[Prev][Next][Index][Thread]
(meteorobs) NAMN Notes: October 2001
************************
NAMN Notes: October 2001
************************
Introduction:
NAMN Notes is a monthly newsletter produced by the North American Meteor
Network, and is available both via email, and on the NAMN website at:
http://www.namnmeteors.org
Contents:
1. Orionids - Debris from Halley's Comet...
2. Other October Showers...
3. Preparing for Leonids...
4. Upcoming Meetings...
5. For more info...
1. Orionids - Debris from Halley's Comet...
The Orionids (ORI) reach a maximum on October 21st this year, at 08h
UT. UT refers to Universal Time, and is the time at Greenwich, England, so
you should check your own time zone accordingly. The ZHR, Zenithal Hourly
Rate, is about 20 meteors per person per hour, visible with the unaided
eye, if an observer is out under a dark country sky, and if the radiant,
the area in the sky where the meteors seem to come from, is directly
overhead.
The radiant at maximum on the 21st will be at 95 degrees, ie RA 6h 19.8m,
Dec +16, which is almost in the foot of Gemini, about 4 degrees to the
right of the star gamma Gemini, the star Alhena. The radiant (for
comparison) on October 10th will be at 88 degrees, ie RA 5h 52.2m, Dec +15,
which is very near the star 135 Taurus, about 7 degrees north of Betelgeuse
in Orion.
These are fast meteors, with a velocity of about 66 km per second, and can
be seen from about October 2nd through until about November 7th.
According to the IMO, the International Meteor Organization, in their 2001
Meteor Shower Calendar:
"October's waxing crescent moon enhances the Orionids this year too. They
are noted for having several maxima other than the main weekend one
detailed above, with activity sometimes remaining almost constant for
several consecutive nights centred on this peak... All observers should be
aware of these possibilities."
A map showing the movement of the Orionid radiant throughout October can be
found at http://www.imodot net/calendar/cal01.html#Orionids. The Orionid
radiant is the line labeled ORI.
The parent body of this meteor shower is the famous Halley's Comet! Edmond
Halley was appointed to the Chair of Geometry at Oxford University in 1704,
and went on to do an orbital study of several dozen comets observed between
1337 and 1698. It was during this study that he noticed similarity between
some of the comets. Once some of these were confirmed to be different
apparitions of the same comet, his name became attached - and Comet Halley
went on to become famous.
According to Gary Kronk's wonderful book "Comets - A Descriptive Catalog",
20th century astronomers have traced Halley's Comet back to 240 BC. In the
year 374, it was about magnitude -3.0, with a tail length of about 100
degrees across the sky. In the year 837 it reached about magnitude -2.0
with a 100 degree tail. In 1066 it was noted as brighter, about magnitude
-4.0, but no description of tail length was found. In the middle ages,
tail lengths seemed to be noted as shorter. In 1910, Halley's Comet
reached a magnitude of about 0.0, with a noted tail length of 90
degrees. Too bad that we have so much light pollution these days... it is
getting harder for the general public to see such wondrous sights!
The debris from this wonderful comet is still worth watching for - try to
get out of the city and away from all the lights to enjoy the shooting
stars from this famous comet!
2. Other October Showers...
The delta Aurigids (DAU), although having reached a maximum back on
September 8th, with ZHR rates of about 6 meteors per hour, are visible in
lesser numbers until about October 10th. These are fast meteors, with a
velocity of about 64 km per second. At last quarter moon on the 10th, the
radiant will be at 95 degrees, ie RA 6h 19.8m, Dec +49, which is very near
the star psi#1 Auriga. There is a questionable link between these meteors
and Comet Bradfield, C/1972 E1. For a map showing the radiant, check out
last year's IMO calendar at
http://ww.imodot net/calendar/cal00.html#delta-Aurigids.
The Draconids (GIA), also known as the Giacobinids, reach a maximum on
October 8th - and are well worth monitoring! The radiant at maximum is at
262 degrees, ie RA 17h 28.2m, Dec +54, which is just north of the star beta
Draconis, also known as Restaban, in the head of Draco. These are slow
meteors, at about 20 km per second, and can be seen from about October 6th
to 10th. This shower is named both after the constellation where the
radiant is, and after its parent body, Comet Giacobini-Zinner.
Giacobini-Zinner is a short period comet, returning about every 6.61 years.
The meteor rates are variable - and have stormed in the past, such as in
1933 and 1946 when thousands were seen! This is one of those wonderful
showers well worth watching for any surprises! For a map showing the
radiant, again, check out last year's IMO calendar at
http://www.imodot net/calendar/cal00.html#Draconids.
The epsilon Geminids (EGE) reach a maximum on October 18th, although can be
seen from about the 14th to the 27th. On the 18th, the radiant will be at
102 degrees, ie RA 6h 48m, Dec +27, which is several degrees north of the
star epsilon Gemini, also known as Mebsuta. A map showing the movement of
the radiant can be found at http://www.imodot net/calendar/cal01.html#Orionids.
ZHR rates at maximum are low, about 2 meteors per hour. These are fast
meteors, moving at about 70 km per second. The parent comet is theorized to
be either possibly Comet Ikeya, C/1964 N1, or Comet
Nishikawa-Takamizawa-Tago, C/1987 B1.
Both the southern Taurids (STA) and the northern Taurids (NTA) start to
become active around October 1st, but do not reach maximum until early
November. Both have fairly slow meteors, the STA's being about 27 km per
second and the NTA's about 29 km per second. At maximum, both showers
will have ZHR rates of around 5 meteors per hour, but rates in October will
be lower. On October 10th, near the time of the Draconids, the NTA radiant
will be at 29 degrees, ie RA 1h 55.8m, Dec +14, which is about 7 degrees
south of the star beta Aries, known as Sharatan. The STA radiant on the
10th will be at 31 degrees, ie RA 2h 4.2m, Dec +8, which is about 5 degrees
north of the star alpha Pisces. There is a group of objects possibly
associated with the Taurid meteor stream, as parent or sibling bodies,
including Comet Encke, and the splitting of these bodies is theorized to
have perhaps happened as long ago as 100,000 years in the past, depending
on which theories are considered. A map of the northern and southern
Taurid radiants can be found in the IMO calendar for 1999, at
http://www.imodot net/calendar/cal99.html#Taurids.
There are always very minor showers active as well, but they are not always
included on the IMO "Working List of Visual Meteor Showers". For extra
reading, you can check out Gary Kronk's "Comets and Meteor Showers" website
at http://comets.amsmeteors.org.
Besides recognized showers, there is also sporadic meteor activity in
October, about 7 meteors per hour, visible to the unaided eye. This
activity is comprised partly of random meteor activity and partly from
meteors that belong to long-ago, now untraceable showers.
Full moon this month is on Tuesday, October 2nd; last quarter on Wednesday
October 10th; new moon on Tuesday October 16th, and first quarter on
Wednesday October 24th.
The planets continue bright. Venus, in the morning sky is at about
magnitude -4. Jupiter is in Gemini, at about magnitude -2.3 for most of
the month. Saturn is in Taurus at about magnitude -0.6 for October. Both
Jupiter and Saturn will be up most of the night for northern
observers. Mercury, at about magnitude 1.4 in late October, will be within
1 degree of Venus for 11 days in late October and early November. For more
info on the moon and planets, check out http://www.heavens-above.com,
"Select" your location, and then check out the options.
For information on what we record when we watch meteors, check out our
Observing Guide at: http://www.namnmeteors.org/guide.html. We also have a
great set of star charts to use while observing - showing the
constellations, sky coordinates, and the magnitudes of stars useful in
judging the brightness
of the meteors you see. Check them out at:
http://www.namnmeteors.org/charts.html.
3. Preparing for Leonids...
Next month brings the Leonid meteor shower - probably the most awaited
meteor event of 2001. Here are several reading links to help prepare
you. You should start thinking now about where you want to be to observe
this unusual event! November will come very soon...
What is this shower?
Joe Rao has an excellent article on the Sky & Telescope website, called
"The Leonids: King of the Meteor Showers":
http://www.skypub.com/sights/meteors/leonids/king.html
The Astronomical Society of Australia has an Information Sheet, "The Leonid
Meteor Shower", with information provided by Rob McNaught, at:
http://www.atnf.csiro.au/asa_www/info_sheets/leonids.html
Where should I go to watch it?
Check out the detailed "Encounter Conditions 2000-2002" on the Leonid MAC
homepage:
http://leonid.arc.nasadot gov/1998.html.
Predictions for various locations are given, based on a variety of
different models by various researchers.
Why is it so special?
Check out the history and past observations of the Leonid meteor shower on
Gary Kronk's "Comets and Meteor Showers" website at:
http://comets.amsmeteors.org/meteors/showers/leonids.html
When does it happen?
All of the nights around November 17th and 18th should be monitored -
before the maximum, during the maximum, and after the maximum. Surprises
can always occur.
The International Meteor Organization (IMO), in their 2001 Meteor Shower
Calendar, lists the period of activity of the Leonid shower as November
14th to 21st. Various prediction theories give various times of maximum
activity centered on November 17th and 18th. The website of the IMO
can be found at http://www.imodot net.
Who has more info for me to read up on?
Stay tuned to our "Meteorobs" email list. We are the best source in
town! If you are reading this newsletter, and are not yet on our email
list, consider subscribing so that you too can hear the latest Leonid
predictions and news, as they happen! To subscribe, go to our Subscriber
form at: http://www.meteorobs.org/subscribe.html.
4. Upcoming Meetings...
There are no meetings to report this month, but bookmark the following
site, which you may find handy for future reference:
"International Astronomy Meetings List"
http://cadcwww.hia.nrcdot ca/meetings
5. For more info...
Contact:
Mark Davis, SC.meteors@home.com
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network
And check out:
NAMN home page:
http://www.namnmeteors.org
Back issues of NAMN Notes can be found on-line at the NAMN website, and
in the meteorobs archives at:
http://www.meteorobs.org
by selecting 'Browse Archive by Month'
To subscribe to the meteor email list or
To find out information on our weekly chat sessions:
Contact Lew Gramer at:
dedalus@alum.mitdot edu
============================================
Here's to 'Clear Skies' for October...
October 2001 NAMN Notes co-written
by Mark Davis and Cathy Hall
============================================
To stop getting email from the 'meteorobs' list, use the Web form at:
http://www.meteorobs.org/subscribe.html
Follow-Ups: