(meteorobs) Meteor Activity Outlook for March 7-13, 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 full phase on Wednesday March 11th.
At this time the moon lies 180 degrees opposite the sun and is in the sky
all night long. This weekend a small window of opportunity exists between
moonset and the start of morning twilight, when observers can view under
dark, moonless conditions. The estimated total hourly rates for evening
observers this week is near one as seen from the northern hemisphere and two
for those situated south of the equator. For morning observers the estimated
total hourly rates should be near five for those located in the mid-northern
hemisphere (45 N) and six 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 reduced during this period due to lunar interference.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning March 8. 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 weak Delta Leonids (DLE) reached maximum on Wednesday February 25th. The
activity for this shower is nearly over and one would be lucky to see one
shower member per night at this time. The radiant is now located at 11:56
(179) +12. This area of the sky lies in eastern Leo, two degrees southeast
of the second magnitude star Denebola (Beta Leonis). This radiant is best
placed near 0100 local standard time 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 wide Antihelion (ANT) radiant is now centered at 12:00 (180) -01. This
area of the sky lies in western Virgo, five degrees west of the fourth
magnitude star Eta Virginis. This radiant is also best placed near 0100 LST.
Due to the large size of this radiant, any meteor radiating from
southeastern Leo or western Virgo could be a candidate for this shower.
Rates at this time should be near one 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 active from a radiant located at 15:32
(233) -50. This area of the sky is located on the Lupus/Norma border, three
degrees northeast of the third magnitude star Zeta Lupi. With the maximum
not occurring until March 13th, current visual rates would still be less
than one shower member per hour, no matter your location. These meteors are
best seen between 0400 and 0500 local standard 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 four 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 five 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. Sporadic rates are reduced 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.

Delta Leonids (DLE) - 11:56 (179) +12   Velocity - 23km/sec.
Hourly Rates - Northern Hemisphere - <1   Southern Hemisphere - <1

Antihelion (ANT) - 12:00 (180) -01   Velocity - 30km/sec.
Hourly Rates - Northern Hemisphere - 1   Southern Hemisphere - 1

Gamma Normids (GNO)  15:32 (233) -50   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