(meteorobs) Meteor Activity Outlook for March 16-22, 2007

[Robert Lunsford]

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.

Antihelion (ANT) - 12:40 (190) -05
Northern Hemisphere - 2   Southern Hemisphere - 2

Gamma Normids (GNO)  16:12 (243) -50
Northern Hemisphere - >1   Southern Hemisphere - 1

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2006

Clear Skies!
Robert Lunsford
American Meteor Society