(meteorobs) Meteor Activity Outlook for December 30, 2005-January 5, 2006

[Robert Lunsford]

As we age and hopefully grow wiser, we all make some attempt to change and
adapt. One portion of my personal adaptation is to try and stay current in
the rapidly changing field of astronomy so I can inform others to the best
of my ability. I'm the sort of person who prefers to classify everything.
Relating to meteors, I did everything possible to avoid placing meteors into
that purgatory known as the "sporadic bin". Therefore when I started this
weekly column, I introduced terms such as apex, antiapex, and anthelion,
hoping to save some meteors from that sporadic abyss. After years of study I
will now admit that the three sources previously mentioned do not provide
enough activity to warrant separate designations. Therefore, beginning in
2006, I am asking that observers simply drop these designations and list any
such meteors as sporadic. But fear not you fans anthelion activity! We are
bringing back some old favorites such as the Virginids and Sagittarids, but
under a new guise suggested by the International Meteor Organization. No
longer will the Virginids radiant from Leo or the Sagittarids come from
Libra. With this edition we introduce a new designation called the
Eclipticids (ECL). These are true showers attributed to comets and asteroids
that deserve study and observation. The 2006 I.M.O. calendar will list these
showers with their common names and abbreviations. Not until 2007 will the
I.M.O. switch designations for these showers. Therefore I will list the
equivalent I.M.O. designation this year so that their observers know what
shower I am discussing. I feel this is a positive step and one that will aid
in helping observers properly classify the activity they witness.  Now on to
the activity for next week!

The moon reaches its new phase on Saturday December 31. At this time the
moon will rise and set with the sun and will not interfere with observing at
all. Later in this period, the waxing crescent moon will emerge in the
evening sky but will set soon after the end of evening twilight and will not
cause any problems. The estimated total hourly rates for evening observers
this week should be near four for Northern Hemisphere observers and three
for those located in the Southern Hemisphere. For morning observers the
estimated total hourly rates should be near thirteen for Northern Hemisphere
observers and eight 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.

The radiant positions listed below are exact for Saturday night/Sunday
morning December 31/January 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. 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 07:28 (112) +22. This area
of the sky is located in eastern Gemini, seven degrees southwest of the
first magnitude star Pollux (Beta Geminorum). 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 from the Northern Hemisphere and
one 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 Gamma Velids (GVE) are a class IV shower (best left for study by
observers who use video and photographic observations). This is the first of
many weak southern showers active during January and February. The Gamma
Velids are listed among the radiants of the Dutch Meteor Society and reach
maximum activity on January 5. Visual rates would be low, most likely less
than one shower member per hour. The radiant is currently located near 08:16
(124) -47. This position lies in western Vela, only one degree northeast of
the second magnitude star Gamma Velorum. The radiant lies highest in the sky
between 0100 and 0200. This shower is not visible north of latitude 45
north. At 35 km/sec. the Gamma Velids produce meteors of average velocity.

The Coma Berenicids (COM) reached maximum activity on December 19, when the
ZHR reaches five. Current rates would be 1-2 shower members per hour at
best. The radiant is currently located at 12:24 (186) +20, which places it
in central Coma Berenicids, ten degrees northeast of the second magnitude
star Denebola (Beta Leonis). This radiant is best placed for viewing just
before dawn, when it lies highest above the horizon. At 65 km/sec. the Coma
Berenicids produce mostly swift meteors with the brighter shower members
leaving persistent trains.

The Quadrantids (QUA) reach maximum activity on January 3 near 1820
Universal Time. This corresponds to 1320 EST and 1020 PST, both during
daylight hours. The western Pacific area is favored for the 2006 display,
but on the morning of January 4, local time. The radiant is located at 15:20
(230) +49. This position lies in a sparse area of northern Bootes, ten
degrees south of the third magnitude star Iota Draconis. Rates can exceed
one hundred shower members per hour if the radiant is high in a dark sky at
the time of maximum activity. Most observers will see much less than this,
probably closer to 25 per hour. While some activity may be seen during the
evening hours from high northern latitude areas, the prime hours lie in the
late morning hours when the radiant rises high into the northeastern sky.
This shower is not well seen south of the equator as the radiant does not
rise sufficiently high into the sky before the start of morning twilight. At
41 km/sec. the Quadrantids produce meteors of average velocity with a few
persistent trains.

The Sporadic rates for the Northern Hemisphere are now just 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 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 six random meteors per hour during the
late morning hours and two per hour during the evening.

Possible Outburst?- Observers in South America should be on the alert near
0620 Universal Time on January 2, when the Earth is predicted to pass
through a trail of debris produced by C1969T Tago-Sato-Kosaka. The predicted
radiant lies at 15:24 (231) -57. This position lies near the borders of the
constellations of Norma, Circinus, and Lupus, five degrees southeast of the
third magnitude star Zeta Lupi. It is impossible to predict the exact
intensity of this display, or even if it will occur. The circumstances are
unusually favorable though as the Earth passes only 26,000 miles from the
predicted center of this debris. Now the question is, just how richly
populated is this trail with the comet now 37 years past perihelion?
Information provided by the International Meteor Organization's Alastair
McBeath, in their 2006 Meteor Shower Calendar.

Eclipticid     07:28 (112) +22
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 1

Gamma Velids (GVE)  08:16 (124) -47
Hourly Rate = N. Hemisphere 0 - S. Hemisphere >1

Coma Berenicids (COM)  12:24 (186) +20
Hourly Rate = N. Hemisphere 2 - S. Hemisphere 1

Quadrantids (QUA)  15:20 (230) +49
Hourly Rate = N. Hemisphere 1 - S. Hemisphere 0

Clear Skies!
Robert Lunsford
American Meteor Society