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. April - Lyrids for Spring!...
2. Other April Showers...
3. Comet Fragments Approaching Earth...
4. Upcoming Meetings...
5. For more info...
Welcome to spring! The highlight of the month of April is the Lyrid meteor shower.
The Lyrid shower is the oldest meteor shower for which observations have been found. It was seen in ancient China over 2000 years ago. The parent body of the Lyrids, Comet Thatcher, C/1861 G1, was discovered by A.E. Thatcher of New York on April 5th, 1861, and independently by Baeker of Nauen, Germany, with the unaided eye. It brightened to about magnitude 2.5 with a tail of about 1 degree in length. The orbit of Comet Thatcher is elliptical, and the comet returns to our area of the solar system about every 415 years.
The Lyrids (LYR) reach a peak on April 22nd this year, and can be seen from about April 16th to the 25th. The actual time of the peak has been found to be variable though, and may not necessarily coincide with the quoted 16h30m UT, Universal Time (ie. time at Greenwich, England). According to the International Meteor Organization (IMO):
"Audrius Dubietis and Rainer Arlt published a detailed investigation of the Lyrids in IMO results from 1988-2000 in 2001, the most detailed examination of the shower in modern times. Several fresh features were found, the most important of which was to redefine the maximum time as variable from year to year... equivalent to 2006 April 22, 8h40m - 19h00m UT."
How many meteors will we see? The ZHR rate for the Lyrid peak is quoted as about 18 meteors per hour.
What is ZHR? ZHR refers to Zenithal Hourly Rate, and is the number of meteors that an observer would expect to see in an hour, on average, if they are observing under a dark country sky, with no moon, and if the radiant, the area in the sky where the meteors seem to come from, is directly overhead at the zenith.
However, according to the IMO, the ZHR rate for the Lyrids has also been found to be variable:
"Although the mean peak ZHR was 18 over the thirteen years, the actual highest ZHRs varied dependent on when the maximum occurred. A peak at the ideal time produced the highest ZHRs...the last very high rates occurred outside the examined interval, in 1982 over the USA, when a short-lived ZHR of 90 was recorded... While generally thought of as having a short, quite sharp, maximum, this latest work revealed the shower's peak length was variable too... ZHRs were above half the maximum value... 14.8 hours in 1993 to 61.7 hours in 2000... occasionally, as their highest rates occurred, the Lyrids produced a short-lived increase of fainter meteors."
This is a shower that can hold surprises and is worth monitoring closely. The Lyrids are average velocity meteors at about 49 km per second, so are quite enjoyable for both beginning observers and more experienced observers alike. A map of the radiant can be found at http://www.imo.net/calendar/2006/spring
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
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 Virginids (VIR) started to become active about January 25th and last until about April 15th. These are almost slow meteors at about 30 km per second. ZHR rates are about 5 meteors per hour. Radiant positions are as follows:
Mar. 30 198 -5 ie. RA 13h 12m Dec -5 Apr. 10 203 -7 ie. RA 13h 31.8m Dec -7 Apr. 15 205 -8 ie. RA 13h 40.2m Dec -8
These positions are from the IMO 2006 Meteor Shower Calendar, available online at http://www.imo.net/calendar/2006
The pi Puppids (PPU) reach a peak on April 23rd at about 21h30m UT. They can be observed from about April 15th to 28th. This meteor shower is debris from Comet 26P/Grigg-Skjellerup, and activity has been detected since 1972. These are slow meteors, at about 18 km per second, so will be very distinctive. ZHR rates are variable, and reached as high as 40 meteors per hour for brief periods in 1977 and 1982. A map of the radiant can be found at http://www.imo.net/calendar/2006/spring. Although it is a more southerly radiant, all observers should monitor this shower for any surprises.
The eta Aquarids (ETA), although not reaching a maximum until May 6th, can be seen starting about April 19th. These are fast meteors, at about 66 km per second and are associated with Comet 1P/Halley. ZHR rates at maximum are expected to be between 50 and 60 meteors per hour in 2006 around the peak, but rates in April will be lower. A map showing the movement of the radiant throughout April and May can be found at http://www.imo.net/calendar/2005/spring
The Sagittarids (SAG) start to become active about April 15th and will last through until about July 15th. These are almost slow meteors at about 30 km per second. ZHR rates are about 5 meteors per hour. Coordinates for the radiant in April are as follows:
Apr. 15 224 -17 ie. RA 14h 55.8m Dec -17 Apr. 20 227 -18 ie. RA 15h 07.8m Dec -18 Apr. 25 230 -19 ie. RA 15h 19.8m Dec -19 Apr. 30 233 -19 ie. RA 15h 31.8m Dec -19
For other minor showers not on the International Meteor Organization’s '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 April'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 -4.1 low in east-southeast morning twilight (brilliant!) Jupiter -2.4 in Libra Saturn 0.2 in Cancer Mars 1.3 in Gemini
For a sky chart showing the positions of all the planets visible this month, go to http://www.heavens-above.com, select your country, then your city, and go to 'Whole Sky Chart'.
The phases of the moon for April are as follows:
Wed. Apr. 5 first quarter Thurs. Apr. 13 full moon Fri. Apr. 21 last quarter Thurs. Apr. 27 new moon
For a great printout of moon phases for the month, check out http://stardate.org/nightsky/moon
On March 24th, NASA posted a news release to its website at http://science.nasa.gov/headlines/y2006/24mar_73p.htm
Comet 73P/Schwassmann-Wachmann 3 has split into a number of fragments - and all of these fragments will fly past the earth from about May 12th to 14th. This will be an incredible event to witness, both for professional and amateur astronomers alike.
The comet was discovered on April 27, 1930 by A. Schwassmann and A.A. Wachmann of the Hamburg Observatory in Germany, on photographic plates exposed as part of a minor planet survey. It was diffuse, with a total magnitude of about 9.5 and a tail of about 3 arcminutes long. The comet's closest approach to earth came on June 1st, at which time it had brightened to about magnitude 6.5 and the tail reached a length of about 30 arcminutes. The comet broke apart in 1995, and now the pieces are undergoing further fragmentation.
Where and when do we look to see these fragments of Comet 73P/ Schwassmann-Wachmann 3 fly by?
Stay tuned to the following websites throughout April and May for the answers. Don't forget that we can observe these comet fragments now, even before they get close to the earth. Note that the fragments of 73P are called A, B, C, etc.
NASA Headlines:
http://science.nasa.gov
Sky and Telescope:
http://skyandtelescope.com
Kometarium by Burkhard Leitner - for finder charts ("karten"):
http://www.kometarium.com
Astrosite Groningen by Reinder Bouma and Edwin van Dijk - for finder charts:
http://www.shopplaza.nl/astro/
Skyhound by Greg Crinklaw - for more finder charts:
http://www.skyhound.com/sh/skyhound.html
The Harvard website - for actual coordinates:
(look under numbered periodic comets, then pick 73P/Schwassmann-Wachmann)
http://cfa-www.harvard.edu/cfa/ps/Ephemerides/Comets
As at the time of the NASA article, there were at least 8 comet fragments. There will be more fragments between now and the closest flyby dates.
And - there is speculation on a possible associated meteor shower. Its timing and strength will be dependent on what caused the breakup. For ongoing details on this possibility, we suggest you subscribe (if you haven't already) to our MeteorObs email list. Contact Lew Gramer at dedalus@alum.mit.edu for details. You can subscribe - and unsubscribe - from the list at any time.
This will be a really interesting event - get ready now!
I wonder if it's just a coincidence that this incredible comet flyby will occur at the very same time as the upcoming asteroids and comets conference in Europe. Just think. Vienna... Austria... Mozart... comet fragments traveling across the sky above the old historic observatories...
May 12-14, 2006, Vienna, Austria...
MACE 2006, the Meeting on Asteroids and Comets in Europe, will be held in
Vienna, Austria at the historic Kuffner Observatory. The scientific program
will be divided into 4 sessions - astrometry and celestial mechanics, the
physical study of asteroids and comets, instrumentation and techniques, and
workshops and hands-on practice. Excursions include visits to the Vienna
University Observatory, where Johann Palisa used the (then) largest
refractor in the world to discover asteroids, and to the famous meteorite
collection of the Natural History Museum, the largest of its kind in the
world. And - this is Mozart Year in Austria! For details, check out the
conference website at http://www.astrometrica.at/MACE
June 8-14, 2006, Ostersund, Sweden...
The Workshop on Impact Craters as Indicators for Planetary Environmental
Evolution and Astrobiology will be held in Ostersund, Sweden. Sessions
include terrestrial craters, craters on other planetary bodies, the
influences of the impact on the target area, the target area on the fate of
the projectile, and the properties of the impactor on the cratering process,
other consequences (eg. tsunamis), environments created by the impact and
their importance for life, and astrobiological aspects of impact cratering.
There will be two study field trips to the Lockne Crater, and an excursion
to the GeoCenter-Lockne Impact Crater Museum. For information, check out
the website at
http://www.geo.su.se/Lockne2006 and contact Dr. Jens Ormo of
the Planetary Geology Laboratory, CSIC/INTA, Madrid, Spain at ormo@inta.es
July 10-14, 2006, Singapore...
The AOGS, Asia Oceania Geosciences Society, will hold its 3rd Annual Meeting
in Singapore. Jeremie Vaubaillon has advised us that there will be a
special session on the field of meteor science. Topics covered at the
conference are quite varied - invited speakers include G. Consolmagno of the
Vatican Observatory on 'Evidence from Meteorites', Cheng Fang of Nanjing
University on 'Spectroscopic Approaches to Solar Flares: A Review', Paul
Jones of the Australia Telescope National Facility on 'Radio Observations
from Australia of Comet 9P/Tempel 1 for Deep Impact', and Dave Anderson of
NOAA on 'Solar Activity and Indian Monsoons'. The deadline for abstract
submission is February 15th. The deadline for reduced fees for registration
is May 15th. For information, check out the website at
http://www.asiaoceania-conference.org and contact
info@asiaoceania-conference.org
September 14-17, 2006, Roden, The Netherlands...
The IMC, the International Meteor Conference of 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 registration fee is 120
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. Mark Holland on your calendar for September! 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