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(meteorobs) NAMN Notes: September 1999

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NAMN Notes: September 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. September Brings the Fall...
2. Possible Aries-Triangulids...
3. Help for Beginners...
4. Meteor Results from July...
5. 1999 South Georgia Perseid Results - by Kim Youmans
6. Upcoming Meetings...
7. For more info...


1. September Brings the Fall...

The month of September heralds the start of the fall season, for meteor
observers as well. The active summer showers have come and gone - the
Perseids, and all the many different Aquarid showers. The nights are
starting to cool off for those of us in the northern hemisphere, and
although the meteor rates have declined somewhat, the observing is still
very enjoyable.

There are only several showers active in September at rates easily
detectable by the unaided eye.

The alpha Aurigids (AUR) reach a maximum on September 1st, and can be seen
until about the 5th. These are fast meteors, with a velocity of about 66 km
per second. At maximum, the Zenithal Hourly Rate (ZHR) is about 10 meteors
per hour. On several occasions in the past though, rates have reached 3 to 5
times that number! The radiant, the location in the sky that the meteors
seem to come from, is at 084 degrees, ie RA 5h 36m, Dec +42, which forms a
nice triangle with alpha and beta Auriga - the stars Capella and Menkalinan.
These meteors are believed to be debris from Comet Kiess, C/1911 N1,
discovered by C.C. Kiess of the Lick Observatory on a photographic plate
taken with the Crocker Photographic Telescope. This comet has an elliptical
orbit with a period of about 2500 years!

The Northern iota Aquarids (NIA), although having reached a maximum on
August 20th, may be seen until the first day or so of September. These are
medium  velocity meteors, at about 31 km per second, and most are faint. The
radiant on August 30th was at 337 degrees, ie RA 22h 28m, Dec -5, which is
between the stars kappa and theta Aquarius.

The delta Aurigids (DAU) reach their maximum on September 9th, new moon, and
stretch from about September 5th to October 10th. At maximum, the ZHR rate
is about 6 meteors per hour. These are fast meteors, with a velocity of
about 64 km per second. The radiant on the 9th is at 060 degrees, ie RA 4h
00m, Dec +47, which is on the left arm of Perseus near the variable star MX
on a star atlas - and not in the constellation of Auriga at all. There is a
questionable link between these meteors and Comet Bradfield, C/1972 E1.

The Piscids (SPI) come to maximum on September 20th, but are visible all
month. These are slow meteors, with a velocity of about 26 km per second.
The ZHR rate at maximum is about 3 meteors per hour and the radiant on the
20th is at 005 degrees, ie RA 0h 20m, Dec -01...in the square of Pegasus,
follow a line from alpha Andromeda (Alpheratz) to gamma Pegasus (Algenib),
the left stars of the square, to a point about the same distance on a line
south. The radiant on the 20th is about 4 degrees further south than this
point.

For assistance in judging magnitudes of brighter meteors seen this month,
the following are the magnitudes of some of the brighter planets visible,
taken from the Handbook of the Royal Astronomical Society of Canada:

Start of month/11th/21st:
Venus (morning sky): -4.3, -4.5, -4.5
Mars (evening sky): 0.3, 0.4, 0.5
Jupiter (all night): -2.7, -2.8, -2.8
Saturn (all night): -0.2, -0.2, -0.3


2. Possible Aries-Triangulids...

Lastly, there is a minor shower in September that needs more attention in
order to determine its characteristics. It was discovered on September 12,
1993 by three American observers - Gary Kronk of Illinois, George Gliba of
Maryland, and Kurt Sleeter of Illinois. The following info is provided by
George Gliba:

"There is a good chance that the minor meteor shower, the Alpha Triangulids,
also known as the Aries-Triangulids, will put on their best showing since
being discovered in 1993, by three American meteor observers (Sky and
Telescope, October 1994)... That is because this stream is thought to be
periodic...

This minor meteor shower has shown very little activity since 1994, but last
year myself and a couple of Japanese meteor observers plotted several
meteors from the Aries Triangulum area. This may mean that the 5.5 to 6 year
period postulated by Kronk and Currie may be correct, and that enhanced
activity can be expected.

The maximum is probably sometime around September 12th. Still, if there is a
minor outburst, only five or six meteors per hour are expected. However,
surprises are not uncommon when you observe meteor showers; so it may be
better or worse than expected.

Observers are encouraged to try to plot any meteors seen from this minor
meteor shower, or better yet, to use a video system... Plotting, video,
radio, radar, and photographic methods of detection are all encouraged to
help to finally nail this minor periodic meteor shower down... The
conditions will be favorable, with a waxing crescent moon for the predicted
maximum, which occurs on a weekend!

Also, according to observations by three Italian meteor observers made two
years ago... the A-T meteors may start as early as late August, or early
September. Observers are asked to watch this minor meteor shower on as many
nights as possible, to help to define all of the characteristics it has."

According to last year's September issue of Meteor Trails, edited by Robert
Lunsford, the Aries-Triangulid radiant is at approximately RA 2h 00m Dec
+29, which is very near alpha Triangulum, the star called Metallah. This is
the radiant position listed by Kronk as being an average obtained from the
observations made in 1993.


3. Help for Beginners...

If you are new to meteor observing and would like to try recording data for
use by the meteor researchers around the globe, check out the NAMN website
at: http://web.infoavedot net/~meteorobs. The NAMN Observing Guide is an
excellent resource for information on how to get involved in observing
meteors - and making a valuable contribution to this field of science!

The NAMN Observing Guide has information for beginners on how to observe and
record meteors visually, or by photographic, telescopic or radio means. It
provides observing report forms, and sky charts to help in recording the
appropriate meteor data. There is also a special section on fireballs.

Under "Meteor Observing Target Dates for 1999", the NAMN site has a list of
showers visible throughout the year, with radiant locations listed in RA,
Right Ascension, and Dec, Declination. This means that you can pull out
your star atlas, and figure out easily where the various meteor shower
radiants are located.

The NAMN site also has useful links to other sites on the worldwide web -
such as the AMS, American Meteor Society: www.amsmeteors.org, and Gary
Kronk's wonderful site on comets and meteors: http://comets.amsmeteors.org

For more advanced technical information on all aspects of meteor observing -
including such topics as recording meteors with video equipment, and
computer simulations of meteor 'storms' - check out the website of the IMO,
International Meteor Organization, at www.imodot net


4. Meteor Results from July...

Even with their maximum in August, the Perseids were still the dominant
shower NAMN members observed in July. We normally consider the Perseids as
being active from July 17 to Aug 24 as you see frequently published, but
many observers have been reporting Perseids starting earlier. This year, the
first Perseid was reported by Pierre Martin on July 11 from Ontario, which
was the same start date reported in 1997 by Norman McLeod in Florida. Last
year the first Perseid waited till July 15 to appear. In all, only 48
Perseids were recorded this year in July, but it will be interesting to see
how this develops in the future.

Some of the other showers making an appearance this month included the
Aquarids, alpha Capricornids, Pegasids, Pisces Austrinids and Sagittarids.
The Pegasids were the next most active shower with 42 meteors reported. All
of the other streams that were monitored this month only produced small
numbers. The sporadics once again dominated with 730 being reported in July.

July was well covered with 18 mornings having one or more observer out.
Twelve observers submitted 78.56 hours of observations in July which were
forwarded to both the American Meteor Society and the International Meteor
Organization. We were also pleased to receive observations for the first
time from several people, and hope they will continue participating in our
meteor watches. For this period, reports were received from the following
people:

Jure Atanankov       Scott Moser
Wayne Hally          Eric Palmer
Javor Kac            Natasa Petelin
Robert Lunsford      James Smith
Michael Mattiazzo    Harry Waldron
Pierre Martin        Kim Youmans


5. 1999 South Georgia Perseid Results, by Kim Youmans

With all that data from the recent Perseid shower piling up on my desk, and
the moon reaching its full state, I decided to sit down and crunch a few
numbers. I herewith respectfully submit a brief outline of my Perseid
observations. Overall, weather wise, I was more fortunate than many on my
side of the Mississippi, with thick haze being my worst enemy on most
nights. But my rates were nothing short of pitiful--still, after watching
sporadics for most of the year, I had a great time, sleep or no sleep! I
enjoyed many small bursts of activity, including an early one on the night
of 9/10 at around 8:30UT. My LM's were right at 6.0 for local maximum, so I
didn't complain.

Time is Universal Time. PER is total Perseids per session. Teff is total
Teff per session. LM is the average limiting magnitude for the entire
session, regardless of # of hours. [OHR is the observed hourly rate -
Editor.] Sporadic activity has been omitted. I faced South or SE each night
at an elevation of about 65-80 degrees.
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08-01/02-99 2:05-3:12 PER(2) 1 period teff=1.0 LM=5.99 r=3.0
Avg OHR=2 OHR by period = p1(2) p2(2)

08-02/03-99 NO DATA

08-03/04-99 2:20-3:28 PER(2) 1 period teff=1.03 LM=5.28 r=2.5
Avg OHR=1.84 OHR by period = p1(2)

08-04/05-99 2:26-4:50 PER(4) 2 periods teff=2.0 LM=5.88 r=2.75
Avg OHR=2 OHR by period = p1(2) p2(2)

08-05/06-99 3:12-5:45 PER(5) 2 periods teff=2.19 LM=5.85 r=2.2
Avg OHR=2.32 OHR by period = p1(2) p2(3)

08-06/07-99 3:12-7:32 PER(8) 3 periods teff=4.12 LM=5.86 r=2.5
Avg OHR=1.88 OHR by period = p1(2) p2(2) p3(4)

08-07/08-99 4:45-6:18 PER(7) 1 period teff=1.38 LM=5.65 r=2.43
Avg OHR=5 OHR by period = p1(7)

08-08/09-99 NO DATA

08-09/10-99 6:20-9:11 PER(20) 2 periods teff=2.55 LM=5.88 r=2.45
Avg OHR=7.5 OHR by period = p1(6) p2(14)

08-10/11-99 6:45-9:30 PER(34) 2 periods teff=2.43 LM=6.06 r=2.65
Avg OHR=14.14 OHR by period = p1(15) p2(19)

08-11/12-99 5:15-9:07 PER(61) 3 periods teff=3.55 LM=6.03 r=2.51
Avg OHR=17 OHR by period=p1(15)p2 (19) p3(27)

08-12/13-99 4:09-9:16 PER(111) 4 periods teff=4.72 LM=5.99 r=2.28
Avg OHR=23.03 OHR by period = p1(9) p2(34) p3(27) p4(41)

08-13/14-99 5:08-6:12 PER(13) 1 period teff=1.03 LM=5.05 r=2.38
Avg OHR=12.58 OHR by period=p1(13)

08-14/15-99 NO DATA

08-15/16-99 NO DATA

08-16/17-99 6:42-7:50 PER(5) 1 period teff=1.08 LM=6.16 r=3.8
Avg OHR=4.6 OHR by period=p1(5)

08-17/18-99 NO DATA

08-18/19-99 6:39-9:27 PER(8) 2 periods teff=2.53 LM=6.19 r=2.75
Avg OHR=3.22 OHR by period = p1(4) p2(4)

08-19/20-99 NO DATA

08-20/21-99 NO DATA

08-21/22-99 7:29-9:45 PER(4) 2 periods teff=2.09 LM=6.22 r=2.75
Avg OHR=1.94 OHR by period = p1(2) p2(2)

Average OHR is derived from the number of Perseids per a given period
divided by the Teff for that period, all periods being averaged together for
the final result.


6. Upcoming Meetings...

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 www.imodot net

January 10-13, 2000:
The 38th annual Aerospace Sciences Meeting & Exhibit of the AIAA, American
Institute of Aeronautics and Astronautics, will be held in Reno, Nevada. A
special session on meteors has been proposed, called 'Aerothermochemistry
effects in meteoric plasmas' and will be chaired by meteor astronomer Dr.
Peter Jenniskens of The SETI Institute at NASA/Ames Research Center, and
co-hosted by plasma physicists Dr. Olga Popova of the Moscow Institute for
Dynamics of Geospheres RAS and Dr. Iain Boyd of the Department of
Aerospace Engineering of the University of Michigan. This is an opportunity
for the plasmadynamics, thermophysics, and fluid dynamics communities to
learn more about the physics, aerochemistry, and optical diagnostics of
meteoroids. Information on the conference can be found on the website at:
http://www.aiaa.org/calendar/asm00cfp.html.


7. 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 NAMN 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 September!...

September 1999 NAMN Notes co-written
by Mark Davis and Cathy Hall
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