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NAMN Notes: September 2005
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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

1. Autumn's Aurigid Meteor Showers...
2. More on Aries-Triangulid & September Taurid Meteors - by G.W. Gliba...
3. Other September Showers...
4. Upcoming Meetings...
5. For more info...

Welcome to autumn, and the coming of the Aurigids! We have two meteor showers from Auriga in September, and both of these have peaks that are close to the darker skies of the new moon period.

The alpha Aurigids (AUR) started to become active about August 25th, and reach a peak on September 1st at 0h Universal Time (UT). These are fast meteors at about 66 km per second. ZHR rates on the 1st will reach about 7 meteors per hour. A map of the radiant can be found on the website of the International Meteor Organization (IMO) at http://www.imo.net/calendar/2005/summer#alpha-aurigids

What is ZHR? This is Zenithal Hourly Rate, and is the number of meteors, on average, that an observer would expect to see in an hour if the radiant, or the area in the sky where the meteors seem to come from, is directly overhead - and if an observer is out under dark country skies.

Monitoring this shower may yield some surprises. The alpha Aurigids had short unexpected bursts of about 30-40 meteors per hour in 1935, 1986 and 1994. All observations are encouraged - and not just on the peak night. The shower lasts until about September 8th, and all observations are very valuable.

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

However, the International Meteor Organization splits out this activity into 2 parts in a more detailed description in their 2005 Meteor Shower Calendar at http://www.imo.net/calendar/2005/summer#delta-aurigids

"Both these essentially northern hemisphere showers... appear to be part of a series of poorly observed showers with radiants in Aries, Perseus, Cassiopeia and Auriga, active from late August into October... 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 parameters listed above <ie. September 9th>... primarily derive from the "September Perseid" phase. The "delta-Aurigid" phase seems to give a weak maximum around... September 23-24... ZHR ~ 3"

If you want to record data on these showers 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@comcast.net

NAMN has some good star charts to mark your radiants on before you go out observing. These charts also show constellations for the whole sky, and give the brightness of a number of stars to use in judging the magnitude of the meteors you see. Our 4 printable charts can be found at http://www.namnmeteors.org/charts.html. Set your printer to 'landscape' mode.

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

The maximum for the Aries-Triangulid (ie. alpha Triangulid) minor meteor shower should be on September 12th or 13th. There is some historical evidence that this stream may be periodic, and/or have several submaxima. More observations are still 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 most active around September 10th to 14th. There is some evidence, from Italian meteor observers, that the Aries radiant may be most active in late August and early September.

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 in 1934, 1940, 1951, 1993, 1998, and possibly 1999. Last year, 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. Significant activity means seeing four or more meteors per hour from a radiant this time of the year, because sporadic meteor pollution causes chance alignments to false, or low level radiants.

It is probable that some activity will be seen this year. The moon will be just past first quarter, so will set when the radiant starts to get to a good elevation above the eastern horizon. Some activity has been reported every year since this meteor stream was first discovered to be possibly annual, twelve years ago. Gary Kronk mentions the history of this minor meteor shower on his 'Comets and Meteor Showers' website at http://comets.amsmeteors.org

The September 2004 Sky & Telescope magazine had an article on the September Taurid shower, which is another 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. In 1993, WGN (originally Werkgroupniews), the Journal of the IMO, 31:3 (2003), an article on the existence of this putative 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, some modest activity was reported for the September Taurids by a few experienced seasoned meteor observers last year, who took account of the apex source meteors. So, it may still be a real minor meteor shower, albeit barely detectable above the sporadic background. The radiant for the September Taurids is located just between the Hyades and Pleiades star clusters. The jury is still out on this shower. Stephen O'Meara should be given credit for bringing this almost forgotten possible minor meteor shower to light.

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.

(Thanks to George Gliba for providing details on these showers. Questions can be directed to him at gliba@milkyway.gsfc.nasa.gov)

The Piscids (SPI) reach a peak on September 19th 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/2004/summer

The Sextantids, a daytime meteor shower normally detected by radio observers, could yield some visual meteors. The peak is expected on September 27th at 9h Universal Time, but may occur a day earlier. The radiant is at 152 degrees, ie. RA 10h 7.8m, Dec +0, as per the IMO 'Working List of Daytime Meteor Streams' at http://www.imo.net/calendar/2005/remarks

For other minor showers not on the International Meteor Organization, 'Working List of Visual Meteor Showers', check out the very informative website 'Comets and Meteor Showers' by Gary Kronk at http://comets.amsmeteors.org. It gives further details on more obscure showers, and a wealth of observational and historical detail on all the major and minor showers.

Besides September's main activity and other minor showers, there is also sporadic meteor activity, as commented on by George Gliba in his article on the Aries-Triangulid and September Taurid 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        -3.9  very low in west-southwest in evening twilight
Jupiter      -1.7  in Virgo, very low in west-southwest in evening twilight
Mars         -1.2  in Aries
Saturn        0.3  in Cancer, in east in morning sky

The phases of the moon for September are as follows:

Sat. Sept.  3   new moon
Sun. Sept. 11  first quarter
Sun. Sept. 18  full moon (the 'Harvest Moon')
Sun. Sept. 25  last quarter

September 10-14, 2005, Belgium...
'Radio Meteor School 2005' will be held in Oostmalle, Belgium. This will be a five day tutorial on the physical and mathematical theory of radio meteor observations given by Dr. Oleg Belkovich of Russia. This workshop is for serious radio meteor observers. The cost for the workshop is about 150 Euros. For more information, check out the IMO website at http://www.imo.net/imc2005/radioschool.php and contact the organizers at imc2005@imo.net

September 15-18, 2005, Belgium...
The 2005 IMC, International Meteor Conference of the International Meteor Organization, will be held in Oostmalle, Belgium. Oostmalle is about 70 km north of Brussels and about 30 km northeast of Antwerp. The conference is being organized by Urania, the public observatory of Antwerp. Accommodation will be at the Provinciaal Vormingscentrum Malle, with an excursion to the city of Lier. This is a great opportunity to meet and chat with meteor observers from all around the globe - so mark it on your calendar now and plan to attend! The participation fee for those now registering is 130 EUR, and includes all accommodation, meals and the conference registration. Financial assistance is available in some cases. There will be a guest lecture by Prof. Dr. Philippe Claeys on meteorite impacts. For information on the conference, check out http://www.imo.net/imc2005. For questions, contact Jan Verbert at imc2005@imo.net

September 26-30, 2005, Hawaii...
The 2005 'Dust in Planetary Systems' conference will be held in Lihue, Hawaii. It is only held about every 5 years, and this year is a 5-day series of talks. Speakers include Jack Baggaley on 'Interstellar Meteors', Margaret Campbell-Brown on 'The Meteoroid Environment: Shower and Sporadic Meteors', Peter Brown on 'Interstellar Meteoroids Detected by the Canadian Meteor Orbit Radar', and Peter Jenniskens on 'Meteor Showers from Broken Comets'. Check out the abstracts and the registration info on the website at http://www.lpi.usra.edu/meetings/dust2005. For more information, contact Eberhard Gruen of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany at eberhard.gruen@mpi-hd.mpg.de

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

NAMN email: namn@namnmeteors.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
Ottawa, Ontario, Canada
Writer, NAMN Notes

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

Kevin Kilkenny, namnfireball@earthlink.net
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites

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http://www.meteorobs.org
by selecting 'Browse Archive by Month'

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Contact Lew Gramer at:
dedalus@alum.mit.edu