(meteorobs) Meteor Activity Outlook for January 31-February 6, 2009
Robert Lunsford
lunro.imo.usa at cox.net
Fri Jan 30 12:57:49 EST 2009
February is the only month of the year that sees a fall in rates in both
hemispheres. As seen from the northern hemisphere, sporadic rates continue
the fall that began in January. This will continue until June when rates
reach their nadir. After a brief peak of activity in January, sporadic rates
in the southern hemisphere also slide downward until March. Shower activity
is low this month but decidedly more interesting in the southern hemisphere.
During February there are several sources of activity in the southern
morning sky. Most notable is the Alpha Centaurids, which are active during
the entire month of February. Other sources are scattered from Carina
through Puppis, Vela, and on into Centaurus and Lupus. None of these even
rate as a minor shower but together, along with the Alpha Centaurids, create
some interesting viewing during the summer nights south of the equator. Only
a trace of this activity can be seen from the northern tropics. The
Antihelion radiant remains north of the celestial equator and produces a
modest 1-2 meteors per hour from Leo. The weak Delta Leonids become active
at mid-month but are few and far between, even at maximum activity.
During this period the moon reaches it first quarter phase on Monday
February 2nd. At this time the moon lies ninety degrees east of the sun and
will set near midnight local standard time (LST). Late next week the waxing
gibbous moon begins to interfere with morning observations as it sets later
and later each morning. 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 fourteen for those located in
the mid-northern hemisphere (45 N) and twenty 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.
The radiant positions and rates listed below are exact for Saturday
night/Sunday morning January 31/February 1. 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 09:40 (145) +13. This
area of the sky lies in western Leo, five degrees northwest of the first
magnitude Regulus (Alpha Leonis). This radiant is best placed near 0100 LST,
when it lies on the meridian and is located highest in the sky. Due to the
large size of this radiant, any meteor radiating from eastern Cancer or
western Leo 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 Alpha Centaurids (ACE) are active from a radiant located at 13:32
(203) -58. This area of the sky is located in southeastern Centaurus, four
degrees southwest of the second magnitude star Epsilon Centauri. As seen
from the southern hemisphere, current rates would be 2-3 per hour. These
meteors are best seen near 0500 local standard time when the radiant lies
highest above the horizon. This shower is not visible north of 32 degrees
north latitude and also poorly seen in the northern tropics. The southern
hemisphere offers a much better view of this activity as the radiant lies
much higher in the southern sky. Those located at high southern latitudes
will actually encounter morning twilight before the radiant reaches
culmination. At 56 km/sec. the Alpha Centaurids will usually produce meteors
of swift velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see
approximately twelve 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 fifteen 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.
The list 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) - 09:40 (145) +13 Velocity - 30km/sec.
Hourly Rates - Northern Hemisphere - 2 Southern Hemisphere - 2
Alpha Centaurids (ACE) 13:32 (203) -58 Velocity - 56km/sec.
Hourly Rates - Northern Hemisphere - >1 Southern Hemisphere - 3
*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
More information about the Meteorobs
mailing list