(meteorobs) Meteor Activity Outlook for February 11-17, 2005

[Robert Lunsford]

This upcoming period will see the moon reaching its first quarter phase on
Wednesday February 16.  At this time the moon will set near midnight,
leaving the predawn hours free of interfering moonlight. The estimated total
hourly rates for evening observers this week should be near two for those in
the Northern Hemisphere and three for those observers south of the equator.
Evening rates are reduced due to moonlight. For morning observers the
estimated total hourly rates should be near ten for those located in the
Northern Hemisphere and eighteen for those 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning February 12/13. 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 Velids (DVE) is a shower listed among radiants of the Dutch Meteor
Society. The date of maximum activity is February 14 with a predicted ZHR of
one. With such low activity care must be taken to exclude any sporadic
activity from the Delta Velid count. The radiant currently lies at 08:40
(130) -52. This position lies in western Vela, two degrees north of the
second magnitude star Delta Velorum. This radiant is only seen well from the
northern equatorial regions southward. The area of the sky is also best
placed near midnight local standard time. At 35 km/sec. the Delta Velids
produce meteors of average velocity.

The Alpha Hydrids (AHY) is another shower listed among radiants of the Dutch
Meteor Society. The date of maximum activity was January 14 with a predicted
ZHR of two. Current rates would be far 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 10:16 (154) -20.
This position lies in western Hydra, three degrees southwest of the faint
star Mu Hydrae. This radiant is seen equally well from both hemispheres. The
area of the sky is also best placed near 0200 local standard time. At 44
km/sec. the Alpha Hydrids produce meteors of average velocity.

The Anthelion radiant is now centered at 10:32 (158) +08. This area of the
sky is located in southwestern Leo, very close to the faint star Rho Leonis.
Since this radiant is large and diffuse, any slow to medium speed meteor
from northeastern northwestern Hydra, western Leo or Cancer could be a
candidate for this shower. The center of this area is best placed near 0100
local standard time when it lies on the meridian and is highest in the sky.
At this time expect to see two shower members per hour no matter your
location.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and metallic
debris whose density is much greater than material produced by comets. There
is also the possibility that some of this activity may be caused by the
"Jupiter family of comets", comets which have been altered by Jupiter's
gravity into much shorter orbits. This material collides with the earth on
the inbound portion of its orbit, before its closest approach to the sun.
Therefore we best see them just after midnight when we are facing the
direction from which this activity appears. The antihelion source is active
all year from an area of the sky nearly opposite that of the sun. The center
of this source will move approximately one degree eastward per day and
travels through many different constellations over the course of a year. It
may make sense to list these meteors as anthelions or "ANT" but a majority
of meteor organizations prefer that you list them from the constellation in
which the radiant is currently located or the constellation where the shower
reaches maximum activity. Observers who send their reports to the
International Meteor Organization (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. The date
of maximum activity is February 14 with a predicted ZHR of two. The radiant
lies at 11:44 (176) -56. This position is in western Centaurus, four degrees
southeast of the fourth magnitude star Pi Centauri. 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 0300 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 is February 14 with a predicted ZHR
of four. The radiant lies at 13:56 (209) -41. This position is in central
Centaurus, close to the third magnitude star Nu 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. These meteors are impressive as
they shoot upwards from the deep southern skies. Although swift, they can
last several seconds. 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 Centaurids (ACE) are the strongest of the radiants that are active
in Centaurus during late January and throughout the month of February. The
date of maximum activity was February 8 with a predicted ZHR of seven.
Current rates should be 2-3 per hour. The radiant lies at 14:28 (217) -61.
This position is in southeastern Centaurus, lying directly between the
brilliant stars Rigel Kentaurus (Alpha Centauri) and Hadar (Beta 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.

Possible activity in Bootes-Corona Borealis-Serpens Caput? There have been
reports of activity in and around this area in late January and early
February. Veteran observer George Gliba was the first to notice this
activity during the mid 90's. Intensified video studies by t he IMO in 2000
revealed two radiants; one in Serpens Caput and another located in Corona
Borealis during the first week of February. Observers are urged to keep a
look out for this activity now through mid-February. The two IMO radiants
are located at 15:32 (233) +30 and 15:44 (236) +13. The northern radiant is
located within the "crown" close to the star Beta Coronae Borealis. The more
southern radiant is located near the "head" of Serpens two degrees south of
Beta Serpentis. Another area of possible activity would lie in eastern
Bootes between Arcturus and Xi Bootis. This area of the sky is too low until
0200 local standard time.

Any suspected shower members would appear to move slowly if seen near the
radiant or near the horizon. Those seen high in the sky and far from the
radiant will appear to be swift. Meteors seen near the radiant would also be
short. If you are facing the radiants and see a long meteor close to the
radiant(s) then that meteors is sporadic or belongs to another shower.
Plotting, photographic and video observations are of prime importance to try
to help us determine shower association. Your efforts in trying to help us
verify this activity and its exact radiant would be extremely appreciated.

The Sporadic rates for the Northern Hemisphere are now past their annual
peak. One would expect to see perhaps eight 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 ten random meteors per hour during the
late morning hours and three per hour during the evening. Evening rates are
reduced due to moonlight.


Delta Velids(DVE)   Radiant Position  = 08:40 (130)  -52
Hourly Rate = 0  N. Hemisphere, <1  S. Hemisphere

Alpha Hydrids (AHY)   Radiant Position  = 10:16 (154)  -20
Hourly Rate = <1  N. Hemisphere, <1  S. Hemisphere

Anthelion        Radiant Position  = 10:32  (158) +08
Hourly Rate = 2  N. Hemisphere, 2  S. Hemisphere

Omicron Centaurids (OCE)   Radiant Position  = 11:44 (176)  -56
Hourly Rate = 0  N. Hemisphere, 1  S. Hemisphere

Theta Centaurids (TCE)   Radiant Position  = 13:56 (209)  -41
Hourly Rate = <1  N. Hemisphere, 2  S. Hemisphere

Alpha Centaurids (ACE)   Radiant Position  = 14:28 (217)  -61
Hourly Rate = 0  N. Hemisphere, 2  S. Hemisphere

Clear Skies!
Robert Lunsford
American Meteor Society