(meteorobs) Meteor Activity Outlook for March 21-27, 2009

[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 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.

Antihelion (ANT) - 12:56 (194) -06   Velocity - 30km/sec.
Hourly Rates - Northern Hemisphere - 2   Southern Hemisphere - 2

Gamma Normids (GNO)  16:28 (247) -49   Velocity - 56km/sec.
Hourly Rates - 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#X2009

Clear Skies!
Robert Lunsford
American Meteor Society