Meteor rates continue to be strong as seen from
the northern hemisphere. The antihelion radiant has now merged with the two Taurid
radiants producing slow meteors during the late evening and early morning hours.
Meteors from the Orionid radiant are visible most of the month. Strong sporadic
rates continue during the morning hours as long as the moon is below the horizon.
From the southern hemisphere, sporadic rates have reached their nadir and begin
a slow recovery the second half of the month. Meteors from the Taurid and Orionid
radiants also help to fill the southern skies with more activity than has been seen
since July. A new moon during the peak of the Orionid shower is a plus for all and
should help inflate meteor totals that have suffered since the Perseid maximum
back in August.
This week the moon reaches its last quarter phase
on Saturday October 14. At this time the moon will rise near 0100 local daylight
time (LDT) and will interfere somewhat with meteor observing during the prime
morning hours. The estimated total hourly rates for evening observers this week
is near three for those north of the equator and one for observers south of the
equator. For morning observers the estimated total hourly rates should be near
twenty for northern observers and eight for those 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. Morning rates are reduced due to moonlight.
The radiant positions listed below are exact for Saturday
night/Sunday morning October 14/15. 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 showers are expected to be active this week:
At this time of year debris from comet 2P/Encke produces a double radiant very
close to the position of the antihelion radiant. From now through the end of
November, it is impossible to resolve the antihelion meteors from those produced
by comet 2P/Encke. Therefore we suggest that observers simply classify meteors
from this area as either north or south Taurids. Although the radiants actually
lie in Aries during October, they reach maximum activity in November when they
are situated in the constellation of Taurus.
The Northern Taurid (NTA) radiant is now centered at 02:16 (034) +16. This
position lies in central Aries, seven degrees southeast of the second magnitude
star Hamal (Alpha Arietis). The Southern Taurid (STA) radiant lies at 02:24
(036) +11. This position lies in southern Aries, near the faint star Xi Arietis.
The two radiants are separated by slightly over five degrees. Since they have
nearly the same right ascension (celestial longitude), it is difficult to
distinguish meteors that move north or south out of the radiants. It is slightly
less difficult to distinguish those meteors traveling east or west.
These radiants are above the horizon most of the night and are best placed near
0100 LDT, when they lie on the meridian and are located highest in the sky. Rates
at this time should be near two per hour for the southern radiant and one per hour
for the northern radiant, regardless of your location. With an entry velocity near
30 km/sec., the average Taurid meteor would be of medium-slow speed.
The Orionids (ORI) are active from a radiant
located at 06:04 (91) +15. This position lies in northeastern Orion, eight degrees
northeast of the first magnitude star Betelgeuse (Alpha Orionis). The radiant rises
near 2300 LDT and is best placed on the meridian near 0500. Current rates would
be near five per hour over the weekend, increasing to near ten per hour late in
the period. The Orionids reach a broad maximum centered on October 21, when hourly
rates near twenty can be seen from rural locations, regardless of your location.
At 64km/sec., the average Orionid is swift.
The Epsilon Geminids (EGE) peak on October 18
with a predicted ZHR of two. This radiant is currently located at 06:36 (99) +27,
which places it in northwestern Gemini, two degrees northwest of the third
magnitude star Epsilon Geminorum. The radiant is best placed near 0500 when it
lies highest in the sky. To differentiate this shower from the nearby Orionids,
one must have both radiants within their field of view. Meteors traveling north
or south out of the radiants should be easy to classify. Those moving east or
west will be more difficult as you must rely on path length and angular velocity
to make a correct classification. At 70km/sec., the average Epsilon Geminid is
swift with a high percentage of persistent trains.
Sporadic rates have reached the late year plateau
for observers located in the northern hemisphere. One would expect to see perhaps
twelve random meteors during the last hour before dawn from rural observing sites.
During the first dark hour after the end of evening twilight, perhaps four random
meteors can be seen per hour. Sporadic rates increase as the night progresses so
rates seen near midnight would be near eight per hour. Sporadic rates seen from
the southern hemisphere have reached their annual minimum. One would expect to
see approximately three random meteors per hour during the last hour before dawn
and one per hour during the first dark hour after the end of evening twilight.
Rates near midnight would be near two per hour. Morning rates are reduced due to
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS*|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Time||North-South|
|Northern Taurid (NTA)||Nov 12||02:16 (034) +16||29||01:00||1 – 1||II|
|Southern Taurid (STA)||Nov 5||02:24 (036) +11||27||01:00||2 – 2||II|
|Orionids (ORI)||Oct 21||06:04 (91) +15||66||05:00||5 – 5||I|
|Epsilon Geminids (EGE)||Oct 18||06:36 (99) +27||71||05:00||1 – >1||II|
*For a detailed explanation on the different classes of meteor showers and other
astronomical terms, please visit: