Meteor Activity Outlook for December 31, 2011 to January 6, 2012

January is best known for the Quadrantids, which have the potential of being the
best shower of the year. Unfortunately this shower is short lived and occurs
during some of the worst weather in the northern hemisphere. Due to the high
northern declination (celestial latitude) and short summer nights, little of
this activity can be seen south of the equator. Sporadic rates are generally
similar in both hemispheres this month. Sporadic rates are falling though for
observers in the northern hemisphere and rising as seen from the southern
hemisphere.

During this period the moon reaches it first quarter phase on Sunday January
1st. At this time the moon will be located ninety degrees east of the sun and
will set near midnight local standard time (LST). As the week progresses the
waxing gibbous moon will set later in the morning hours, shrinking the window of
opportunity to view under a dark sky. The estimated total hourly rates for
evening observers this week is near three as seen from the northern hemisphere
and two as seen from the southern hemisphere. For morning observers the
estimated total hourly rates should be near fifteen as seen from mid-northern
latitudes and ten from mid-southern latitudes. 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. Evening rates
are reduced due to moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions
and rates 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. 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. Viewing there 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.

The following showers are expected to be active this week:

The large Antihelion (ANT) radiant is currently located at 07:32 (113) +21. This
position lies in eastern Gemini, two degrees east of the fourth magnitude star
Wasat (Delta Geminorum). Due to the large size of this radiant, Antihelion
activity may also appear from Monoceros, Canis Minor, or Cancer. This radiant is
best placed near 0100 LST, when it lies on the meridian and is located highest
in the sky. Rates at this time should be near two per hour as seen from the
northern hemisphere and one per hour from south of the equator. With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of slow velocity.

The Alpha Hydrids (AHY) are active from December 31st through January 9th. Peak
activity occurs on January 1st from a radiant located at 08:24 (126) -08. This
position lies in extreme western Hydra, fifteen degrees west of the second
magnitude star Alphard (Alpha Hydrae). Rates would most likely be near one per
hour, no matter your location. The Alpha Hydrids are best seen near 0200 LST
when the radiant lies highest above the horizon. At 45 km/sec. the Alpha Hydrids
produce mostly meteors of medium velocity.

Studies of the IMO’s video database by Sirko Molau and Juergen Rendtel has
shown another active radiant in Leo this time of year. The January Leonids (JLE)
are active from January 1st to 6th with maximum activity occurring on January
2nd. On the 2nd the radiant is located at 09:46 (147) +24. This position lies in
western Leo just west of the third magnitude star Algenubi (Epsilon Leonis).
This is a very minor display with hourly rates of less than one expected, even
at maximum activity. They are best seen near 0300 LST when the radiant lies
highest above the horizon. At 54 km/sec. the January Leonids (JLE) produce
mostly meteors of medium-swift velocity.

The December Leonis Minorids (DLM) are active from a radiant located at 11:27
(172) +25. This position lies in a blank area of northeastern Leo. The nearest
bright star is third magnitude Zosma (Delta Leonis), which lies six degrees to
the southwest. These meteors are best seen near 0500 local standard time (LST)
when the radiant lies highest above the horizon. This shower peaked on December
20th so current rates would be near one per hour as seen from the northern
hemisphere and less than one per hour as seen from south of the equator. At 64
km/sec. the December Leonis Minorids produce mostly swift meteors.

The Quadrantids (QUA) or January Bootids are active from January 1st through the
10th. A sharp maximum is predicted to occur near 0730 Universal Time on the 4th.
This corresponds to 02:30 EST and 23:30 PST (January 3rd). This is good timing
for viewers located in eastern North America as the radiant will rising above
the northeastern horizon. It would even be better if the maximum were a it later
as the radiant would be located higher in the sky, producing more activity.
Rates will depend on the exact time of maximum and whether the moon is still
above the horizon. Assuming the 0730 UT timing is correct, the further one is
located in North America, the better. Eastern observers may be able to see 60-75
Quadrantids per hour. If your skies are very clear and dark, allowing you to see
faint meteors, your rates could top 100 per hour. Observers located in the
western portions of North American will have lower rates but will also have the
opportunity to see Quadrantid earthgrazers. Earthgrazers are meteors that
skim the upper portion of the atmosphere therefore lasting much longer than
normal and producing long trails in the sky. These meteors can only be seen when
the radiant lies close to the horizon. As the radiant rises, the meteor paths
will become shorter with shorter durations. Observers in the northern hemisphere
outside of North America can expect to see a maximum of 25 Quadrantids per hour
between moon set and dawn. Observers south of the equator will see little of
this display as the radiant will have little chance to clear the horizon before
morning twilight interferes.

At maximum the radiant is located at 15:21 (230) +49. This position lies in a
barren region of extreme northern Bootes, ten degrees northeast of the fourth
magnitude star Beta Bootis. At 42 km/sec. the Quadrantids produce meteors of
medium velocity. During exceptional activity some Quadrantid fireballs may be
witnessed.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately eight sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near two per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near seven
per hour as seen from rural observing sites and one per hour during the evening
hours. Locations between these two extremes would see activity between the
listed figures. Evening rates are reduced due to moonlight.

The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.