(meteorobs) Meteor Activity Outlook for March 13-19, 2010
Robert Lunsford
lunro.imo.usa at cox.net
Thu Mar 11 12:49:18 EST 2010
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 new phase on Monday March 15th. At this time the moon lies near the sun and cannot be seen
at night. Later in the period moon enters the evening sky but sets soon after the end of evening twilight. 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.
The radiant positions and rates listed below are exact for Saturday night/Sunday morning March 13/14. 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 12:24 (186) -04. This area of the sky lies in western Virgo, three degrees
southwest 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 eastern Leo, Sextans, Crater, 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.
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 only one per hour, even with the radiant located high in the sky. Peak rates are expected on Saturday
March 13th. The current radiant position lies at 16:32 (248) -51. This position lies in eastern Norma, two degrees southeast 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 eight 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 eleven 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.
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)) - 12:24 (186) -04 Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr.
Gamma Normids (GNO) - 16:32 (248) -51 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
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