(meteorobs) Meteor Activity Outlook for January 20-26, 2006

[Robert Lunsford]

The moon reaches its last quarter phase on Saturday January 22. At this
time the moon will rise near midnight local standard time and will remain in
the morning sky well past sunrise. Later in this period, the waning crescent
moon will rise later in the morning allowing more time to observe under
totally dark conditions. The estimated total hourly rates for evening
observers this week should be near three for Northern Hemisphere observers
and three for those located in the Southern Hemisphere. For morning
observers the estimated total hourly rates should be near nine for
Northern Hemisphere observers and ten 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 in both hemispheres are reduced due to moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning January 21/22. 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 Eclipticid (ECL) radiant is now centered at 08:48 (132) +19. This area
of the sky is located in central Cancer, very close to the fourth magnitude
star Delta Cancri. 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
three per hour from the Northern Hemisphere and two per hour for observers
south of the equator. With an entry velocity of 28 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 Delta Cancrids
(DCA).

The Alpha Hydrids (AHY) are a class IV shower (best left for study by
observers who use video and photographic observations) shower listed among
the radiants of the Dutch Meteor Society. The date of maximum activity is
January 14 with a predicted ZHR of two. Current rates would be most likely
less than one shower member per hour. With such low activity care must be
taken to exclude any sporadic activity from the Alpha Hydrid count. The
radiant currently lies at 09:16 (139) -13. This position lies in western
Hydra, five degrees southwest of the second magnitude star Alphard (Alpha
Hydrae). This radiant is seen equally well from both hemispheres. The area
of the sky is also best placed on the meridian near 0200 local standard
time. At 44 km/sec. the Alpha Hydrids produce meteors of average velocity.

The Theta Centaurids (TCE) are the first of several radiants that are active
in Centaurus during late January and throughout the month of February. The
date of maximum activity is February 14 with a predicted ZHR of four.
Current ZHR's would be near one. The radiant lies at 12:20 (185) -31. This
position is in a remote area of eastern Hydra, directly south of the
conspicuous constellation of Corvus . 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 0500
local standard time when it lies highest in the sky. At 60 km/sec. the Theta
Centaurids produce meteors of swift velocity.

The Alpha Crucids (ACR) are another class IV shower listed among the
radiants of the Dutch Meteor Society. The date of maximum activity is
January 15 with a predicted ZHR of three. The activity period is nearly
over so the odds of seeing a member of this shower is remote. Like the
previous weak showers, care must be taken to exclude any sporadic
activity from the Alpha Crucid count. The radiant currently lies at 13:12
(200) -66. This position lies in northern Musca near the point occupied
by the faint star Theta Muscae. Due to the far southern declination this
shower is not seen north of the northern equatorial regions. The area of
the sky is also best placed just before dawn when it lies highest in the
sky. At 50 km/sec. the Alpha Crucids produce meteors of medium swift
velocity.

The Sporadic rates for the Northern Hemisphere are now just 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 three random meteors can be seen per hour. Sporadic
rates seen from the Southern Hemisphere are increasing toward a peak this
month. One would see approximately eight random meteors per hour during the
late morning hours and three per hour during the evening.Morning rates in
both hemispheres are reduced due to moonlight.

Eclipticid (ECL)    08:48 (132) +19   Class II
Hourly Rate = N. Hemisphere 3 - S. Hemisphere 2

Alpha Hydrids (AHY)    09:16 (139) -13   Class IV
Hourly Rate = N. Hemisphere >1 - S. Hemisphere >1

Theta Centaurids (TCE)     12:20 (185) -31    Class IV
Hourly Rate = N. Hemisphere 0 - S. Hemisphere >1

Alpha Crucids (ACR)   13:12 (200) -66    Class IV
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