Meteor Activity Outlook for March 21-27, 2009

March is the slowest month for meteor activity. No major annual showers are active and only two very weak minor showers produce activity this month. The sporadic rates continue a slow decline as seen from the mid-northern latitudes and mid-southern rates reach a first half minimum. There is not much to look forward to this month expect for the evening fireballs that seem to peak this time of year from the northern hemisphere. This could be due to the fact the antapex lies highest this time of year during the evening hours.

During this period the moon reaches its new phase on Thursday March 26th. At this time the moon lies near the sun in the sky and cannot be seen at night. This weekend the waning crescent moon will rise during the morning hours. At this phase it will not cause much interference. The moonlight that is present can be easily avoided by facing away from it. The estimated total hourly rates for evening observers this week is near three as seen from the northern hemisphere and four for those situated south of the equator. For morning observers the estimated total hourly rates should be near eight for those located in the mid-northern hemisphere (45 N) and twelve for those viewing from the mid-southern hemisphere (45 S). Locations between these two extremes would see activity between the listed figures. 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. Meteor rates are slightly reduced during the morning hours during this period due to lunar interference.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning March 22. 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 wide Antihelion (ANT) radiant is now centered at 12:56 (194) -06. This area of the sky lies in central Virgo, seven degrees northwest of the first magnitude star Spica (Alpha Virginis). This radiant is also best placed near 0200 LDT. Due to the large size of this radiant, any meteor radiating from northern Corvus or Virgo could be a candidate for this shower. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30km/sec., the average Antihelion meteor would be of medium-slow speed.

The Gamma Normids (GNO) are now past maximum and barely active from a radiant located at 16:28 (247) -49. This area of the sky is located in eastern Norma, two degrees south of the fourth magnitude star Epsilon Normae. These meteors are best seen between 0500 and 0600 local daylight time, when the radiant lies highest above the horizon. This shower is best seen from the southern hemisphere, where the radiant lies high in the sky at dawn. Meteors from this shower are not visible north of 40 degrees north latitude and also poorly seen throughout most of the northern hemisphere. An occasional shower member may be seen from the northern tropics, shooting upwards from the southern horizon. At 56 km/sec. the Gamma Normids will usually produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately six Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near ten per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Sporadic rates are slightly reduced during the morning hours due to lunar interference.

The table below presents a summary of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week.