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(meteorobs) NAMN Notes: May 2002

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NAMN Notes: May 2002
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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:
www.namnmeteors.org


Contents:

1. Edmond Halley - His Comet and Our Meteors...
2. Sagittarids, the Ecliptic Activity...
3. Other Sky Events in May...
4. Upcoming Meetings...
5. For more info...


1. Edmond Halley - His Comet and Our Meteors...

Edmond Halley is famous for many things - notably Halley's Comet! Our main
meteor shower in May is debris from this famous comet!

Who really was Edmond Halley though? Sure, we've heard about his comet...
but was it his comet? Not really. Halley - in the comet world - became
famous for realizing that the comets of 1531, 1607 and 1682 were all the
same body. He didn't discover any of them - but he was astute enough to
realize, by comparing their orbits, that they were the same. It was this
significant discovery that resulted in these comets being renamed as Comet
Halley! Nor was he the only astronomer to have a comet named after him due
to the calculation of the orbit. The wonderful 6-tailed comet of 1744 that
we all know as de Cheseaux's Comet wasn't found by de Cheseaux either. But,
it bears his name as he computed its orbit and made extensive observations
of it! And even the well-known Comet Encke was not found by Encke. It was
discovered by the famous comet hunter Jean Louis Pons! But Encke identified
it as a short period comet, orbiting the sun about every 3.3 years - and so
it was renamed Comet Encke!

But... back to Halley, the astronomer who didn't discover Halley's Comet.
What else is he known for? Well, he is well-known for quite a strange
variety of
reasons. He designed an underwater diving bell. He worked as deputy
comptroller for the English mint. He published the very first
meteorological map, showing prevailing winds over the oceans. He produced
one of the earliest studies of human mortality, which was quite influential
in the actuarial industry. He was a naval captain of a ship called the
"Paramore Pink", and sailed all over the Atlantic Ocean charting the
variation of the earth's magnetic field! He persuaded Newton to publish the
Principia Mathematica, and paid for the publishing costs out of his own
pocket.

Astronomically, besides the comet connection, he made many contributions.
He compiled the first systematic catalogue of stars in the southern
hemisphere. He was the first to recognize that stars move in relation to
one another. He noted that observing transits of Venus passing in front of
the Sun would make it possible to calculate the distance from the Sun to the
Earth. He became Astronomer Royal in Great Britain in 1720 and held the
post for 21 years, until shortly before his death at Greenwich in his late
80's.

So, it is with some interesting history that Halley's Comet brings us our
main meteor activity for the month of May!

The eta Aquarid (ETA) meteor shower reaches maximum activity on May 5th at
530 UT, Universal Time according to the International Meteor Organization.
This shower activity started in April, and will continue until about May
28th, with the maximum activity centered around May 5th and 6th.

These are fast meteors, with a velocity of about 66 km per second. ZHR
rates are quoted as about 60 meteors per hour. This is the number of
meteors per hour, on average, that an observer would expect to see with
the unaided eye, if they are 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. If your sky is light-polluted with city lights and
glare, you will not see as many meteors from Halley's Comet!

In their 2002 Meteor Shower calendar, the IMO writes about the eta Aquarids:

"A relatively broad maximum, sometimes with a variable number of submaxima,
usually occurs in early May. ZHRs are generally above 30 between about May
3-10, based on IMO observations during 1988-1997, analyzed by Tim Cooper,
and confirmed by visual and radio observation since... All forms of
observing can be used to study the eta-Aquarids, with radio work allowing
activity to be followed even from many northern latitude sites throughout
the daylight morning hours."

This is a shower that has, actually, quite good rates over a number of
days - and all observations are encouraged! If you are going to be clouded
out for the time of maximum activity, try to observe the nights before or
after the shower. This information is valuable to the researchers - in
order to get a better picture of the whole period of activity of this debris
from Halley's Comet!

Where do the meteors come from in the sky? Print off a map showing the
radiant (and its movement over time) from the IMO website at
http://www.imodot net/calendar/cal02.html#eta-Aquarids The radiant on May 5th
will be at 338 -01, ie RA 22h 31.8m, Dec -01, which is very near the star
eta Aquarius on a star atlas. The radiant is not a single spot, but an
area in the sky approximately centered on these coordinates.

If you want to learn more about how to record meteors so you can help out
the meteor researchers, check out our NAMN Observing Guide at
www.namnmeteors.org/guide.html If you have any questions, drop a note to
our NAMN Coordinator at meteors@comcastdot net

Clear skies for May.... and have fun observing the debris from Halley's
Comet!


2. Sagittarids, the Ecliptic Activity...

The Sagittarids (SAG) continue into May, and will last until about mid-July.
This is a complex of radiants near the ecliptic, and is believed to be the
debris from a number of unknown bodies. Most meteor showers are old comet
debris, and one well-known meteor shower (the Geminids, in December) is
actually asteroid debris - but the origin of the Sagittarids is unknown.

These meteors are almost slow, with a velocity of about 30 km per second,
and the ZHR rates are about 5 meteors per hour. Fireballs have been
associated with this shower - so those of you out observing could be
rewarded with some spectacular bright meteors!

The radiant of the shower - the area in the sky where the meteors seem to
come from - does move over time, as with all meteor showers. In the case of
the Sagittarids, spanning such a long time period (mid-April until
mid-July), the movement from week to week is quite pronounced. How do we
know where this radiant is from week to week? Print yourself off a copy of
Table 6 on the IMO website at http://www.imodot net/calendar/cal02.html#Table6

For example, for SAG, the Sagittarids, come from the following areas in the
sky:
May 5   236 -20
May 10 240 -21
May 20 247 -22
May 30 256 -23

So... what is this? These are coordinates, and you can read these positions
off our NAMN star charts. Print yourself off a set of 4 from
www.namnmeteors.org/charts.html The first number refers to Right Ascension,
ie longitude in the sky. The second number refers to Declination, ie
latitude in the sky.

If you already have a star atlas at home, how do you convert these
coordinates to what is on your (normal) star atlas? Well, divide the first
number (RA, Right Ascension) by 15 to get a whole number of hours, then
multiply the decimal remainder times 60 to get minutes. The Declination in
degrees stays the same.

example: May 5: 236 -20
236/15 = 15.73, so get 15 hours
then .73 x 60 = 43.8, so get 43.8 minutes
So, SAG radiant is at RA 15h 43.8m, Dec -20
which is readable off your star atlas!

Besides recognized main showers, other minor showers and even daytime
meteor showers, there is also sporadic meteor activity in May. 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.


3. Other Sky Events in May...

There are a lot of neat things in the sky in May, besides just meteors!
However, a bit of knowledge about these other objects will prove useful to
you, both in your meteor observing, and in your learning of the night sky.

In May, the moon phases are as follows:
Sat. May 4 - last quarter
Sun. May 12 - new moon
Sun. May 19 - first quarter
Sun. May 26 - full moon

For use in judging the brightness of the meteors you see this month, the
magnitudes of the planets are as follows, to the nearest half magnitude:
Venus -4 low in west
Mercury 0 on May 1, 1.4 by May 11, 3.8 by May 21, low in west
Jupiter -2 visible in Gemini, low in west
Saturn 0 low in west
Mars 1.5 low in west

As you can see, all of the bright planets are low in the west this month -
and will make for some great views! Try some photographs with camera and
tripod - it is not very often that we can see all these planets close
together in the sky. It is, of course, a view due to our perspective where
we're watching from, but quite interesting nonetheless. Use fast film,
with your camera on a tripod, with a cable release. Set your camera to B
(bulb setting), and do a series of time exposures, such as (for instance) 10
sec, 15 sec, 20 sec, up to about 35 seconds. Always bracket your
exposures like this... you have a much better chance of getting a perfect
shot. One important tip - if you are using a Skylight or other type of
filter on your lens to protect it, take it off during your exposures - or
due to the brightness of the planets, you will get ghost images of them
diagonally opposite their position in your photo!

The planets will appear very close to the moon during their dance from
night to night in the western sky. On Tuesday May 14th, there are 3
planetary occultations! This is where the moon passes in front of a planet,
as seen from earth. Saturn will appear to go behind the moon, as seen from
the British Isles, western Scandinavia, Greenland, the Arctic Ocean,
northern Canada, and northeast Asia. Mars will appear to go behind the
moon, as seen from the southeast Pacific Ocean, South America apart from the
far north and south, and the southwest Atlantic Ocean. Lastly, Venus will
appear to go behind the moon, as seen from the south Pacific Ocean.

For some great maps of the planetary positions this month, go to the Heavens
Above website at http://www.heavens-above.com On the main screen, go to
Select, pick your country and nearest city... then scroll down to Whole
Sky Chart. Pick your night and time... and you get a wonderful chart of the
whole sky to print off, showing where the planets are that night!

And... we still have at least one fairly decent comet around too! Comet
Ikeya-Zhang will be visible in binoculars in May. For a finder chart, go to
the Heavens Above site just mentioned, or Seiichi Yoshida's site, "Weekly
Information About Bright Comets" at
http://www.aerithdot net/comet/weekly/current.html To see some absolutely
stunning photos of Comet Ikeya-Zhang, go to Gary Kronk's "Cometography"
website at http://cometography.com/lcomets/2002c1.html Stay tuned to these
websites for more comet info... we seem to have a number of comets
accessible to amateurs lately!

There are a lot of interesting astronomical sights this year in May -
besides just meteors! Get outside, get reacquainted with the constellations
after a long winter, and let us know about your observations!


4. Upcoming Meetings...

May 2-5, 2002, Tokyo, Japan...
The 2002 Leonid MAC Workshop, an international science symposium on the
Leonid meteor storms, will be held in Tokyo. For more information, contact
Dr. Peter Jenniskens at pjenniskens@mail.arc.nasadot gov, and check out the
conference website at http://planetb.sci.isas.ac.jp/~avell/2002_Leonid_WS/

July 21-26, 2002, Los Angeles, California USA...
The 65th annual meeting of the Meteoritical Society will be held at the
University of California in Los Angeles. Special sessions planned include
'Mars: Meteorites and Missions' and 'Chondrule and CAI origins'. For
information, check out www.lpi.usradot edu/meetings/metsoc2002

July 29-August 2, 2002, Berlin, Germany...
The Asteroids, Comets, Meteors 2002 Conference will be held in Berlin,
Germany. Topics that will be covered include comets, asteroids, meteor
showers, interplanetary material, collisions and impacts, NEO's (near earth
objects), the asteroid-meteorite connection, transitional objects, origin of
comets, and many other related topics. This is the 8th ACM conference in a
series, with a conference being held only every 3 years. It is being
jointly organized by the DLR Institute of Space Sensor Technology and
Planetary Exploration, the Max Planck Institute for Aeronomy, and the
Technical University of Berlin. There is a registration discount if you
register before May 1st. For details, contact J. Benkhoff at acm2002@dlrdot de
and check out the ACM 2002 website at http://berlinadmin.dlrdot de/SGF/acm2002

September 26-29, 2002, Frombork, Poland...
IMC 2002, the International Meteor Conference, will be held in Frombork,
Poland - land of Copernicus! This is the annual conference of the IMO, the
International Meteor Organization, and welcomes all meteor observers, both
amateur and professional. The conference is organized by CMW, the Polish
Comets and Meteors Workshop. Besides the talks and discussions, there are
many interesting sites to visit, such as the tower where Nicolaus Copernicus
made many of his observations and the Radziejowski tower with its
astronomical planetarium. For information, check out www.imodot net and
www.astrouwdot edu.pl/~olech/pkim/imc2002/imc.html. For specific questions,
contact Mariusz Wisniewski at pkim@astrouwdot edu.pl

For more information on upcoming astronomy meetings, see:
"International Astronomy Meetings List"
http://cadcwww.hia.nrcdot ca/meetings


5. For more info...

NAMN email: namn@atmob.org
NAMN website: 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
Co-author, NAMN Notes

Lew Gramer, dedalus@alum.mitdot edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'

Kevin Kilkenny, Mail4Meteors@aol.com
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites

Back issues of NAMN Notes can be found on-line at the NAMN website
and in the MeteorObs archives at:
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

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Here's to 'Clear Skies' for May...

May 2002 NAMN Notes co-written
by Mark Davis and Cathy Hall

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