Sziasztok!
Nem tudom, talan sokaknak uj dolog a North American Meteor Network´s
Notes, ami havonta megjeleno meteoros informacioforras... Bar angolul van,
hatha erdekesnek talaljatok. (Szerintem azert segiti az
eszlelomunkat...). Nem kuldenem el havonta a listara, de akit erdekel a
jovoben is, az az ""Introduction"-jeben leirt modon elofizetheti ingyen.
Udv: Szilard
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NAMN Notes: December 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. Geminids - Debris from an Asteroid...
2. Other December Activity...
3. Christmas Ideas for Meteor Observers...
4. Upcoming Meetings...
5. For more info...
1. Geminids - Debris from an Asteroid...
The Geminids (GEM) are the highlight of December and our winter season!
They can be seen from about December 7th to 17th and reach a maximum on
December 14th at about 11:40 UT, plus or minus about 2.5 hours according to
the International Meteor Organization (IMO). For observers in eastern
North America, this makes the night of December 13th and the pre-dawn hours
of December 14th prime time.
The radiant at maximum, the area of the sky where the meteors seem to come
from, will be at 112 degrees, ie. RA 07h 28.2m, Dec +33, which is close to
the bright star Castor in the constellation of Gemini - the twins. These
meteors are of medium velocity, at about 35 km per second. For a map
showing the movement of the radiant over time, check out
http://www.imo.net/calendar/cal02.html#Geminids.
The Zenithal Hourly Rate (ZHR) for the Geminids is about 120 meteors per
hour. This refers to the average number of meteors that an observer would
expect to see if they were out under a dark country sky, and if the radiant
is directly overhead. Geminid meteors tend to be fairly bright, with many
about the magnitude, ie. brightness, of the stars in the Big Dipper. For
experienced and novice observers alike, it is an impressive shower. Dress
warmly though - the nights are long and can be rather cold!
According to legend, the Gemini twins were Castor and Polydeuces, twin sons
of Leda and Zeus, who had disguised himself as a swan. Leda gave birth to an
egg, and the twins were hatched. Helen of Troy was their sister. Castor
was known for his skills in taming horses. Polydeuces was known for his
boxing. They both accompanied Jason and the Argonauts in their voyages, and
were considered rather blessed when a particular storm ceased with them on
board, and stars appeared around their heads. They became known as the
patron deities of seamen and voyagers. After the travels of the Argonauts,
Castor was slain in battle and Polydeuces was inconsolable. Zeus placed
both of them among the stars as Gemini the twins.
The parent body of the Geminid meteor shower is generally believed to be the
asteroid Phaethon. Some researchers say that Phaethon is the largest
remnant of the parent of the Geminid meteoroid stream, and that it is still
unclear as to what the true parent body is.
Phaethon is also in legend. He was the son of Clymene and Helios, the god
of the Sun. He didn´t meet his father until many years later. He asked his
powerful father for a favor - and Helios granted it. Phaethon had asked to
drive his father´s, the Sun-god´s, chariot across the sky. However, he
couldn´t control the powerful immortal horses, and destruction followed the
chariot. When it passed too close to the earth, the ground was burned.
Helios couldn´t stop his son, so Zeus threw a thunderbolt at Phaethon, and
killed him to save the earth. Phaethon´s body fell into the Eridanus river.
His sisters, who mourned him, were turned into trees and their tears into
amber.
For observers interested in recording data on the Geminids for the meteor
researchers, take a look at our NAMN Observing Guide at
http://www.namnmeteors.org/guide.html. The information to record while
observing includes such items as the time the meteor occurred, its magnitude
(brightness), the shower it belongs to, its 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.
A set of 4 star maps that you can use while observing - to mark the radiant
on, and with magnitudes of ´standard´ stars marked - can be printed off from
our website at
http://www.namnmeteors.org/charts.html. Any questions on
what to record, or how, can be sent to our NAMN Coordinator at
meteors@comcast.net
The IMO states that the Geminids are "one of the finest annual showers
presently observable." Dress warm, and get out to take a look at this
debris from the asteroid Phaethon!
2. Other December Activity...
Actually December has a lot of active showers - if you haven´t already
printed off a set of our 4 star maps to mark your radiants on, now would be
a good time. Set your printer to ´landscape´ mode and print them off from
http://www.namnmeteors.org/charts.html
The chi Orionids (XOR) reach a maximum on December 2nd with a radiant at 82
degrees, ie RA 05 hr 28.2m, Dec +23, which is about 5 degrees south of beta
Tauri. They can be seen until about December 15th. These are slow meteors
with a velocity of about 28 km per second. ZHR rates at maximum are about 3
meteors per hour. A map showing the radiant can be found at
http://www.imo.net/calendar/cal02.html#chi-Orionids
The December Phoenicids (PHO) peak on December 6th at 20:30 UT, but can
be seen from the start of the month until about the 9th. The radiant at
maximum will be at 18 degrees, ie. RA 01h 12m, Dec -53, which is roughly 35
degrees down to the left of beta Cetus - so this is a shower for more
southerly observers. These are slow meteors with a velocity of 22 km per
second. ZHR rates at maximum are variable, usually only about 3 meteors per
hour or less - but they did reach about 100 meteors per hour back in 1956.
A map showing the radiant can be found at
http://www.imo.net/calendar/cal02.html#Phoenicids
The Puppid-Velids (PUP), also mainly for southerly observers, reach a
maximum about December 7th but can be seen from the start of December until
about the 15th. The radiant at maximum will be at 123 degrees, ie. RA 08h
12m, Dec -45, which is about 17 degrees down to the left of the star eta
Canis Major. These are average velocity meteors at about 40 km per second.
ZHR rates are about 10 meteors per hour. The IMO states that "the activity
is so badly-known, we can only be reasonably sure that the highest rates
occur in early to mid December...most Puppid-Velid meteors are quite faint,
but occasional bright fireballs notably around the suggested maximum here,
have been reported." Observations are encouraged.
The Monocerotids (MON) reach a maximum on December 9th, and can be seen from
the beginning of December until about the 17th. Apparently telescopic
results suggest a later maximum, around December 16th. The radiant on the
9th is at 100 degrees, ie. RA 06h 40.2m, Dec +08, which is just south of the
left foot of Gemini. These are average velocity meteors at about 42 km per
second. ZHR rates are low, about 3 meteors per hour at maximum. This
shower is believed to possibly be the source of many of the spectacular
fireballs of the eleventh century. Many of these are documented in the
writings of Ma Touan-lin, a historian of the pre-Mongolian era, who
collected observations of over 1500 fireballs going back over 24 centuries.
A map of the radiant can be found at
http://www.imo.net/calendar/cal02.html#Geminids.
The sigma-Hydrids (HYD) reach a maximum on December 12th, but can be seen
from about the 3rd to 15th. The radiant on the 12th is at 127 degrees, ie.
RA 08h 28.2m, Dec +02, which is off to the left of Procyon in Canis Minor,
south of the little circlet of stars at the top of Hydra. These are fast
meteors with a velocity of about 58 km per second. ZHR rates are low, with
about 2 meteors per hour at maximum. A map of the radiant can be found at
http://www.imo.net/calendar/cal02.html#sigma-Hydrids.
The Coma Berenicids (COM) have a maximum on December 20th, but last from
about December 12th to January 23rd. The radiant at maximum is at 175
degrees, ie. RA 11h 40.2m, Dec +25, which is about 10 degrees north of the
bright star Denebola in the triangle of Leo. These are fast meteors at
about 65 km per second. ZHR rates are about 5 meteors per hour at maximum.
According to the IMO, "this shower is almost unobservable from the southern
hemisphere, so northern watchers must brave the winter cold to improve our
knowledge of it, especially this year as its expected peak benefits from a
nearly-new Moon." A map of the radiant can be found at
http://www.imo.net/calendar/cal03.html#Coma-Berenicids
The Ursids (URS) reach a peak on December 23rd at about 1h UT. They can be
seen from about December 17th to 26th. At maximum, the radiant is at 217
degrees, ie. RA 14h 28.2m, Dec +76, which is just above the pointer stars of
Ursa Minor, the Little Dipper. These are average velocity at about 33 km
per second. ZHR rates at maximum are about 10 meteors per hour - but on
occasion, rates have surged to about 50 meteors per hour! The IMO states
that "all forms of observation can be used for the shower, since many of its
meteors are faint, but with so little work carried out on the stream, it is
impossible to be precise in making statements about it." Observations are
encouraged! A map of the radiant can be found at
http://www.imo.net/calendar/cal03.html#Ursids
Lastly, the Quadrantids (QUA) need special mention - for those of you who
may be going away for the holiday season. The Quadrantids can be seen from
about January 1st to 5th, but reach a maximum on January 4th at about 6h UT
for visual observers according to the IMO. It is a sharp maximum - so
geographic location plays a role in the rates that you will see. These are
average velocity meteors at about 41 km per second. ZHR rates at maximum -
and only for a handful of hours - are about 120 meteors per hour. The
radiant at maximum is at 230 degrees, ie. RA 15h 19.8m, Dec. +49, which is
in northern Bootes. A map can be found at
http://www.imo.net/calendar/cal03.html#Quadrantids.
Besides recognized main showers and other minor showers, there is also
sporadic meteor activity in December. 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:
Mon. Dec. 8 full moon
Tues. Dec. 16 last quarter
Tues. Dec. 23 new moon
Tues. Dec. 30 first quarter
Planets at midmonth, and their magnitudes, for northern observers, are:
Mars -0.2 in Pisces
Saturn -0.3 in Gemini
Jupiter -2.1 in Leo
Venus -3.9 very low in west in evening
The planets are very good standards for estimating the magnitude of bright
meteors. For a map showing the planets´ positions in your sky, go to
http://www.heavens-above.com and Select your location, then go to ´Whole
Sky Chart´.
3. Christmas Ideas for Meteor Observers...
Need some hints to drop for Christmas gift ideas? Print the following
suggestions off, and leave them where Santa can find them:
... Membership in the International Meteor Organization (IMO): includes a
great bimonthly publication, very readable for the serious amateur. Send
check or money order payable to "Mr. Robert Lunsford" to Mr. Robert
Lunsford, IMO Secretary-General, 161 Vance Street, Chula Vista, CA 91910,
U.S.A. Cost: $20 U.S. for regular membership, with newsletter by surface
mail. More info can be found at
http://www.imo.net
... Book on meteors... good one is "Meteors" by Neil Bone, available through
Sky Publishing, website at
http://skyandtelescope.com. Cost: $24.95 U.S.,
currently on sale for $19.95 U.S.
... Also from Sky and Telescope... rather cute item, car license plate frame
with "Stars Up, Lights Down". Cost: $9.95 U.S. For every one sold, Sky
Publishing donates $3 U.S. to the International Dark Sky Association to help
raise awareness internationally about saving our night sky. For membership
in the International Dark-Sky Association, check out
http://www.darksky.org
... Also from Sky and Telescope... Wil Tirion´s Bright Star Atlas 2000.0, a
good paper atlas for visual meteor observers, or new observers wanting to
learn the sky better. Shows stars down to magnitude 6.5. Cost: $9.95
U.S., most reasonably priced basic star atlas around.
... If you´re into gadgets, the following can be useful for meteor
observing... a talking clock or watch (available at institutes for the
blind)... a small tape recorder for recording meteors... a pocket radio to
keep you company...
... And of course, the perennial favorite.... warm socks! Hey, this is
winter. If you want to observe, ask Santa for some nice warm clothes!
Merry Christmas to all, and don´t forget to put out cookies for Santa before
you head out observing on Christmas Eve!
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.
August 16-21, 2004, London, Ontario, Canada...
Meteoroids 2004 will be held in eastern Canada, at the University of Western
Ontario in London. Experimental and observational methods discussed will
include optical observations of meteors including ground-based visual,
photographic, video, and telescopic techniques, satellite observations of
meteors in various passbands, measurements of meteoric atoms in the
atmosphere by lidars and other techniques, acoustic measurements using
infrasound and seismic detection techniques, radio detection of meteors
including VLF and ELF, meteor and large aperture radar observations, and
observations, in-situ satellite and laboratory measurements of dust and
meteorite material. Scientific areas discussed will include such topics as
dynamics of sporadic, shower and interstellar meteoroids, physics and
chemistry of meteoroids and their interaction processes in the atmosphere,
fireball and bolide phenomenology, mineralogy of extraterrestrial materials,
hypervelocity impacts on spacecraft, meteoroid models and flux, and
interrelation of meteoroids, meteorites, IDP´s, asteroids and comets. To
receive further announcements directly on this, email meteoroids2004@uwo.ca.
The website for the conference is at
http://www.uwo.ca/meteoroids2004
For more information on upcoming astronomy meetings, see: "International
Astronomy Meetings List" at
http://cadcwww.hia.nrc.ca/meetings
5. For more info...
NAMN email: namn@atmob.org
NAMN website:
http://www.namnmeteors.org
Mark Davis, meteors@comcast.net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network
Cathy Hall, chall@cyberus.ca
Metcalfe, Ontario, Canada
Writer, NAMN Notes
Lew Gramer, dedalus@alum.mit.edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, ´MeteorObs´
Kevin Kilkenny, namnfireball@earthlink.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.mit.edu
Here´s to ´Clear Skies´ for December
... and a ´Merry Christmas´ to all
December 2003 NAMN Notes
... from Davis and Hall :)