(meteorobs) Meteor Activity Outlook for March 14-20, 2008

[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 fist 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 first quarter phase on Friday March
14th. At this time the moon will be located 90 degrees east of the sun and
will set near 0100 Local Daylight Time or midnight Local Standard Time.
Toward the end of this period the moon will be in the sky most of the night
limiting dark skies to a short period just before dawn. As seen from the
mid-northern hemisphere (45 N) the estimated total hourly rates during the
evening observers would be two. For morning observers the estimated total
hourly rates should be near eight. For those located in the mid-southern
hemisphere (45 S) morning rates would be near fifteen and evening rates near
two. 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. Evening rates are
reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning March 15/16. 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 12:32 (188) -04. This
area of the sky lies in western Virgo, three degrees southwest of the third
magnitude star Porrima (Gamma Virginis). This radiant is best placed near
0200 LDT time (0100 LST) when it lies on the meridian and is highest in the
sky. Actually any meteor from western Virgo, northern Corvus, or
northeastern Crater 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) are active from a radiant located at 16:04
(241) -50. This area of the sky is located in central Norma, five degrees
west of the fourth magnitude star Gamma Normae. This shower peaked on the
13th so rates are now slowly falling to near 1-2 per hour as seen from deep
southern latitudes. These meteors are best seen between 0500 and 0600 LDT
(0400 and 0500 LST), 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 in the most of the northern
hemisphere. An occasional member may be seen from the northern tropics. At
56 km/sec. the Gamma Normids will usually produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) the Sporadic rates are still
slowly falling. One would expect to see approximately eight random meteors
during the last hour before dawn from rural observing sites and two per hour
during the evening hours. As seen from the mid-southern hemisphere (45S)
morning rates would be near 12 per hour as seen from rural observing sites
and two per hour during the evening hours. Evening rates are reduced due to
moonlight.

The table below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning.

Antihelion (ANT)  12:32 (188) -04   Velocity - 30 km/sec.
Northern Hemisphere - 2   Southern Hemisphere - 2

Gamma Normids (GNO) 16:04 (241) -50   Velocity - 56 km/sec
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#X2008

Clear Skies!
Robert Lunsford
American Meteor Society