Meteor activity in general increases in October
when compared to September. A major shower (the Orionids) is active most of the
month along with several minor showers. Both branches of the Taurids become more
active as the month progresses, providing slow, graceful meteors to the nighttime
scene. The Orionids are the big story of the month reaching maximum activity
on the 21st. This display can be seen equally well from both hemispheres
which definitely helps out observers located in the sporadic-poor southern hemisphere
this time of year.
During this period the moon reaches its full
phase on Tuesday October 14th. At this time the moon will rise near sunset and
set near sunrise and will be in the sky all night long. This weekend there will
be a small window of darkness between moonset and morning twilight when observing
can be attempted under good conditions. The estimated total
hourly rates for evening observers this week is near five for those located in
the mid-northern hemisphere (45 N) and two for those viewing from the mid-southern
hemisphere (45 S). For morning observers the estimated total hourly rates should
be near fifteen for those located in the mid-northern hemisphere (45 N) and five for
those viewing from the mid-southern hemisphere (45 S). Locations between these
two extremes would see activity between the listed figures. 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 listed rates are reduced due to moonlight.
The radiant positions and rates listed below are exact
for Saturday night/Sunday morning October 11/12. 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:
Sirko Molau’s studies of video radiants has revealed activity in Ursa Minor
between October 10 and 16, peaking on the 12th. The position at maximum
activity is 16:32 (248) +82. This position lies in central Ursa Minor near
the faint star Epsilon Ursae Minoris. Visual activity is expected to be low,
but detectable. The radiant is best placed as soon as it becomes dark during
the evening hours. Due to the high northern declination (celestial latitude) this
activity is invisible from the southern hemisphere. At 35km/sec., the average
Epsilon Ursae Minorid (EUM) will appear as medium-slow.
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 center of the large Northern Taurid (NTA) radiant is now centered at
02:04 (031) +15. This position lies in southwestern Aries, eight degrees south of
the second magnitude star Hamal (Alpha Arietis). The center of the large Southern
Taurid (STA) radiant lies at 02:12 (033) +09. This position also lies in
southwestern Aries, five degrees south of the second magnitude star Hamal (Alpha
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 less
difficult to distinguish those meteors traveling east or west. These radiants are
best placed near the meridian at 0200 LDT. At 29 and 27 km/sec., the average Taurid
meteor travels slowly through the skies.
The Orionids (ORI) are now becoming more active from a radiant located at
05:56 (89) +15. This position lies in northeastern Orion, seven degrees north of
the orange first magnitude star Betelgeuse (Alpha Orionis). The radiant rises
near 2300 LDT and is best placed on the meridian near 0500. With maximum activity
predicted for October 21, current rates for all locations would be near two to
three per hour as seen after midnight. At 66km/sec., the average Orionid is swift.
The Epsilon Geminids (EGE) reach a ZHR of one on October 14th. The radiant
is located at 06:24 (096) +27. This position lies in western Gemini, three degrees
northwest of the third magnitude star Epsilon Geminorum. Maximum activity is predicted
to occur on October 18 with an average ZHR of two. Current rates will be most
likely less than one per hour. At 70km/sec., the average Epsilon Geminid is
Sirko Molau’s studies of video radiants has revealed activity in northern
Cancer between October 10 and November 4, peaking on the October 14th. The radiant
for the Iota Cancrids (ICA) lies at 08:44 (131) +29. This position lies very
close to the fourth magnitude star Iota Cancri. Visual activity is expected to be
low, especially with the moon nearing it’s full phase. After this weekend observers
will not get a chance to view this activity under dark skies until late in the month.
The radiant rises near 0200 LDT and is best placed high in the east during the last
dark hour of the morning. At 67km/sec., the average Iota Cancrid will appear move
swiftly through the skies.
Another radiant discovered during Sirko Molau’s studies of video radiants Is the
Tau Ursae Majorids (TUM). This shower is active between October 15th and the 22nd,
peaking on the 16th. The radiant lies at 09:36 (144) +65. This position lies in
western Ursa Major near the faint star 23 Ursae Majoris. Again visual activity is
expected to be low with the moon nearing it’s full phase. The radiant is circumpolar
north 25 degrees north latitude and is best seen during the last hour before dawn
when it lies highest above the horizon in a dark sky. At 54km/sec., the average
Tau Ursae Majorid meteor will appear move swiftly through the skies.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately
ten Sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near three per hour. As seen from the
mid-southern hemisphere (45S), morning rates would be near three 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. Rates
are reduced during this period due to the bright moon.
The table below presents a summary of the expected activity this week. Rates and
positions are exact for Saturday night/Sunday morning but may be used all week.
|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|
|Epsilon Ursae Minorids (EUM)||Oct 12||16:32 (248) +82||35||17:00||<1 – 0||IV|
|Northern Taurids (NTA)||Nov 12||02:04 (031) +15||29||02:00||1 – 1||II|
|Southern Taurids (STA)||Nov 05||02:12 (033) +09||27||02:00||2 – 2||II|
|Orionids (ORI)||Oct 21||05:56 (89) +15||66||06:00||2 – 2||I|
|Epsilon Geminids (EGE)||Oct 18||06:24 (096) +27||70||06:00||<1 - <1||II|
|Iota Cancrids (ICA)||Oct 14||08:44 (131) +29||67||08:00||<1 – <1||IV|
|Tau Ursae Majorids (TUM)||Oct 16||09:36 (144) +65||54||09:00||<1 – <1||IV|