(meteorobs) Meteor Activity Outlook for December 29 2006 - January 4, 2007

[Robert Lunsford]

January sees a peak of sporadic activity for the southern hemisphere while
rates seen north of the equator begin a steady downward turn that continues
throughout the first half of the year. The sporadic activity is good for
both hemispheres, but not as good as it was for northern observers in
December. Once the Quadrantids have passed the shower activity for January
is very quiet.

This week the moon reaches its full phase on Wednesday January 3. At this
time the moon will be present in the sky all night long and will interfere
with all observing attempts. This weekend the waxing gibbous moon will set a
few hours before dawn allowing a small window of opportunity to view
activity in dark skies. The estimated total hourly rates for evening
observers this week is near three for those located north of the equator and
three for observers south of the equator. For morning observers the
estimated total hourly rates should be near ten for northern observers and
six for those located south of the equator. 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. Rates are reduced due to the intense moonlight.

The radiant positions listed below are exact for Saturday night/Sunday
morning December 30/31. 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. This method 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.

These showers are expected to be active this week:

The Antihelion (ANT) radiant is now centered at 07:28 (112) +21. This area
of the sky lies in central Gemini, two degrees east of the third magnitude
star Delta Geminorum. This radiant is best placed near 0100 local standard
time when it lies on the meridian and is highest in the sky. Rates at this
time should be near two per hour as seen from the northern hemisphere and
one per hour for observers located south of the equator. With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

Sirko Molau's study of video radiants has revealed activity during the
period January 3-9, from an area in western Hydra. Maximum occurs on January
4 with the radiant located at 8:32 (128) -13. This position lies fifteen
degrees southwest of the second magnitude star Alphard (Alpha Hydrae). This
radiant is best placed near 0200 LST when it lies highest in the sky. It
appears that four percent of the total sporadic activity for the night is
related to this radiant. This would equate to only 1-2 shower members per
hour at best. With a bright moon in the sky, seeing any activity from this
radiant would be remote. At 39km/sec., the average meteor from this radiant
would be of medium velocity.

Sirko Molau's study of video radiants has also revealed activity during the
period January 1-5, from an area in western Leo. Maximum occurs on January 3
with the radiant located at 9:44 (146) +25. This position lies very close to
the third magnitude star (Epsilon Leonis). This radiant is best placed near
0300 LST when it lies highest in the sky. It appears that five percent of
the total sporadic activity for the night is related to this radiant. This
would equate to only 1-2 shower members per hour at best. With a bright moon
in the sky, seeing any activity from this radiant would again be remote. At
55km/sec., the average meteor from this radiant would be swift.

The Coma Berenicids (COM) peaked near December 20 with an average ZHR of
five. Rates have now fallen to 2-3 per hour as seen from the northern
hemisphere. Bright moonlight will reduce these rates even more. Activity may
be seen from the southern hemisphere, but at a lower rate. The current
location of this radiant is 12:24 (186) +20. This area of the sky is located
in central Coma Berenices border some eight degrees northeast of the second
magnitude star Denebola (Beta Leonis). These meteors are best seen near 0600
local standard time when the radiant lies highest above the horizon. At 5
km/sec. the Coma Berenicids will usually produce meteors of swift velocity.

The Quadrantids (QUA) The Quadrantids will peak near 00:30 Universal Time on
January 4, 2007. This timing favors central Asia where the radiant will be
located highest in a dark sky. For North America this time corresponds to
07:30 PM EST and 04:20 PM PST on the evening of January 3. Some evening
activity may be seen from North America but counts will be low due to the
low altitude of the radiant at this time. The radiant is located at 15:20
(230) +49. This area of the sky lies in northern Bootes in an area southeast
of the handle of the "Big Dipper". This area of the sky is located low in
the northwestern sky at dusk. It reaches it lowest point below the pole star
near 1900 local standard time and then begins its slow ascent into the
northeastern sky. It is best placed during the last hour before dawn when it
lies approximately half-way up in the northeastern sky. This is when most of
the activity will be seen.

Unfortunately the moon will be full on January 3, and will severely limit
the number of meteors that will be seen. The moon will be in the sky all
night and will affect counts no matter the time of night. Due to the
southern declination of the moon, it will not rise too high in the southern
sky, especially for far northern observers. When viewing this display it
would be best to face toward the northern half of the sky. If hills or
lights obscure your northern horizon then switch toward a more easterly
view. Whatever direction you face, be sure to look approximately half-way up
into the sky. Most of the meteor activity occurs in the lower half of the
sky so place the lower portion of your field of view just above the horizon
or trees to see the best activity. Observers in the Southern Hemisphere will
see very little Quadrantid activity as the radiant will not rise
sufficiently in altitude before the onset of morning twilight. All
Quadrantid meteors will trace back to the radiant area in Northern Bootes.
There will be other showers and random activity visible during this period
so not all meteors will be members of the Quadrantid shower. Quadrantid
meteors will appear to travel swiftly through the sky unless they are seen
near the radiant or near the horizon. Quads seen there will move more slowly
as they are moving towards you (if seen near the radiant) or away from you
(if seen near the horizon). It is of great importance is to be warm and
comfortable while viewing these meteors. Running outside for just a quick
peek will not provide any satisfaction.

This shower is named for the obsolete constellation Quadrans Muralis (Murals
Quadrant), which once occupied the area of northern Bootes. Some meteor
organizations refer to this shower as the Bootids. It is thought that this
shower is related to the recently discovered asteroid 2003 EH1. Peter
Jenniskens, who discovered this relationship, states that this object is
most likely an extinct comet nucleus that appears to be the remnant of a
larger object that broke up about 500 years ago. The Earth intersects the
orbit of this object near January 4 each year. The Earth intersects this
orbit at a perpendicular angle which means we quickly move through any
debris produced by this object. ZHR's in excess of one are produced for only
five days centered on the time of maximum activity. This will be the last
opportunity to see a major annual shower until the Lyrids of April.

Sporadic rates have passed the late year plateau for observers located in
the northern hemisphere. One would expect to see perhaps five random meteors
during the last hour before dawn from rural observing sites. During the
first dark hour after the end of evening twilight, perhaps three random
meteors can be seen per hour. Sporadic rates increase as the night
progresses so rates seen near midnight would be near four per hour. Sporadic
rates seen from the southern hemisphere have passed their annual minimum and
are rising again. One would expect to see approximately five random meteors
per hour during the last hour before dawn and three per hour during the
first dark hour after the end of evening twilight. Rates near midnight would
be near four per hour. All rates are reduced due to the intense moonlight.

Antihelion (ANT) - 07:00 (105) +22 30
Northern Hemisphere - 2  Southern Hemisphere  - 1

Alpha Hydrids (AHY)  8:32 (128) -13
Northern Hemisphere - >1  Southern Hemisphere  - >1

Epsilon Leonids (ELE)  9:44 (146) +25 55
Northern Hemisphere - >1  Southern Hemisphere  - >1

Coma Berenicids (COM)  12:24 (186) +20
Northern Hemisphere - 1  Southern Hemisphere  - >1

Quadrantids (QUA)  15:20 (230) +49
Northern Hemisphere - 2  Southern Hemisphere  - 0

*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