(meteorobs) Meteor Activity Outlook for March 20-26, 2010

[Robert Lunsford]

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 radiant lies highest above the horizon this time of 
year during the evening hours.

During this period the moon reaches its first quarter phase on Tuesday March 23th. At this time the moon lies ninety degrees east of 
the sun and sets near 0100 local daylight time (LDT) for the mid-northern latitude observer. The estimated total hourly rates for 
evening observers this week is near two for northern observers and three for those viewing from south of the equator. For morning 
observers the estimated total hourly rates should be near ten from the northern hemisphere and fourteen as seen from the 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. Evening rates are reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning March 20/21. 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 12:52 (193) -06. This area of the sky lies in central Virgo, four degrees 
southeast of the famous third magnitude double star Porimma (Gamma Virginis). This radiant is best placed near 0200 local daylight 
time (LDT) when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor 
radiating from Crater, Corvus, southern Coma Berenices, 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 30 km/sec., the average Antihelion meteor would be of 
medium-slow speed.

Activity from the short-lived Zeta Serpentids (ZSR) begins on Tuesday morning March 23. This shower reaches maximum activity one 
night later from a radiant located at 17:04 (256) -04. This position lies in central Ophiuchus, one degree northeast of the faint 
star 30 Ophiuchi. The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark 
sky. At 64km/sec. the Zeta Serpentids would produce mostly swift meteors. The last of these meteors will be seen on Saturday, March 
27th. Expected rates, even at maximum is less than one shower member per hour.

The last of the Gamma Normids (GNO) will be seen this weekend. 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 now less than one per hour, even with the radiant located high in the sky. Peak rates were expected on Saturday March 
13th. The current radiant position lies at 17:08 (257) -50. This position lies in central Ara, four degrees west of the third 
magnitude star Alpha Arae. 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 eight 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 twelve 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 reduced due to lunar 
glare.

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

Antihelion (ANT)) - 12:52 (193) -06   Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.

Zeta Serpentids (ZSR)) - 17:04 (256) -04     Velocity - 64km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

Gamma Normids (GNO) - 17:08 (257) -50    Velocity - 56km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: 
http://www.amsmeteors.org/showers.html#X2010

Clear Skies!
Robert Lunsford
American Meteor Society