(meteorobs) NAMN Notes: September 2006

Sat Sep 2 17:08:03 EDT 2006

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NAMN Notes:  September 2006
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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.  September - Aurigids are Falling!...
2.  Aries-Triangulid & September Taurid Meteors... by G.W. Gliba
3.  Other Interesting September Events...
4.  Upcoming Meetings...
5.  For more info...

1.  September - Aurigids are Falling!...

It is hard to believe that it's September already.  For northern observers,
Orion is up in the morning sky and temperatures are starting to cool down
for the season.  September brings several meteor showers from the
constellation of Auriga.

In ancient myths and legends, Auriga is the Charioteer in the heavens.  He
is often known as Phaethon, the son of the sun god Helios.  Apparently
Phaethon asked Helios one day if he was really his son.  Helios replied "of
course I'm your father" and to prove it to his son, said "take the car for a
spin".  Well, the 'car' was a chariot led by flying horses, and Phaethon
lost control.  The chariot careened into the northern sky.  The god Zeus
hurled a thunderbolt to stop it - and Phaethon was killed by the lightning
as well.  So... Phaethon was put into our northern sky as Auriga, the
Charioteer.  Lousy driver, but neat constellation!

The alpha Aurigids (AUR) peak on September 1st at about 6h30m Universal Time
(UT) according to the International Meteor Organization (IMO).  For
observers in eastern North America, this means about 2.30 a.m. EDT.  They
run through until about September 8th.

These are fast meteors, with a velocity of about 66 km per second.  ZHR
rates will be about 10 meteors per hour (according to the table on the IMO
calendar).  ZHR refers to Zenithal Hourly Rate, and is the number of meteors
that an observer would expect to see, on average, if they were out observing
in a dark country sky, and if the radiant, the area in the sky where the
meteors seem to come from, is directly overhead at the zenith. Where is the
radiant?  Check out the map at
http://www.imo.net/calendar/2005/summer#alpha-aurigids

This shower can bring some surprises.  The alpha Aurigids had short
unexpected bursts of about 30-40 meteors per hour in 1935, 1986 and 1994.
Observations are encouraged - and not just on the peak night.  Surprises can
occur on other nights.  Get out and take a look!

The delta Aurigids (DAU) peak on September 9th and run from about September
5th through until October 10th.  These are also fast meteors, at about 64 km
per second.  ZHR rates at the peak will be about 5 meteors per hour.  A map
of the radiant is available at
http://www.imo.net/calendar/2005/summer#delta-aurigids

According to the IMO:

"The delta-Aurigids probably represent a combination of two separate, but
possibly related, minor sources, the September Perseids and delta-Aurigids,
whose activities and radiants effectively overlap one another.  The showers
are not resolvable by visual watchers, who are advised <to use the September
9th peak date and radiant info>, although these primarily derive from the
'September Perseid' phase.  The 'delta-Aurigid' phase seems to give a weak
maximum around... September 24."

All types of observations are encouraged - including telescopic,
photographic and video - in order to learn more about this shower.  Try
something different this September!  Get out your telescope, or try some
guided photographs.

For visual observers, NAMN has a set of 4 star charts to help you judge the
brightness (magnitude) of the meteors you see.  They are also a great tool
for new observers to help you learn your constellations better.  The charts
can be printed off from http://www.namnmeteors.org/charts.html.  Set your
printer to landscape mode.

If you want to record visual data for the meteor researchers,
check out our NAMN Observing Guide for information on what to record.  Our
Guide can be found at http://www.namnmeteors.org/guide.html.  We record such
info as the time a 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.  If you have any questions, drop a note to our NAMN Coordinator at
meteors at comcast.net

Forms to record your observations can be found at
http://www.namnmeteors.org/namn_form.html and
http://www.namnmeteors.org/appendixC.html

For those of you interested in plotting your meteors (recommended for
serious observations), special IMO plotting maps can be ordered through
Robert Lunsford of the International Meteor Organization.  For details,
contact him directly at lunro.imo.usa at cox.net

To read up further on telescopic, photographic and video recording of
meteors, check out the IMO website at http://www.imo.net

2.  Aries-Triangulid & September Taurid Meteors... by G.W. Gliba

The maximum for the Aries-Triangulid (ie. alpha Triangulid) minor meteor
shower is on September 12th or 13th.  There is some historical evidence that
this stream may be periodic, and/or have several submaxima.  More
observations are always needed.

The primary radiant is near alpha Trianguli, with a possible secondary
radiant located further south near the 2nd magnitude star Hamal (alpha
Arietis).  The alpha Trianguli radiant is usually most active around
September 10th to 14th.  However, there is some evidence, from Italian
meteor observers, that the Aries radiant may be most active in late August
and early September.  This year the moon will be a waning gibbous near the
September maximum, which will make it difficult to see any activity,
which is expected to be light, but surprises are still possible.

Historically, this shower seems to have a period of 5 or 6 years, according
to comet & meteor researcher Gary W. Kronk.  The years when two or more
meteor observers saw good activity visually were 1934, 1940, 1951, 1993,
and in 1998 and 1999.  In 2004, some activity was seen by several observers,
but significant activity was reported by only one observer, which may have
been a short lived outburst of mostly faint meteors.  More observations are
needed to establish the periodic nature of this meteor stream.

Very little activity was seen last year, but some activity has been reported
every year since this meteor stream was first discovered to be possibly
annual thirteen years ago.  However, some of this activity is probably due
to chance alignments of sporadic meteors with the radiants.

The September 2004 Sky & Telescope magazine had an article on the September
Taurid shower, which is a possible minor meteor shower which peaks
near September 14th.  However, there is more controversy as to its existence
than the above shower due to its close proximity to the northern and
southern apex meteor sources, which are nearby, and thus a source of meteor
pollution.  The possible radiant for the September Taurids is located
between the Hyades and Pleiades star clusters.  The jury is still out on
this shower.  If real, it may also be periodic in nature.

In 2003, WGN (originally Werkgroupniews), the Journal of the IMO, 31:3
(2003), an article on the existence of this reputed minor meteor shower
explains that according to Arkadiusz Olech, visual meteor data from the
Polish Comets and Meteors Workshop group shows no trace of September Taurid
meteors from 1996 to 2000.  They do mention another less plausible
explanation, that this meteor shower might be real but not present during
1996-2000.  Interestingly, the Polish Comets and Meteors Workshop data
mentioned in this article clearly shows activity from the Aries-Triangulum
area!

September is one of the months with the highest rates for sporadic meteor
activity.  This will always make it difficult, if not impossible, to resolve
these types of minor meteor showers for most years.  However, during any
year when enhanced activity occurs, they can then be separated from the
sporadic background.  So, it is important to monitor these minor meteor
radiants, and others, each year, to watch for any increase in activity that
may happen.  Even negative observations are important.

(Thanks to George Gliba for providing details on these minor showers.
Although many observers concentrate on the showers listed on the
International Meteor Organization's "Working List", new research is always
encouraged - and welcomed.  Questions can be directed to George Gliba at
gliba at milkyway.gsfc.nasa.gov.)

3.  Other Interesting September Events...

The Piscids (SPI) reach a peak on September 20th and can be observed for
the whole month of September.  These are fairly slow meteors, with a
velocity of about 26 km per second.  ZHR rates at the peak will be about 3
meteors per hour.  A map of the radiant can be found at
http://www.imo.net/calendar/2006/summer

And what's the myth behind Pisces, the fish?  Apparently Aphrodite, the
goddess of love, and her son Eros, were out on the shores of the Euphrates
River one afternoon, when the huge monster Typhon appeared.  Typhon had a
hundred heads that spouted fire, and a body covered in snakes.  Aphrodite
and Eros dashed into the river and turned themselves into fish to escape.

The Sextantids, a daytime meteor shower normally detected by radio
observers, could yield some visual meteors.  The radiant is at 152 degrees,
ie. RA 10h 7.8m, Dec +0.  The peak is expected on September 27th at 16h UT,
but may occur a day earlier.  In 1999, strong activity was noted on the
29th, and in 2002, a peak occurred around the 29-30th.  This shower runs
from about September 9th to October 9th.

And Sextans?  This constellation comes not from myth, but from Johannes
Hevelius (1611-1687), a brewer by trade, and an astronomer and instrument
maker by passion.  His patrons were Jan III Sobieski, the King of Poland and
Louis XIV of France.  He built himself a private observatory named
Stellaeburgum and published an atlas of the heavens called "Firmamentum
Sobiescianum".  The constellation Sextans Uraniae is named after the brass
sextant he and his wife used to measure angular distances of stars, and
Sobieski's Shield (also known as Scutum) is named after his patron.

Other accomplishments?  Hevelius published the first lunar atlas, called
"Selenographia" and named the flat areas maria.  He wrote a major book on
instrumentation - "Machina Coelestis" and introduced the vernier scale.  He
prepared a catalogue of 1,564 stars, and was one of the first to observe a
transit of Mercury.  He discovered a number of comets.  A very nice
engraving from the "Firmamentum" of Hevelius presenting his sextant and
Sobieski's shield to Urania, the goddess of astronomy, can be found at
http://www.bo.astro.it/~biblio/Vultus-Uraniae/Volto_fig06.html

To learn more about the constellations, check out the Hawaiian Astronomical
Society's Storybook and Deepsky Atlas at http://www.hawastsoc.org/deepsky

For other September minor showers not on the International Meteor
Organization, "Working List of Visual Meteor Showers", and for a wealth of
historical information on all showers, check out Gary Kronk's 'Comets and
Meteor Showers' website at http://comets.amsmeteors.org

Besides September's main activity, and other minor showers, there is also
sporadic meteor activity.  This sporadic meteor activity is about 7 meteors
per hour visible to the unaided eye.  Some of these are random, and some
belong to old untraceable meteor showers.

Planets at midmonth, and their magnitudes, for northern observers, are:
Venus        -3.8  very low in east-northeast in morning twilight
Jupiter      -1.8  in Libra, very low in west-southwest in evening twilight
Saturn        0.5 in Leo, low in east in morning twilight
For observers around the globe wanting to check out our (remaining!)
planets, note that on September 7th Uranus will be 0.4 degrees north of the
moon, with an occultation visible over most of Australia, and part of New
Guinea.

The phases of the moon for September are as follows:
Thurs. Sept.  7  full moon (largest of 2006)
Thurs. Sept. 14  last quarter
Fri.   Sept. 22  new moon
Sat.   Sept. 30  first quarter
A wonderful monthly moon calendar can be printed off from
http://stardate.org/nightsky/moon.  For the NASA kids' calendar for the
month, go to http://spaceplace.nasa.gov/en/kids/calendar.shtml

Note that there is a partial lunar eclipse on September 7th - visible from
Africa, Asia, Australia and Eastern Europe.  An annular solar eclipse
happens on September 22nd, but is visible (even in partial phases) from only
South America, the eastern Caribbean, western Africa, and Antarctica.

One of the simplest sky charts can be found on the website 'Heavens Above',
at http://www.heavens-above.com.  Ignore the 'Register' bit.  Just 'Select'
your country, then your city, and then scroll down the page to 'Whole Sky
Chart'.  Type in what day you want, and pick a time of night.  Pick black on
white, as it's easier to read.  The maps show the constellations and the
positions of all the visible planets.  'Heavens Above' also tells you when
to watch for satellites, and the International Space Station (ISS)
passing over your home or observing site.  Check it out!

4.  Upcoming Meetings...

September 14-17, 2006, Roden, The Netherlands...
The IMC, the International Meteor Conference of the IMO, the International
Meteor Organization, will be held near Roden in the Netherlands.  This is
the annual get-together for both amateur meteor observers and professional
researchers alike.  Talks will cover all types of meteor observing - visual,
telescopic, photographic, video, and radio.  The total fee is 130
Euros, and includes the conference, all meals, all accommodation, an
excursion, and a conference t-shirt.  Special workshops will be held on
meteor orbit determination and radio meteors from September 11th to 13th,
with a separate fee.  For more info, check out http://www.imo.net/imc2006

For information on upcoming astronomy meetings, see: 'International
Astronomy Meetings List' at http://cadcwww.hia.nrc.ca/meetings

5.  For more info...

NAMN email: namn at namnmeteors.org
NAMN website: http://www.namnmeteors.org

Mark Davis, meteors at comcast.net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network

Cathy Hall, chall at cyberus.ca
Ottawa, Ontario, Canada
Writer, NAMN Notes

Lew Gramer, dedalus at alum.mit.edu
Homestead, Florida, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'

Kevin Kilkenny, namnfireball at 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 at alum.mit.edu

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

September 2006 NAMN Notes
written by Cathy Hall & edited by Mark Davis
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