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. 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...
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, 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@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@cox.net
To read up further on telescopic, photographic and video recording of meteors, check out the IMO website at http://www.imo.net
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@milkyway.gsfc.nasa.gov.)
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 twilightFor 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 quarterA wonderful monthly moon calendar can be printed off from http://stardate.org/nightsky/moon. For the NASA kids' calendar for August, 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 ISS, the International Space Station, passing over your home or observing site. Check it out!
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
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
Back issues of NAMN Notes can be found on-line 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 or
to find out information on our weekly chat sessions:
Contact Lew Gramer at:
dedalus@alum.mit.edu