(meteorobs) Meteor Activity Outlook for February 17-23, 2006

[Robert Lunsford]

At this time of year most of the meteor shower activity is produced by weak
radiants located in the deep southern portion of the sky.  A majority of
these radiants produce rates much less than that of the sporadic background
(random meteors) therefore the possibility of chance alignments is high,
even for observers located in the Southern Hemisphere, where these radiants
rise higher into the sky. These showers are often not included on lists
intended for visual observers. They are presented here to offer targets for
those observers who carefully plot the meteor activity they see and those
who use other methods of meteor observing such as telescopic, photographic,
and video. I would advise a majority visual observers to concentrate on
reporting the activity of showers rated at least class III or higher. These
showers offer the best opportunity to see activity other than that produced
by the sporadic background.

The moon reaches its last quarter phase on Tuesday February 21. At this time
the moon will rise near midnight local standard time and will remain in the
sky the remainder of the morning. This weekend the waning gibbous moon will
be a serious hindrance to visual observers as the bright glare of the moon
will obscure all but the brighter meteors. The gibbous moon will rise during
the late evening hours and will also remain in the sky for the remainder of
the night. Visual observers can best cope with this bright moonlight by
facing away from the moon when observing. Transparent skies would also help
you view more activity compared to hazy skies, which scatter much more
moonlight. The estimated total hourly rates for evening observers this week
should be near two no matter your location. For morning observers the
estimated total hourly rates should be near eight for Northern Hemisphere
observers and nine for those located in the Southern Hemisphere. 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 listed below are exact for Saturday night/Sunday
morning February 18/19. 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. 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.

These are the showers that may be observed this week:

The Delta Leonids (DLE) peak on February 24 with a ZHR of two. With the
bright moon, current rates would be less than one per hour. The radiant is
located at 10:52 (163) +18. This area of the sky is located in central Leo;
midway between the bright stars Gamma and Theta Leonis. This radiant lies
fairly close to the Eclipticid radiant so care must be taken when tracing
activity back to this portion of the sky. The best time to view this
activity is near 0100 local time, when the radiant lies on the meridian and
at its highest point above the horizon. With an entry velocity of 23
kilometers per second, these meteors will appear to move slowly.

The Eclipticid (ECL) radiant is now centered at 11:24 (171) +06. This area
of the sky is located in southeastern Leo, one degree southeast of the
fourth magnitude star Theta Leonis. This radiant is best placed near 0100
local standard time when it lies on the meridian and is highest in the sky.
Rates should be near two per hour no matter your location. With an entry
velocity of 30 km/sec., the average Eclipticid meteor would be of
medium-slow speed. This radiant is a good source of fireballs, more so as we
progress through the winter months. Those who send reports to the I.M.O.
should label these meteors as Virginids (VIR).

The Omicron Centaurids (OCE) are one of several radiants that are active in
Centaurus during late January and throughout the month of February. This is
the weakest of the three radiants now active in Centaurus. The date of
maximum activity was February 14 with a predicted ZHR of two. Actual rates
would be less than one shower member per hour, no matter your location. The
radiant lies at 12:08 (182) -58. This position lies in northwestern Crux,
seven degrees west of the second magnitude star Gacrux (Gamma Crucis). Due
to the southern declination this shower is not well seen north of the
northern tropical regions. This area of the sky is best placed near 0200
local standard time when it lies highest in the sky. At 51 km/sec. the
Omicron Centaurids produce meteors of medium-swift velocity.

The Theta Centaurids (TCE) is the most northerly of several radiants that
are active in Centaurus during late January and throughout the month of
February. The date of maximum activity was February 14 with a predicted ZHR
of four. Current rates would be near one per hour for areas where the
radiant rises high into the sky. The radiant lies at 14:24 (216) -43. This
position lies in western Lupus, very close to the area occupied by the third
magnitude star Eta Centauri. This shower is not well seen north of the
northern tropical regions. It is possible to see activity from the latitude
of San Diego, CA as I have witnessed several of these meteors during my
winter observations. This area of the sky is best placed near 0400 local
standard time when it lies highest in the sky. At 60 km/sec. the Theta
Centaurids produce meteors of swift velocity.

The Alpha Centaurids (ACE) are now near the end of their activity period.
Current rates would be less than one per hour. The date of maximum activity
was February 8 with a predicted ZHR of seven. The radiant lies at 14:56
(224) -63. This position is in central Circinus, six degrees southeast of
the brilliant zero magnitude star Rigel Kentaurus (Alpha Centauri). Due to
the southern declination this shower is not well seen north of the northern
equatorial regions. This area of the sky is also best placed near 0500 local
standard time when it lies highest in the sky. At 56 km/sec. the Alpha
Centaurids produce meteors of swift velocity.

The Sporadic rates for the Northern Hemisphere are now past their annual
peak. One would expect to see perhaps six random meteors per hour during the
last hours before dawn from rural observing sites. During the evening hours
perhaps two random meteors can be seen per hour. Sporadic rates seen from
the Southern Hemisphere are also decreasing toward a secondary minimum in
March. One would see approximately six random meteors per hour during the
late morning hours and two per hour during the evening. Morning rates are
reduced due to moonlight.

Delta Leonids (DLE)    10:52 (163) +18   Class II
Hourly Rate = N. Hemisphere >1 - S. Hemisphere >1

Eclipticid (ECL)    11:24 (171) +06   Class II
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 2

Omicron Centaurids (OCE)    12:08 (182) -58   Class IV
Hourly Rate = N. Hemisphere >1 - S. Hemisphere >1

Theta Centaurids (TCE)     14:24 (216) -43   Class IV
Hourly Rate = N. Hemisphere >1 - S. Hemisphere 1

Alpha Centaurids (ACR)    14 :56 (224) -63   Class II
Hourly Rate = N. Hemisphere 0 - S. 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#X2006

Clear Skies!
Robert Lunsford
American Meteor Society