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 first
quarter phase on Tuesday October 7th. At this time the moon will be located ninety
degrees east of the sun and will set near 0100 local daylight time (LDT). This will
allow excellent conditions during the more active morning hours. 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 twenty for those located in the mid-northern hemisphere (45 N) and ten 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.
Evening rates are slightly reduced due to moonlight.
The radiant positions and rates listed below are exact
for Saturday night/Sunday morning October 4/5. 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 Draconids (GIA) (also known as the Giacobinids) reach maximum activity
on October 8. The exact time of maximum activity can vary so observers are
encouraged to view on the evenings of October 7-9 to try and catch any of this
activity.The radiant is located at 17:28 (262) +54, which places it in southern
Draco, two degrees northwest of the third magnitude star Rastaban (Beta Draconis).
This star is one of the four that form the prominent head of Draco, also known as
the “Lozenge”. Expected rates are always a guess. The first quarter moon will
slightly interfere. Those located in high northern latitudes can also try viewing
this shower during the morning hours when the moon is absent. Due to the extreme
northern declination, this shower is only visible from the southern tropics northward.
The radiant is best placed just as it becomes dark during the evening hours. At
20km/sec., the average Draconid is extremely slow.
The center of the large Northern Taurid (NTA) radiant is now centered at
01:44 (026) +14. This position lies in eastern Pisces, two degrees southeast of
the fourth magnitude star Eta Piscium. The center of the large Southern Taurid
(STA) radiant lies at 01:52 (028) +08. This position also lies in eastern Pisces,
near the fourth magnitude star Omicron Piscium. 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 noticeable from a radiant located at
05:40 (85) +14. This position lies in northern Orion, six degrees northwest 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 one to
two per hour as seen after midnight. At 66km/sec., the average Orionid is swift.
The Delta Aurigids (DAU) are present in the morning skies in the second half
of September and early October. Maximum activity occurred on October 3rd with an
average ZHR of two. Current rates will be most likely near one per hour as seen
from the northern hemisphere and less than one as seen from the south of the
equator. The radiant is currently located 05:56 (089) +49. This position lies in
northwestern Auriga, five degrees northeast of the zero magnitude star Capella
(Alpha Aurigae). At 64km/sec., the average Delta Aurigid is swift.
During 2005 and 2006 a shower of bright meteors has occurred on October 5th and 6th,
radiating from near the Draco/Camelopardalis border. The 2007 display was missed
due to moonlight and clouds. The October Camelopardalids (OCT) peak for only
a few hours but shower members are bright and should be easy to observe. The 2008
display is predicted to occur near 14 UT on October 5th, which corresponds to 0700
PST. It is daylight at this time from the USA’s west coast but observers along the
Pacific coast of Canada and Alaska can view at this time. The last hour before dawn
may provide some activity as seen from the western USA and Canada. The estimated
position of the radiant on the 5th is 10:48 (162) +79. The nearest easy star to
identify the radiant is 4th magnitude SAO1551. Polaris (Alpha Ursae Minoris) lies
12 degrees to the north. This area of the sky is circumpolar from nearly the entire
northern hemisphere. The radiant lies highest above the horizon in a dark sky at
both dusk and at dawn. Due to this unusual situation this shower would be totally
invisible from the southern hemisphere. With an entry velocity of 47 miles per
second most members of the October Camelopardalids would be of medium-swift
velocity. Shower members should be seen from October 1-10, but at very low numbers
away from the peak hour on the 5th.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately
fifteen 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 four 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 slightly reduced during the evening hours due to moonlight.
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|
|Draconids (GIA)||Oct 08||17:28 (262) +54||20||17:00||<1 – <1||III|
|Northern Taurid (NTA)||Nov 12||01:44 (026) +14||29||02:00||2 – 2||II|
|Southern Taurid (STA)||Nov 05||01:52 (028) +08||27||02:00||3 – 3||II|
|Orionids (ORI)||Oct 21||05:40 (085) +14||66||06:00||1 – 1||I|
|Delta Aurigids (DAU)||Oct 03||05:56 (089) +49||64||06:00||<1 - <1||II|
|October Camelopardalids (OCT)||Oct 05||10:48 (162) +79||47||11:00||<1 – <1||IV|