NAMN Notes: December 2002

by Mark Davis and Cathy Hall

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. Geminids - The Final Highlight of the Year...
2. Other December Showers...
3. Heads up for New Years...
4. Christmas Gift Ideas for Meteor Observers...
5. Upcoming Meetings...
6. For more info...
1. Geminids - The Final Highlight of the Year...

The Geminid meteor shower is the final highlight of our meteor year! The rates are good, the meteors are bright, and the nights are long. It's a great shower for all observers, and especially for new observers whohave joined us since Leonid time. The International Meteor Organization (IMO) refers to the Geminids as 'one of the finest annual showers presently observable'.

The Geminids (GEM) reach a maximum on December 14th, probably about 10h UT, according to comments in the 2002 IMO Meteor Shower Calendar. For eastern North American observers, this means 5 a.m. EST. Hence the best 'night' to watch is the evening of the 13th and the morning of the 14th. The shower lasts from about December 7th to 17th. According to the IMO, 'well north of the equator, the Geminid radiant rises around sunset, and is at a usable elevation from the local evening hours onwards. In the southern hemisphere, the radiant appears only around local midnight or so'. For those interested in trying observations of this shower telescopically, the fainter meteors should peak about a day before the regular peak. For those who (heaven forbid) might be clouded out on the 13/14th, good meteor rates can also be seen before and after that night.

The Zenithal Hourly Rate (ZHR) for the Geminids is about 120 meteors per hour with the unaided eye. This is the number of meteors that an observer would expect to see if they were 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. Geminid meteors tend to be fairly bright, with many about the magnitude of the stars in the Big Dipper - and many leave trains behind them. They are very impressive meteors, and a delight to observe, in spite of the winter cold for many observers.

The radiant for the Geminid meteors at maximum is at 112 degrees, ie. RA 07h 28.2m, Dec +33, which is close to the bright star Castor in the constellation of Gemini the Twins. These meteors are of medium velocity at about 35 km per second. For a map showing the movement of the radiant over time, check out http://www.imo.net/calendar/cal02.html#Geminids

The parent body of the Geminids is the asteroid 3200 Phaethon. This was announced by the International Astronomical Union (IAU) in 1983, and was the first time that an asteroid, as opposed to a comet, had been linked to a meteor shower. Some investigators say that Phaethon is the largest remnant of the parent of the Geminid stream, and that it is still unclear as to what the true 'parent' is.

Reports of the Geminid shower go back only to the 19th century, although it is believed that activity goes back much further. The IMO states that 'the first indications of the Geminid meteor shower were published by the early Belgian meteor researcher Quetelet (1841, 1861), who mentioned high meteor activity on 1830 December 12-13 at Heiligenstadt (Germany), from where 40 fireballs were reported'.

December's Geminids are the last major shower of the year - so bundle up and get out to observe!

2. Other December Showers...

There are a number of lesser showers visible in December as well. To help you in seeing where all these will come from, print off a set of our NAMN star charts from http://www.namnmeteors.org/charts.html and use them to mark the various shower radiants on.

The chi Orionids (XOR) reach a weak maximum about December 2nd, with a radiant at 082 degrees, ie. RA 05h 28.2m, Dec +23, which is about 5 degrees south of Beta Tauri. They can be seen until about December 15th. ZHR rates are low, only about 3 meteors per hour at maximum. They are slow, with a velocity of about 28 km per second. The chi Orionids are considered to be possibly a continuation of the ecliptic activity after the Taurids are no longer active. This shower has occasional fireballs. A map showing the movement of the radiant up to December 15th can be found at http://www.imo.net/calendar/cal02.html#chi-Orionids

The Phoenicids (PHO) reach a maximum on December 6th at 14.20 UT, ie. 9.20 a.m. EST on the morning of the 6th. The radiant is at 018 degrees, ie. RA 1h 12m, Dec -53, which is roughly 35 degrees down to the left of beta Cetus - so this is a shower for more southerly observers. A map showing the radiant position can be found at: http://www.imo.net/calendar/cal02.html#Phoenicids. These meteors can be seen until about December 9th. ZHR rates are variable, usually only about 3 meteors per hour or less - but they did reach about 100 meteors per hour back in 1956. These are very slow meteors, with a velocity of about 18 km per second.

Also for southern observers, the Puppid-Velids (PUP) reach a maximum about December 7th, with a radiant at 123 degrees, ie. RA 08h 12m, Dec -45,which is about 17 degrees down to the left of the star eta Canis Major. The IMO states that 'the activity is so badly-known, we can only be reasonably sure that the highest rates occur in early to mid December... most Puppid-Velid meteors are quite faint, but occasional bright fireballs, notably around the suggested maximum here, have been reported'. These are average velocity meteors, at about 40 km per second, with a ZHR rate of about 10 meteors per hour. They can be seen until about the

15th.

The Monocerotids (MON) reach a maximum about December 9th, with a radiant at 100 degrees, ie. RA 06h 40.2m, Dec +08, which is just south of the left foot of Gemini. These meteors are visible until about December 17th. ZHR rates at maximum are low, about 3 meteors per hour. Monocerotids are average velocity, at about 42 km per second. Apparently telescopic results suggest a later maximum, around December 16th. Observations are encouraged. A map of the radiant is at http://www.imo.net/calendar/cal02.html#Geminids.

According to recent studies, this shower could be the source of many of the spectacular fireballs of the eleventh century. Many of these are documented in the writings of Ma Touan-lin, a historian of the pre-Mongolian era, who collected observations of over 1,500 fireballs going back over 24 centuries!

The sigma Hydrids (HYD) reach a maximum on December 12th, with a radiant at 127 degrees, ie. RA 08h 28.2m, Dec +02, off to the left of Procyon in Canis Minor, south of the little circlet of stars at the top of Hydra. They can be seen from about December 3rd to 15th. These are fast meteors, with a velocity of about 58 km per second. ZHR rates are about 2 meteors per hour. Plotting is encouraged - as the maximum may occur up to 6 days earlier than thought. A map showing the radiant movement can be found at http://www.imo.net/calendar/cal02.html#sigma-Hydrids.

The Coma Berenicids (COM) have a maximum on December 20th, with a radiant at 175 degrees, ie. RA 11h 40.2m, Dec +25, which is about 10 degrees north of the bright star Denebola in the triangle of Leo. They can be seen from about December 12th until January 23rd. ZHR rates at maximum are about 5 meteors per hour. These are fast meteors, with a velocity of about 65 km per second. This shower is quite possibly associated with Comet Lowe, 1913 I, discovered by an amateur astronomer in south Australia.

Lastly, the Ursids (URS) reach a maximum on December 22nd, with a radiant at 217 degrees, ie. RA 14h 28.2m, Dec +76, which is just above the pointer stars of Ursa Minor, the Little Dipper. They can be seen from about December 17th to 26th. ZHR rates at maximum are about 10 meteors per hour - quite respectable. On occasion, this shower has surged up to about 50 meteors per hour, so is worth monitoring! The Ursids are medium velocity, at about 33 km per second, and tend to be faint. The Ursids bear an association with Comet Mechain, now called Comet Tuttle. Pierre Mechain of France discovered the comet on January 9, 1790, but there

were not enough observations of it to discover its periodic nature. It was recovered on January 5, 1858 by Horace Tuttle of Massachusetts, and given his name instead.

For information on other minor showers visible, check out Gary Kronk's 'Comets and Meteor Showers' website at http://comets.amsmeteors.org

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

This month, the phases of the moon are as follows:
Wed. Dec. 4 new moon
Wed. Dec. 11 first quarter
Thurs. Dec. 19 full moon
Fri. Dec. 27 last quarter
Planets at midmonth are:
Venus -4.6 low in east in morning
Jupiter -2.4 in Leo
Mercury -0.6 low in southwest in evening
Saturn -0.5 in Taurus
Mars 1.7 in Virgo/Libra in morning sky

A star map showing the planets' positions can be printed off from http://www.heavens-above.com - Select your location, then go to 'Whole Sky Chart'. On December 6th, Venus and Mars will be very close together. On December 30th, Venus, Mars and the moon will be close, with an occultation of Mars in NE Asia except NE Siberia, and in Japan except for the southern tip.

For recording sheets for your meteors, go to http://www.namnmeteors.org/namn_form.html and for an email template to use in typing out your observations: http://www.namnmeteors.org/appendixC.html

For charts to use in estimating your limiting magnitude, go to http://www.imo.net/visual/major01.html#table2

For information on what to record for visual observing, check out our NAMN Observing Guide at: http://www.namnmeteors.org/guide.html

And - if you have any questions on observing, drop a note to our NAMN Coordinator at meteors@comcast.net

3. Heads Up for New Years...

The 2003 IMO Meteor Shower Calendar is now available online at http://www.imo.net/calendar/cal03.html. You might want to print a copy off and put it in a binder for details on meteor showers throughout theyear.

Of special note at this busy time of year - and often forgotten over the holidays - is the Quadrantid meteor shower.

The Quadrantids (QUA) start to become active on New Years, January 1st, and run until the 5th. The maximum is on January 4th at about 0h UT, which is 7 p.m. EST on January 3rd for eastern North American observers. The IMO, in their introduction to the 2003 Calendar, states that this year 'sees two of the 'big three' major showers - the Perseids and Geminids - lost to bright moonlight, but the third, the Quadrantids, are well-placed'.

ZHR rates for the Quads are variable. They are usually stated as being about 120 meteors per hour, but can vary between 60 and 200 per hour. These are average velocity meteors, at about 41 km per second. The radiant is at 230 degrees, ie. RA 15h 19.8m, Dec +49, which is in northern Bootes. A Map showing the radiant can be found at http://www.imo.net/calendar/cal03.html#Quadrantids

The time of maximum activity is usually very brief, only several hours, so is very weather-dependent. However, as the fainter (telescopic) meteors may reach a maximum up to 14 hours prior to the regular max, and the radio meteors up to 9-12 hours after the regular max, all observations between January 1st and 5th will be very valuable!

4. Christmas Gift Ideas for Meteor Observers...

Looking for Christmas gift ideas for meteor observers? Consider the following...

Membership in the International Meteor Organization (IMO): Includes a great bimonthly publication, very readable for the serious amateur. Send check or money order to Mr. Robert Lunsford, IMO Secretary-General, 161 Vance Street, Chula Vista, CA 91910, U.S.A. with The check or money order payable to "Mr. Robert Lunsford". Cost: $20 US for regular membership, with newsletter by surface mail. For more information, check out http://www.imo.net And - donations to the IMO to help support meteor activities around the globe are also always welcome!

Books on meteors, meteorites, comets, and impacts:
... Meteors, by Neil Bone
... The Heavens on Fire - The Great Leonid Meteor Storms, by Mark
Littmann
... Rocks from Space, by O. Richard Norton
... Meteorites: Their Impact on Science and History,
ed. by Brigitte Zanda and Monica Rotaru
... The Cambridge Encyclopedia of Meteorites, by O. Richard Norton
... Comet Science - The Study of Remnants from the Birth of the Solar
System, by Jacques Crovisier and Therese Encrenaz
... Rendezvous in Space - The Science of Comets,
by John C. Brandt and Robert D. Chapman
... Rogue Asteroids and Doomsday Comets, by Duncan Steel
... Target Earth, by Duncan Steel
... T.rex and the Crater of Doom, by Walter Alvarez
Books for kids:
... Let's Investigate Magical, Mysterious Meteorites,
by Madelyn Wood Carlisle
... Asteroids - Invaders from Space, by Robert Kraske
Accessories for meteor observing:
... talking clock or watch, available at institutes for the blind
... pocket tape recorder for recording meteors
... pocket radio to keep you company while observing solo
... nice warm winter clothes for observing!
5. Upcoming Meetings...

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

6. For more info...
NAMN email: namn@atmob.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
Metcalfe, Ontario, Canada
Co-author, NAMN Notes
Lew Gramer, dedalus@alum.mit.edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'
Kevin Kilkenny, namnmeteorites@yahoo.com
(new address)
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