(meteorobs) Meteor Activity Outlook for February 1-7, 2008

[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 2-3 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 its new phase on Thursday February 7th.
At this time the moon will be located near the sun in the sky and not
visible at night. This weekend the waning crescent moon will rise during the
late morning hours and will not interfere with observing. The estimated
total hourly rates for evening observers this week is near two no matter
your location. For morning observers the estimated total hourly rates should
be near fifteen for those located in the mid-northern hemisphere (45 N) and
eighteen for those viewing from the mid-southern hemisphere (45 S). 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 February 2/3. 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 09:48 (147) +12. This
area of the sky lies in western Leo, four degrees northwest of the bright
star Regulus (alpha Leonis). This radiant is best placed near 0100 local
standard time when it lies on the meridian and is highest in the sky.
Actually any meteor from eastern Cancer or western Leo could be a candidate
for this shower. Rates at this time should be near three per hour as seen
from the northern hemisphere and two per hour for observers located south of
the equator. With an entry velocity of 30 km/sec., the average Antihelion
meteor would be of medium-slow speed.

Studies by Sirko Molau of the IMO's video database has revealed activity on
the Sextans-Hydra border during the first week of February. Maximum activity
occurs On February 2nd when the radiant is located at 158 (10:32) -11. This
area of the sky is located in southern Sextans, very close to the Hydra
border. The nearest bright star is second magnitude Alphard, (alpha Hydrae)
which lies fifteen degrees to the west. Although low rates are expected from
this source, visual observers are encouraged to monitor this source during
this period. These meteors are best seen near 0200 local standard time when
the radiant lies on the meridian and is highest above the horizon. With a
radiant located close to the celestial equator these meteors would be
visible over virtually the entire Earth. At 42 km/sec. these meteors would
produce meteors of medium velocity.

The Alpha Centaurids (ACE) are active from a radiant located at 13:44
(206) -58. This area of the sky is located in southeastern Centaurus, four
degrees northwest of the brilliant star Hadar (beta Centauri). Current rates
would be near one shower member 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.

Sporadic rates are now slowly falling no matter your location. One would
expect to see approximately twelve random meteors during the last hour
before dawn from rural observing sites in the northern hemisphere and
fifteen from the southern hemisphere. During the first dark hour after the
end of evening twilight, perhaps two random meteors can be seen per hour, no
matter your location.

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) - 09:48 (147) +12   Velocity - 30km/sec.
Northern Hemisphere - 3   Southern Hemisphere - 2

February Sextantids (Non-IMO Shower)  10:32 (158) -11
Velocity - 42 km/sec.
Northern Hemisphere - >1   Southern Hemisphere - >1

Alpha Centaurids (ACE)  13:44 (206) -58   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