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(meteorobs) NAMN Notes: April 2004

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NAMN Notes:  April 2004
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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.  Spring Lyrids Bring Surprises?...
2.  Other April Showers...
3.  International Astronomy Day...
4.  Upcoming Meetings...
5.  For more info...


1. Spring Lyrids Bring Surprises?...

For meteor observers, spring brings the Lyrids!  This debris from Comet
Thatcher encounters the earth starting about April 16th and continues
until about the 25th.  Note that the peak of the Lyrids (LYR) this year is
on April 22 at 04h 10m UT, according to the International Meteor
Organization (IMO) in their detailed write-up from their 2004 Meteor Shower
Calendar.  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.

At maximum, the radiant for the Lyrids, the area in the sky where the
meteors seem to come from, is at 271 degrees, ie RA 18h 4.2m, Dec +34,
which is approximately halfway between the bright star Vega in Lyra and the
star mu Herculis.  A map showing the position of the radiant can be found
at

http://www.imodot net/calendar/cal04.html#Lyrids

These are average velocity meteors, at about 49 km per second.  The ZHR,
Zenithal Hourly Rate, is about 18 meteors per hour.  ZHR refers to the
number of meteors, on average, that an observer would expect to see if they
are out under a dark country sky, and if the radiant of the shower is
directly overhead at the zenith.

However - the Lyrid meteor shower can produce surprises!  The International
Meteor Organization gives more details in their 2004 Calendar:

"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 between sol = 32.0 degrees to 32.45 degrees (equivalent to 2004
April 21, 20h 20m UT to April 22, 7h 20m UT)...  Although the mean peak ZHR
was 18 over the thirteen years, actual peak ZHRs varied dependent on when
the
maximum time occurred...  (The last very high maximum 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... it varied from 14.8 h in 1993 to 61.7 h in 2000...  Best rates are
normally achieved for just a few hours however.  One other aspect... was
that occasionally, as their highest rates occurred, the Lyrids produced a
short-lived increase in fainter meteors."

The IMO sums it up when they say "overall, the unpredictability of the
shower in any given year always makes the Lyrids worth watching".  If you
have clear skies for the Lyrids this year, please try to help us out with
as many observations as possible during this period!


2.  Other April Showers...

The Virginid meteor activity (VIR) continues until about April 15th.  These
are almost slow meteors at about 30 km per second.  ZHR rates are about 5
meteors per hour.  Positions of the radiant in April 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

By mid-April on the 15th, the radiant will be about 5 degrees up to the
left of the bright star Spica in Virgo.  These meteors are known as the
ecliptic activity as the radiant moves along the path of the ecliptic in
the sky.  The origin of the Virginids, as far as parent bodies are
concerned, is undetermined.

A set of 4 star maps that you can use while observing - to mark radiants
on and with magnitudes of standard stars marked - can be printed off from
our website at

http://www.namnmeteors.org/charts.html

These maps show sky coordinates both in hours and minutes (like normal star
maps) and in the degree system (like the IMO coordinates given here for the
Virginids) - so it is easy to locate where the meteor radiants are!

The pi Puppids (PPU) reach a peak on April 23rd at 9h UT, with a radiant at
110 degrees, ie. RA 7h 19.8m, Dec -45, which is about 15 degrees due south
of the star eta Canis Majoris, the bottom left foot star of Canis Major.  A
map showing the position of the radiant, and its movement throughout April,
can be found at

http://www.imodot net/calendar/cal04.html#pi-Puppids

These meteors are debris from Comet 26P/Grigg-Skjellerup, and have been
seen since about 1972.  The comet was discovered in 1902 by John Grigg of
Thames, New Zealand and J.F. Skjellerup of Cape of Good Hope, South Africa.
The pi Puppids are slow meteors with a velocity of about 18 km per second.
ZHR rates are listed by the IMO as "periodic, up to around 40" meteors per
hour. They can be seen from about April 15th to the 28th.

The eta Aquarids (ETA), although not reaching a peak until May 5th, start
to become active about April 19th.  This shower is debris from Halley's
Comet. A common misconception is that Halley discovered this comet.  He
did not. However, his studies led to the realization that previous
sightings of it were all of the same comet - and this led to his name
becoming associated with the comet.  The eta Aquarids are fast meteors,
with a velocity of about 66 km per second.  ZHR rates at maximum will
be about 60 meteors per hour, but rates in April will be much lower.
Coordinates for the radiant during April are as follows:

Apr. 20  323 -7  ie. RA 21h 31.8m Dec -7
Apr. 25  328 -5  ie. RA 21h 52.2m Dec -5
Apr. 30  332 -4  ie. RA 22h 7.8m  Dec -4

On April 20th the radiant will be about 1 degree south of the star beta
Aquarius, the star called Sadalsuud.  A map showing the movement of the
radiant from about April 19th through to May 28th can be found at

http://www.imodot net/calendar/cal03.html#eta-Aquarids

The Sagittarids (SAG) start to become active about mid-April and will last
until about mid-July.  These are almost slow meteors with a velocity of
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 7.8m  Dec -18
Apr. 25  230 -19  ie. RA 15h 19.8m Dec -19
Apr. 30  233 -19  ie. RA 15h 31.8m Dec -19

On April 20th the radiant will be about 7 degrees north of the star
sigma Libra.  The Sagittarids are actually a complex of radiants near the
ecliptic and are surmised to be debris from a number of unknown bodies.
Fireballs have been associated with this meteor shower complex.

For observers interested in recording data on these showers for the meteor
researchers, take a look at our NAMN Observing Guide at

http://www.namnmeteors.org/guide.html

The information to record while observing includes such items as the time
the 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. Forms to
record your observations can be found at

http://www.namnmeteors.org/namn_form.html and

http://www.namnmeteors.org/appendixC.html

Questions on what to record, or how, can be sent to our NAMN Coordinator at
meteors@comcastdot net

Besides recognized main showers and other minor showers, there is also
sporadic meteor activity in April. 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. For information on minor showers, check out Gary
Kronk's 'Comets and Meteor Showers' website at

http://comets.amsmeteors.org

For observers interested in radio meteor showers, we have the April Piscids
with a peak on April 20th at 2h UT, and the delta Piscids with a peak on
April 24th at 2h UT.  For more information on observing meteors by radio,
check out the IMO website at

http://www.imodot net

To see where all the various planets are in your sky in the month of April,
go to

http://www.heavens-above.com

'Select' your location, then go to 'Whole Sky Chart'. To print off some sky
maps for various dates, change to 'black on white' first. If you have a
telescope, get out in April and enjoy some great planetary viewing. For
meteor observing, the planets are very good standards for estimating the
magnitude of the bright meteors you see!

Planets at midmonth, and their magnitudes, for northern observers, are:

Venus      -4.4  low in west in evening sky
Jupiter    -2.4  in Leo
Saturn      0.1  in Gemini
Mars        1.5  in Taurus, low in west in evening sky

This month, the phases of the moon are as follows:

Mon.  Apr.  5    full moon
Mon.  Apr. 12    last quarter
Mon.  Apr. 19    new moon
Tues. Apr. 27    first quarter

On Friday April 23rd, Venus will be about 1.5 degrees north of the moon,
and Mars about 2 degrees south of the moon.  For observers in the southern
hemisphere, the new moon of the 19th also brings a partial solar eclipse.

If you are new to meteor observing and still learning your constellations,
check out the website of the Hawaiian Astronomical Society for all kinds of
constellation maps - and background information on each constellation:

http://www.hawastsoc.org/deepsky


3.  International Astronomy Day...

What is Astronomy Day?  Quoting from the Sky and Telescope website at
http://skyandtelescope.com

"Doug Berger, former president of the Astronomical Association of Northern
California, founded this annual event in 1973 as a high-profile way of
drawing public attention to the science and the hobby through exhibits and
activities at urban centers...  Hundreds of astronomy clubs, observatories,
museums, colleges, and planetariums worldwide now host special
family-oriented Astronomy Day events and festivities."

This year International Astronomy Day is Saturday April 24th - and
Astronomy Week from April 19th to 25th.  Groups and individuals around the
globe will be using this opportunity to help spread the word about
astronomy - and about their particular interests in astronomy.  The
official Astronomy Day webpage is hosted by the Astronomical League, at

http://www.astroleague.org/al/astroday/astroday.html

Meteor observers can also help out - and help educate the public about
meteors!  Here are some suggestions:

- If your local astronomy club is doing a special event for the public, tag
along and help out... print off some NAMN handout material and take
it with you...  It is very rewarding to talk to the public about astronomy,
and answer all kinds of amazing questions!

- Offer to give a short talk on meteors or meteorites to a local school
class or a local scout group... kids love this stuff... take handout
material on meteors with you... and also print off some star charts for the
kids...

- Contact a local library or bookstore, and offer to help them set up a
special display for International Astronomy Day...

- If you are not available to help out in person... offer some handout
material on meteors to a group that is putting on a display for the
public...

What handout material is available for International Astronomy Day?

NAMN has the following handout sheets that we can email you to print off:

"How to Observe Shooting Stars"... a tri-fold, 2-sided brochure
"What are Meteors?"... a summary 1-page version of the brochure
"Surf the Astro Web!"... a list of recommended astro websites
"What's Up Tonight?"... what is visible in the sky on a given night
"What is a Meteor?"... a French info sheet, with many thanks to Pierre
Martin for the translation!

These resource sheets are available in electronic form at no charge - just
email either Cathy Hall at

chall@cyberusdot ca

or Lew Gramer at

dedalus@alum.mitdot edu

They are in Word format, and you can print off as many as you need.

Heavens-Above, the website that brings you information on satellites and
the times you can see the International Space Station go over your home,
also
has some great printable star maps at:

http://www.heavens-above.com

'Select' your location, then go down the page to 'Whole Sky Chart'.  Pick a
night and time, change to 'black on white', and print off a batch of star
charts to hand out to the public.

The International Dark Sky Association has great handout sheets on how to
use better lighting for your home... and preserve the Milky Way for your
kids!  A good one to print off for Astronomy Day is "Light Pollution: The
Problem, The Solutions" by D.L. Crawford at

http://www.darksky.org/infoshts/is134.html

International Astronomy Day is a great opportunity to help spread the word
about meteor observing - and how amateur astronomers can help out with real
science!  Get out, get involved - and have fun!


4. Upcoming Meetings...

June 4-6, 2004, Paris, France...
IWCA III, the Third International Workshop on Cometary Astronomy, will be
held at the Meudon and Paris Observatories in Paris, France.
The workshop announcement states that "its main objective is to promote
cometary observations among amateur astronomers and optimize the benefit of
these observations for the use by professional astronomers... it shall be
an opportunity for amateurs to meet professionals and exchange about their
techniques". Topics to be discussed include comet photometry, outgassing
rates, imaging with filters and spectroscopy, astrometry, observation of
trans-neptunians by amateurs, discovery and automatic sky surveys, space
missions to comets, and internet tools. Information can be found
at

http://www2.iap.fr/saf/IWCAIII

The contact for information is Nicholas Biver at nicolas.biver@obspm.fr

There is some financial support available for participants from eastern
Europe or other countries with limited financial resources. The workshop
has been timed to coincide with the transit of Venus on June 8th, visible
from France.

August 2-6, 2004, Rio de Janeiro, Brazil...
The 67th Annual Meeting of the Meteoritical Society will be held in Rio de
Janeiro, Brazil, and hosted by the Brazilian Center for Physics Research.
Topics covered will include various meteorite studies, carbonaceous and
other types of chondrites, martian meteorites, micrometeorites and IDP's,
impact processes and structures, asteroids and comets, and early solar
system chronology. Special sessions will cover current missions and future
sample returns, presolar grains, and South American impact structures. The
abstract deadline for electronic submissions is April 21st. Post-conference
tours will include the Araguainha Crater and other sites of interest.
Student travel grants are available. For more information, contact the
Conference Chair, Rosa B. Scorzelli at metsoc2004@cbpf.br and check out the
website at

http://www.lpi.usradot edu/meetings/metsoc2004/metsoc2004.2nd.html

August 16-21, 2004, London, Ontario, Canada...
Meteoroids 2004 will be held in eastern Canada, at the University of
Western Ontario in London. Experimental and observational methods discussed
will include optical observations of meteors including ground-based visual,
photographic, video, and telescopic techniques, satellite observations of
meteors in various passbands, measurements of meteoric atoms in the
atmosphere by lidars and other techniques, acoustic measurements using
infrasound and seismic detection techniques, radio detection of meteors
including VLF and ELF, meteor and large aperture radar observations, and
observations, in-situ satellite and laboratory measurements of dust and
meteorite material. Scientific areas discussed will include such topics as
dynamics of sporadic, shower and interstellar meteoroids, physics and
chemistry of meteoroids and their interaction processes in the atmosphere,
fireball and bolide phenomenology, mineralogy of extraterrestrial
materials, hypervelocity impacts on spacecraft, meteoroid models and flux,
and interrelation of meteoroids, meteorites, IDP's, asteroids and comets.
To receive further announcements directly on this, email

meteoroids2004@uwodot ca

The website for the conference is at http://www.uwodot ca/meteoroids2004

September 23-26, 2004, Varna, Bulgaria...
The IMC, the International Meteor Conference of the International Meteor
Organization, is being held this year in Varna, Bulgaria. This is the
worldwide meeting for meteor observers - both amateurs and professionals
alike. It is a great opportunity to meet observers from around the globe
and learn about research and projects being carried out. Details will
be posted on the IMO website at

http://www.imodot net

For more information on upcoming astronomy meetings, see: "International
Astronomy Meetings List" at

http://cadcwww.hia.nrcdot ca/meetings


5. For more info...

NAMN email: namn@atmob.org
NAMN website: http://www.namnmeteors.org

Mark Davis, meteors@comcastdot net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network

Cathy Hall, chall@cyberusdot ca
Metcalfe, Ontario, Canada
Writer, NAMN Notes

Lew Gramer, dedalus@alum.mitdot edu
Medford, Massachusetts, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'

Kevin Kilkenny, namnfireball@earthlinkdot 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@alum.mitdot edu

==============================================
Here's to 'Clear Skies' for April...

April 2004 NAMN Notes
written by Cathy Hall & edited by Mark Davis
==============================================


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