(meteorobs) Meteor Activity Outlook for March 9-15, 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 last quarter phase on Monday March
12. At this time the moon will rise near 0100 local daylight time and will
hamper observing the remainder of the morning. 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 seven for northern observers
and nine 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. Rates are reduced during the morning hours due to
moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning March 10/11. 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 Delta Leonids (DLE) are now near the end of their active period for
2007. Rates seen from anywhere would now be less than one per hour from a
radiant now centered at 12:04 (181) +12. This area of the sky is centered in
northwestern Virgo, four degrees southeast of the second magnitude star
Denebola (Beta Leonis). This radiant is best placed near 0200 Local Daylight
Time (LDT) when it lies on the meridian and is highest in the sky. With an
entry velocity of 23 km/sec., the average Delta Leonid meteor would be of
slow speed.

The Antihelion (ANT) radiant is now centered at 12:12 (183) -02. This area
of the sky is centered in western Virgo, two degrees west of the fourth
magnitude star Eta 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
15:45 (236) -50. This position lies in a remote area of western Norma, eight
degrees northeast of the third magnitude star Iota Lupi. Predicted ZHR's are
near four at maximum activity. Actual rates as seen from the southern
hemisphere would be 1-2 per hour. 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 no matter your location.
One would expect to see perhaps five 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 four per hour. Sporadic
rates seen from the southern hemisphere are also falling toward a mid-month
low. One would expect to see perhaps six random meteors during the last hour
before dawn 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 five by midnight. Morning rates are reduced due to moonlight.

Delta Leonids (DLE)  12:04 (181) +12
Northern Hemisphere - >1   Southern Hemisphere - >1

Antihelion (ANT) - 12:12 (183) -02
Northern Hemisphere - 2   Southern Hemisphere - 2

Gamma Normids (GNO)  15:45 (236) -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