(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