(meteorobs) Meteor Activity Outlook for February 14-20, 2009

[Robert Lunsford]

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 last quarter phase on Monday February
16th. At this time the moon lies ninety degrees west of the sun and will set
rise midnight local standard time (LST). These lunar conditions are
favorable for the slow evening hours. As the week progresses the moon wanes
and rises later each morning, creating an improving situation for the 
morning
observer. 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 ten 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.
Morning rates are reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning February 14/15. 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 10:36 (159) +07. This
area of the sky lies in southern Leo, seven degrees southeast 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 southern Leo or
Sextans 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 Delta Leonids (DLE) reach a ZHR of one on February 15. Visual rates will
be less than one at this time, no matter your location. The radiant is now
located at 10:36 (159)+19. This area of the sky lies in central Leo, two
degrees east of the second magnitude star Algeiba (Gamma 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 Alpha Centaurids (ACE) are active from a radiant located at 14:40
(220) -62. This area of the sky is located in southeastern Centaurus, just
south of the brilliant zero magnitude star Rigel Kentaurus (Alpha Centauri).
As seen from the southern hemisphere, current rates would be 1-2 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 28
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 seven 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 eight 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. Morning rates are reduced due to
moonlight.

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) - 10:36 (159) +07   Velocity - 30km/sec.
Hourly Rates - Northern Hemisphere - 2   Southern Hemisphere - 2

Delta Leonids (DLE) - 10:36 (159) +19   Velocity - 23km/sec.
Hourly Rates - Northern Hemisphere - <1   Southern Hemisphere - <1

Alpha Centaurids (ACE)  14:40 (220) -62   Velocity - 56km/sec.
Hourly Rates - Northern Hemisphere - <1   Southern Hemisphere - 2

*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