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(meteorobs) NAMN Notes: May 1999
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NAMN Notes: May 1999
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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://web.infoavedot net/~meteorobs
Contents:
1. May brings the Aquarids...
2. Other May Showers...
3. Some Useful Websites for Meteor Observers...
4. Meteor Use in Ancient Times...
5. Upcoming Meetings...
6. For more info...
1. May brings the Aquarids...
The eta Aquarids (ETA) reach a maximum on May 6th this year, actually,
between 10h UT on the 5th and 11h UT on the 6th, just before last quarter
moon. The radiant at that time will be at 338 degrees, ie. RA 22h 32m,
Dec -01, very near the star eta Aquarius. The ZHR, zenithal hourly rate, at
maximum is about 60 meteors per hour with the naked eye, although a rate of
110 per hour was noted in 1980 in Australia. These are fast meteors, at
about 66 km per second. Shower members will be visible until about May 28th.
This is a very good shower for southerly observers, but not as favored for
those of us in the northern hemisphere due to the low elevation of the
radiant in the morning sky. As a result, rates for northern observers will
be much lower than for those further south, even before taking moonlight
into account.
The parent body of the eta Aquarids is Halley's Comet. The meteor shower was
first noted back in the 8th century in China. The sister shower produced by
Halley's Comet is the Orionids of October. The eta Aquarids that were seen
around the 1985-86 appearance of Halley's Comet seem to have been a bit
brighter than the average eta Aquarids seen most years, which have been
about magnitude +3.00.
This meteor stream, consisting of both showers, is sometimes called the
'Halleyids'. It was one of the first meteor streams to be detected by
radio-echo techniques. The radar equipment at the Springhill Meteor
Observatory in Ottawa, Canada was used for many years to gather data on this
stream. From 1958 to 1967, rates detected were typically between 350 and 500
meteors per hour. They found that the rates varied though, often with high
rates over several days, separated by a lull. This led researchers to
believe that there were filaments of material in the old comet orbit, with
higher rates when we encountered these in the several days around maximum.
This holds for both sister showers - the eta Aquarids, and the Orionids. The
Springhill data also found a smaller variation in rates from year to year
for the eta Aquarids.
Olivier, in his book Meteors talked about the difference between the
original comet orbit and the path of the meteors produced: "It is of great
interest to see how far from the comet's orbit some of these meteors
actually move. This distance was computed to be as great as 11,000,000 miles
for May 11, 1910. It should likewise be noted that the meteors were still
coming in 1913 in nearly as great numbers as in 1910, when the comet was
nearest the earth. We can have no better example of the process of slow
disintegration of a large comet into a meteor stream..."
2. Other May Showers...
The Sagittarids (SAG) continue to be active in May, and will continue until
mid-July. The radiant on May 20th will be at 247 degrees, ie. RA 16h 28m,
Dec -22, about 4 degrees north of the star Antares in Scorpius. However,
there is no specific date of maximum activity. The ZHR rates are generally
low, about 5 meteors per hour, but have occasionally reached a rate of 10
per hour. These are medium velocity meteors, at about 30 km per second.
This shower is part of the ecliptic activity, and due to its early May
radiant near Antares, the bright reddish star of the Scorpion, they are
often called the alpha Scorpiids. This shower has been associated with
fireballs, even in old historical references dating back to 354 A.D. It is
believed that the Sagittarids may be the debris of several parent bodies, as
yet undetermined.
There are a number of other very weak minor showers in the month of May,
although they are not included by the International Meteor Organization in
their 1999 "Working List of Visual Meteor Showers." The weak minor showers
have so few meteors that, unless an observer plots very diligently, it would
be difficult to determine whether a meteor belongs to a particular shower or
not.
If you want an interesting read, and some further information on these very
minor showers, check out Gary Kronk's 'Comets and Meteor Showers' webpage,
which has just recently moved to: http://comets.amsmeteors.org. There you
will find all kinds of information on showers detected by radio and
photographic means, and learn just how valuable plotting can be! Under the
month of May, there are all kinds of neat, obscure showers - like the
epsilon Aquilids, detected by radio, with a parent body in an Aten-class
asteroid orbit - and no apparent visual observations in the last 150 years!
Of special note to radio meteor observers are his notes on the daytime
showers of May - epsilon Arietids (max May 9th 18h UT per IMO), May Arietids
(max May 16th 19h UT per IMO), and omicron Cetids (max May 20th 17h UT per
IMO), and finally later in the month, the start of the Arietids and the zeta
Perseids.
Although the Arietids are a daylight stream with a maximum on June 7th 21h
UT, and the zeta Perseids a daylight stream with a maximum on June 9th 20h
UT, there have been some isolated reports of visual sightings of these
meteors - in the hours soon after sunset and soon before sunrise. They are
both strong showers, with rates of about 60 meteors per hour for the
Arietids at maximum in early June, and 40 per hour for the zeta Perseids at
maximum. Both showers start with much lower rates in late May. If you see
any unusual meteors coming up from the horizon, try to plot them!
For help in judging magnitudes of any brighter meteors this month, the
following are the magnitudes of some of the planets visible:
Venus: -4 in the evening sky
Mars: -1.6 on May 1, -1.5 on the 11th, -1.3 on the 21st
Jupiter: -2 in morning twilight in the last half of May
3. Some Useful Websites for Meteor Observers...
How to find out information on meteor observing:
North American Meteor Network:
http://web.infoavedot net/~meteorobs
American Meteor Society:
http://www.amsmeteors.org
International Meteor Organization:
http://www.imodot net
How to get more info on major and minor showers:
Gary Kronk's Comets and Meteor Showers:
http://comets.amsmeteors.org
How to find an astronomy club in North America nearest to where you live:
http://www.aspsky.org/html/resources/amateur_no.am.html
(on the Astronomical Society of the Pacific webpage)
How to check out viewing sites in the U.S. for light pollution:
http://proxima.astro.virginiadot edu/~ida/darksky
(on the International Dark-Sky Association webpage)
How to tell whether the skies will be clear for observing:
http://www.weather.com/weather/maps
(on the Weather Channel webpage)
How to convert time zones and get UT for your observing site:
http://www.timezoneconverter.com
(thanks to Gaétan Chevalier of Sainte-Foy, Québec for telling us of this
one!)
How to find out what your sky will look like on a given night:
http://www.fourmilab.ch/yoursky
(Your Sky, an interactive planetarium on the web)
How to find out your limiting magnitude:
http://www.seds.org/billa/lm/rjm.html
(on the Students for the Exploration and Development of Space webpage,
adapted from the original on the Finnish Amateur Astronomy Homepage)
How to find out what satellites you will see:
http://www.gsoc.dlrdot de/satvis
(German Space Operations Centre Satellite Predictions)
How to keep warm while observing (even in summer):
http://www.skypub.com/tips/tricks/keepingwarm.html
(on the Sky and Telescope webpage)
Where to find books on meteors to further your knowledge:
Knollwood Books:
http://www.meteorite.com/knollbks.htm
Martin Horejsi's Meteorite & Tektite Books:
http://www.meteorite.com/Martin_Horejsi.htm
Where to learn all about meteorites and impacts on the web:
Meteorite and Impacts Advisory Committee to the Canadian Space Agency:
http://dsaing.uqac.uquebecdot ca/~mhiggins/MIAC
The Meteorite Market webpage:
http://www.alaskadot net/~meteor
Where to get pictures and information on craters all over the world:
http://gdcinfo.agg.emrdot ca/crater/world_craters.html
(Database of Terrestrial Impact Structures, on the Natural Resources Canada
webpage)
Where to view various astro movies, including the Peakskill fireball:
http://image.gsfc.nasadot gov/poetry/movies/movies.html
(Movies and Animations from NASA and Elsewhere)
4. Meteor Use in Ancient Times...
The following exerpts are from an article in 'Meteor News' back in 1976, and
add a little whimsical note to our observations of the ecliptic activity in
Scorpius this month...
"In old Mesopotamian texts there are numerous passages that speak of
divination or fortune-telling, by observing shooting stars. The following
passages are from "Miscellanea Assyriaca IV", Babyloniaca, Vol. 7, 230 ff
1913-23, by S. Langdon and Publication 12, Center for Meteorite Studies,
Tempe, Arizona. It is assumed that the person doing the divination is
watching either the Wagon Star (Ursa Major), or Scorpio...
If in Scorpio a (shooting) star flashes and moves to the western end: there
will be rain in that month. If two (shooting) stars in Scorpio flash and
move to the western end: it will rain twice that month... if three... it
will rain thrice in that month.
If in the Wagon Stars a (shooting) star flashes and Jupiter rises: the
prince will be captured in defeat and go forth captive; his possessions will
be plundered from the palace.
If from above the Wagon Star a meteor flashes and like greenish lapis lazuli
passes to the right of a man: that man will attain unto long life... to the
left of a man: that man will be cast down.
If a meteor comes from above the Wagon Star and passes at the right of the
man like a golden bursu: that man will acquire wealth... at the left of the
man: that man will be cast down.
If a meteor comes from above the Wagon Star and is bloodstained and passes
at the right of the man: the man will see injury... at the left of the man:
that man will see the distress of his adversary.
If a meteor comes from above the Wagon Star and is dark and passes at the
right of the man: that man will see injury... at the left of the man: that
man will see the distress of his adversary.
If a meteor comes from above the Wagon Star and that meteor is (as if) dyed
red and passes at the right of the man: that man in that same year will be
slain... at the left of the man: he will be happy."
On a more analytical note, it appears from this that the ancients did note a
variety of colours in meteors, although in modern times we usually associate
la pis with a rich blue colour. The word bursu is probably related to the
Greek word bursa, meaning purse, in this reference, probably like a gold
coin colour. It is interesting that they refer to several different shades
of red for meteors, ie. bloodstained, and dyed red, which is probably
brighter. They also refer to dark meteors, an unusual reference, without
light or colour.
You just never know what interesting comments can be found in historical
references, even when the intent was not to relay scientific information!
5. Upcoming Meetings...
May 11-13, 1999:
The Leonid Meteoroid Storm & Satellite Threat Conference is being held in
Manhattan Beach, California. For more information, please contact
leonid-conf@aero.org or check out the website at:
http://www.aero.org/conferences/leonid. Papers are solicited in many areas,
including UV, optical, IR and radar observations of the 1998 Leonid storm;
dynamics, composition, occurrence of the Leonid meteoroids; and orbital and
meteoroid dynamics: 1997-2000.
July 15-18, 1999:
Starfest, Canada's largest amateur astronomical convention, is being held
near Mount Forest, Ontario. This is an camping event, with observers
bringing tents and telescopes. There are a number of special talks this year
on meteors, meteorites and comets. Dr. Peter Brown will talk on 'Prospects
for a Leonid Meteor Storm in 1999'. Phil Gebhardt will give a talk on 'Radio
Observations of Meteors'. Dr. Richard Herd, Curator of National Collections
at the Geological Survey of Canada will give a presentation 'Meteorites',
and discuss Canadian meteorite research and recovery. Dr. Paul Chodas,
Research Scientist at NASA's Jet Propulsion Laboratory will give several
presentations: 'Calculating Orbits for Asteroids and Comets' and 'Predicting
Comet and Asteroid Impacts'. For more info, and full program details, visit
the website of the NYAA, North York Astronomical Association, at:
http://www.interlog.com/~nyaa
July 26-30, 1999:
The Asteroids, Comets, Meteors 1999 Conference is being held at Cornell
University, near Ithaca, in New York State. Details are available at their
website: http://scorpio.tn.cornelldot edu/ACM. Although this is a professional
conference, a number of North American amateurs are planning to attend.
(NAMN members planning to attend, please also advise Mark Davis, NAMN
Coordinator, at MeteorObs@charlestondot net.)
August 7-15, 1999:
The 16th annual Mount Kobau Star Party, MKSP '99 will be held in southern
British Columbia, Canada, with talks and events on August 12, 13 & 14. Guest
speakers will include meteor researcher Dr. Martin Beech, a member of the
Canadian Leonid Team which sent an expedition to Mongolia last November. Dr.
Beech, will talk on Meteor Storms, Past, Present, and Future. Other speakers
include Gary Seronik from Sky & Telescope, Edmonton deep sky observer Larry
Wood, and astronomers from both the Dominion Radio Astrophysical Observatory
in Penticton and the Dominion Astrophysical Observatory in Victoria. For
more information, check out the website at http://www.bcinternet.com/~mksp
or contact the President of the Mount Kobau Astronomical Society, Jim
Failes, eij@bcinternet.com
September 23-26, 1999:
The 1999 International Meteor Conference (IMC), the annual conference of the
International Meteor Organization, is being held in Frasso Sabino, Italy.
The cost, including conference, lodging, and meals, is approximately $200
U.S. For more information, see the IMO website at http://www.imodot net
6. For more info...
Contact:
Mark Davis, MeteorObs@charlestondot net
Mt. Pleasant, South Carolina, USA
Coordinator, North American Meteor Network
And check out:
NAMN home page:
http://web.infoavedot net/~meteorobs
Back issues of NAMN Notes can be found on-line at the website.
To subscribe to the meteor email list or
To find out information on our weekly chat sessions:
Contact Lew Gramer at:
owner-meteorobs@jovian.com
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Here's to 'Clear Skies' for May!...
May 1999 NAMN Notes co-written
by Mark Davis and Cathy Hall
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