active this month and only one minor shower that peaks this month (Gamma Normids), and its existence is suspect. This suspected radiant is best seen from the southern hemisphere. The only other radiant active this month (other than the declining Delta Leonids) is the antihelion radiant, now situated in Virgo. On the bright side, March is prime time for evening fireballs and many have been reported during star parties and Messier marathons this month.

During this period the moon reaches its new phase on Monday March 19. At this time the moon will be located near the sun and will not interfere with meteor observing this week. The estimated total hourly rates for evening observers this week is near two for those north of the equator and three for observers south of the equator. For morning observers the estimated total hourly rates should be near ten for northern observers and fifteen for those south of the equator. These rates assume that you are watching from rural areas away from all sources of light pollution. 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 positions listed below are exact for Saturday night/Sunday morning March 17/18. 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. Doing this 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 Antihelion (ANT) radiant is now centered at 12:40 (190) -05. This area of the sky is centered in central Virgo, three degrees south of the famous third magnitude double star Porrima (Gamma Virginis). This radiant is best placed near 0200 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

The Gamma Normids (GNO) are a bit suspect at this time. Not only is the activity suspect but the radiant position is not positively known. The published date of maximum activity is March 14 but newer data may show that it occurs a few days later. The published radiant is currently located at 16:12 (243) -50. This position lies in central Norma, two degrees west of the fourth magnitude star Gamma Normae. Predicted ZHR's are near four at maximum activity. Due to the far southern declination of the radiant, this shower is not well seen north of the northern equatorial regions. This area of the sky is best placed near 0600 LDT when it lies highest in the sky. At 56 km/sec. the Gamma Normids normally produce meteors of swift angular velocities.

Sporadic rates are slowing decreasing for observers in the northern hemisphere and slightly rising for those south of the equator. One would expect to see perhaps eight random meteors during the last hour before dawn from rural observing sites located in the northern hemisphere. During the first dark hour after the end of evening twilight, perhaps two random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near five per hour. Late morning sporadic rates seen from the southern hemisphere are now near a dozen per hour from rural observing sites. During the first dark hour after the end of evening twilight, perhaps three random meteors can be seen per hour, increasing to six by midnight.