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(meteorobs) NAMN Notes: October 2003
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NAMN Notes: October 2003
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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 - from Halley's Comet...
2. Draconids - from Comet Giacobini-Zinner...
3. Other October Meteor Activity...
4. Upcoming Meetings...
5. For more info...
1. Orionids - from Halley's Comet...
October brings our fall season - and our 'falling stars' from the
constellation of Orion. Whether you are a beginning observer, or a serious
observer gathering data for meteor research, this meteor shower holds many
delights!
The Orionids (ORI) reach a maximum on October 21st, at 21h UT, according to
the IMO, the International Meteor Organization, 2003 Meteor Shower Calendar.
They can be seen from about October 2nd through until about November 7th.
ZHR rates at maximum are about 20 meteors per hour. ZHR refers to Zenithal
Hourly Rate, and is the number of meteors, on the average, that an observer
would expect to see if they were 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. These are fast meteors, with a velocity of about 66 km
per second.
According to the IMO: "October's waning crescent Moon partly
favors the Orionids near their best. They are noted for having several
maxima other than the main one above, with activity sometimes remaining
almost constant for several consecutive nights centered on this peak."
A good diagram showing where these meteors come from in the sky can be found
on Gary Kronk's excellent 'Comets and Meteor Showers' website at
http://comets.amsmeteors.org/meteors/showers/orionids.html A more detailed
sky map showing the movement of the radiant position over time can be found
on the IMO website at http://www.imodot net/calendar/cal01.html#Orionids. At
the time of maximum activity, around the 21st, the radiant will be at 095
degrees, ie. RA 6h 19.8m, Dec +16, which is located by following a line from
the right star of the belt of Orion up through Betelgeuse, the left shoulder
star, and continuing on for about the same distance again.
Orion is the most prominent and most easily recognizable constellation in
the northern winter sky. In one version of ancient mythology, Orion was the
son of Poseidon, the sea god, and Euryale, one of the Gorgon's sisters, and
was born in the Greek province of Boeotia. He was a handsome hunter - and
enjoyed both hunting and women. He fell in love with Merope, the daughter
of King Oenopion of the island of Khios, and was set a task by the king in
order to win his daughter. The king went back on his deal, Merope told
about Orion's rough treatment of her, and Oenopion blinded Orion and ditched
him on a seashore. Orion recovered his sight, with help from Eos, the
goddess of the dawn, and set off for vengeance.
He traveled to the island of Crete searching for King Oenopion, and met
Artemis, the beautiful goddess of the Moon. Orion and Artemis fell in love,
and he forgot about vengeance. However, Artemis forgot about everything
else in her passion for Orion - and she forgot her duty to carry the Moon
across the sky. After a month with no moon, Artemis' brother Apollo, god of
light and other things, got fed up and decided to get rid of Orion. One day
when Orion was out swimming, Apollo challenged Artemis, a good bowhunter, to
hit a small dark object a long distance away in the water. Artemis took the
challenge - and unknowingly killed her lover. She was devastated. She took
Orion's body to her nephew Esculapius, god of medicine and healing, to try
to make him live again. A thunderbolt from Zeus intervened, and Orion's
body was destroyed. Artemis wept, and set her lover among the stars.
The Orionid meteors are debris from the famous Halley's Comet. Both Halley
and his comet make for interesting reading as well. Edmond Halley was born
in Haggerston, England in 1656, and died in Greenwich, England in 1742. His
accomplishments were quite varied. He improved the sextant. He sailed to
the southern hemisphere and collected data on the ocean and atmosphere - and
published the first meteorological chart in the world. He catalogued 341
southern hemisphere stars, and discovered a star cluster in Centaurus. He
made the first complete observation of a transit of Mercury. Halley urged
Newton to publish his 'Principia Mathematica', and paid for the costs out of
his own pocket. While sailing the Atlantic Ocean in command of a warship,
courtesy of King William III, Halley made studies of longitude and tides.
In the realm of comets, Halley believed that elliptical orbits might exist.
He believed that the comets of 1531, 1607 and 1682 were all the same
comet - a periodic comet - and predicted that it would return again in 1758.
When the prediction came true, after Halley's death, the periodic comet was
renamed in his honor.
Halley's Comet has been traced back to the year 240 B.C. According to
Kronk, "the computed motion of the comet indicates it would have appeared in
the east, moved through northern skies, and then would have been seen in the
western sky". The closest approach of the comet to earth was in the year
837, when we were separated from the comet by only 3.2 million miles, .0342
AU, Astronomical Units. The tail reached about 60 degrees across the sky.
The recent appearance of Halley's Comet in the 1980's produced a tail of
about 15 degrees in length, and a maximum brightness of about 2.6, fainter
than the stars of the Big Dipper. Halley is not one of the brightest comets
of our time - but it is one of the most well publicized due to the history
of its discovery. Some photos of Halley's Comet can be found on Kronk's
'Cometography' website at http://cometography.com/pcomets/001p.html
The discovery of the Orionid meteors themselves is generally credited to
Edward Herrick in 1839. Precise observations of the radiant were first made
in 1864 by Alexander Herschel. The first measurements of meteor rates for
the shower were done in 1892. The link between the shower and the comet
came indirectly. It had been known since 1868 that the Eta Aquarid meteor
shower in May was related to Halley's Comet. In 1911, Charles Olivier
mentioned the similarity of the orbit of the Orionids to that of the Eta
Aquarids - and hence the first linkage in turn was made to Halley's Comet,
although it was not generally accepted until a number of years later.
Orion is easy to find in our night sky - if you need help, print off some of
our online star maps at http://www.namnmeteors.org/charts.html
For details on what to record, if you want to contribute useable data, check
out our NAMN Observing Guide at http://www.namnmeteors.org/guide.html.
The information to record while observing is fairly basic... data for each
meteor, such as time it occurred, magnitude (brightness), shower it belongs
to, speed, and other comments such as train left behind, or color. General
information to record includes such things as how dark your perceived sky is
(limiting magnitude), and comments on weather and cloud cover. Forms to
record your observations can be found at
http://www.namnmeteors.org/namn_form.html and
http://www.namnmeteors.org/appendixC.html. Any questions on what to record,
or how, can be sent to our NAMN Coordinator at meteors@comcastdot net
Get out and take a look at this debris from Halley's Comet. For beginning
observers, this shower is a real treat. For more serious observers, your
data is very useful!
2. Draconids - from Comet Giacobini-Zinner...
The Draconids (GIA) reach a maximum on October 9th, with a radiant 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. This shower is
named both after the constellation from where the meteors come, and after
the parent body of the meteors, Comet Giacobini-Zinner. For a detailed map
showing the position of the radiant, check out the IMO website at
http://www.imodot net/calendar/cal02.html#Draconids. A simpler version can be
found on Kronk's 'Comets and Meteor Showers' website at
http://comets.amsmeteors.org/meteors/showers/draconids.html
These are slow meteors, with a velocity of about 20 km per second - so are
very distinctive, and quite spectacular. They have been known to storm on
rare occasions, such as in 1933 and 1946 - and are listed as 'variable' by
the IMO. This is a shower to monitor. This year, full moon is on October
10th, so faint meteors will be washed out. However, the brighter meteors
will still be visible. Face away from the moon, or block it from your field
of view.
According to the IMO, the International Meteor Organization, peak times to
watch for include:
October 8 20h UT (the equivalent 1998 outburst time)
October 9 04h UT (nodal crossing time)
October 9 9.30-12.40 UT (the equivalent 1999 minor outburst time)
For observers on the east coast of North America, these times translate to
October 8th at 4 p.m. EDT, October 8th at midnight EDT, and October 9th at
5.30-8.40 a.m. EDT.
Draco is a north circumpolar constellation, and one we don't usually think
too much about. It winds between the Big Dipper and the Little Dipper. In
ancient mythology, Draco was known as Ladon, the dragon. It was the
dragon's duty to guard the three golden apples that Hera gave Zeus as a
wedding gift. These apples were kept in the Garden of Hesperides, which was
owned by Atlas. Atlas was tricked by Herakles to steal the apples (one of
his 'twelve labors'), and take a break from carrying the world on his
shoulders. Poor Ladon the dragon was duped by his own master. Hera was
furious that the apples were gone... and placed the dragon in the
circumpolar constellations, to guard the heavens without ever setting or
resting.
The parent comet of the Draconids is Comet Giacobini-Zinner. It was
discovered by Michel Giacobini of France in 1900, and also by Ernst Zinner
of Germany in 1913. The comet is a short period comet, returning about
every 6 1/2 years. The 1946 return was notable as the comet passed only
0.26 AU, Astronomical Units, in distance from the earth. The comet reached
magnitude 6, and a meteor storm was encountered. The most recent return was
in 1998. Some photos of Comet Giacobini-Zinner can be found on Kronk's
'Cometography' website at http://cometography.com/pcomets/021p.html
The first prediction for a meteor shower from this comet was made in 1915 by
Reverend M. Davidson. Meteors from the predicted radiant were observed by
William Denning. In 1933, a wonderful storm was seen - with observers
reporting meteors falling like snowflakes, with rates of about 100 meteors
per minute (6000 per hour) depending on observer and location. The meteors
were described as faint, with most being between magnitude 3 and 5. They
were slow, and most were yellow in color. In 1946, Czechoslovakian
observers saw a corrected rate of about 6800 meteors per hour. That year
was the first time a meteor shower was detected also by radar.
What can we expect from the Draconids this year? This shower can be seen
from October 6th to 10th. If you have clear skies, get out and monitor this
activity please! This shower is listed as 'variable'. We do not know how
many, or how few, meteors will come flying over our skies. The Draconids
are a surprise waiting to happen!
3. Other October Meteor Activity...
The delta Aurigids (DAU), although reaching a maximum in September, can
still be seen until about October 10th. These are fast meteors, with a
velocity of about 64 km per second. A map of the radiant can be found at
http://www.imodot net/calendar/cal03.html#alpha-Aurigids. ZHR rates at maximum
were about 6 meteors per hour, but rates in October will be lower. The
parent body responsible for these meteors is uncertain.
The epsilon Geminids (EGE) reach a maximum on October 18th, but can be seen
from about October 14th to 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. These are fast meteors, at about 70
km per second. These meteors might be associated with either Comet Ikeya,
C/1964 N1, or Comet Nishikawa-Takamizawa-Tago, C/1987 B1. ZHR rates for
this shower are about 2 meteors per hour at maximum. For a map of the
radiant, see http://www.imodot net/calendar/cal01.html#Orionids.
The northern Taurids (NTA) and southern Taurids (STA) start to become active
about October 1st, but do not reach maximums until early November. Both
have fairly slow meteors, with the northern Taurid velocity at 29 km per
second, and the southern at 27 km per second. At maximum in November, both
showers will peak at about ZHR rates of 5 meteors per hour. These meteors
are part of the Taurid stream which in turn has been associated with Comet
Encke. The IMO states that "this year would be a good year to check for any
additional unusual activity". For a map showing the movement of the Taurid
radiants throughout October and November, check out
http://www.imodot net/calendar/cal02.html#Taurids.
Besides recognized main showers, and other minor showers, there is also
sporadic meteor activity in October. This sporadic activity is about 7
meteors per hour, visible to the unaided eye. This activity is comprised
partly of random meteors and partly of meteors that belong to long-ago, now
untraceable showers.
This month, the phases of the moon are as follows:
Thurs. Oct. 2 first quarter
Fri. Oct. 10 full moon
Sat. Oct. 18 last quarter
Sat. Oct. 25 new moon
Planets at midmonth, and their magnitudes, for northern observers, are:
Mars -1.8 in Aquarius
Saturn 0.1 in Orion
Jupiter -1.8 in Leo, in morning sky
Venus -3.9 very low in west in evening
The planets are very good 'standards' for estimating the magnitude of bright
meteors. On October 6th, Mars will be very close to the moon in the sky
(1.1 degrees) and on October 26th, Venus and the moon will be close together
(0.08 degrees).
4. Upcoming Meetings...
June 4-6, 2004, Paris, France...
IWCA III, the Third International Workshop on Cometary Astronomy, will be
held at the Meudon and Paris Observatories in Paris, France.
The workshop announcement states that "its main objective is to promote
cometary observations among amateur astronomers and optimize the benefit of
these observations for the use by professional astronomers... it shall be
an opportunity for amateurs to meet professionals and exchange about their
techniques". Topics to be discussed include comet photometry, outgassing
rates, imaging with filters and spectroscopy, astrometry, observation of
trans-neptunians by amateurs, discovery and automatic sky surveys, space
missions to comets, and internet tools. Information can be found
at http://www2.iap.fr/saf/IWCAIII. The contact for information is
Nicholas Biver, nicolas.biver@obspm.fr. There is some financial support
available for participants from eastern Europe or other countries with
limited financial resources. The workshop has been timed to coincide with
the transit of Venus on June 8th, visible from France.
For more information on upcoming astronomy meetings, see: "International
Astronomy Meetings List" at http://cadcwww.hia.nrcdot ca/meetings
5. For more info...
NAMN email: namn@atmob.org
NAMN website: http://www.namnmeteors.org
Mark Davis, meteors@comcastdot net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network
Cathy Hall, chall@cyberusdot ca
Metcalfe, Ontario, Canada
Writer, NAMN Notes
Lew Gramer, dedalus@alum.mitdot edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'
Kevin Kilkenny, namnfireball@earthlinkdot net
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites
Back issues of NAMN Notes can be found online 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:
Contact Lew Gramer at: dedalus@alum.mitdot edu
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Here's to 'Clear Skies' for October...
October 2003 NAMN Notes
written by Cathy Hall & edited by Mark Davis
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