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(meteorobs) NAMN Notes: April 2003

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NAMN Notes:  April 2003
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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 Brings the Lyrids...
2.  Other April Meteor Showers...
3.  Upcoming Meetings...
4.  For more info...


1.  Spring Brings the Lyrids...

The Lyrid meteor shower (LYR) is the highlight of our spring meteor season!
After months of cold temperatures, spring is finally on its way, with a very
nice shower for both seasoned observers and novices alike.

The Lyrid shower is the oldest meteor shower for which observations have
been found.  It was seen in ancient China over 2,000 years ago.  According
to the IMO Handbook, of the International Meteor Organization, the Lyrid
meteoroid stream - the actual debris shed by its parent comet - is highly
inclined in its orbit.  This means that its path doesn't come near our solar
system's planets, and hence is not disrupted by those planets' gravity.
Because of this, although the stream is very old, it acts younger than its
age.  It has a short period of maximum activity, usually only hours long,
and has higher density concentrations of material - clumps of debris - which
can cause interesting outbursts of activity.

Do all meteor showers have comets as parents?  No, but the Lyrids do.  They
are debris from Comet Thatcher, C/1861 G1.  This comet 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.  That means it was slightly fainter
than the stars in the Big Dipper with a tail about 1/5 the distance between
the pointer stars of the Dipper.  It was determined that the orbit of the
comet was elliptical, and that the comet returns to our area of the solar
system about every 415 years.

The Lyrids reach a maximum on April 22nd at 22h00m UT, but can be seen from
about April 16th to 25th.  These are average velocity meteors at about 49
km per second.  ZHR rates on the 22nd will reach probably about 18 meteors
per hour - but the rates are variable.  ZHR, Zenithal Hourly Rate, is the
number of meteors, on average, that an observer would see from a dark
country sky if the radiant, the area in the sky where the meteors seem to
come from, is directly overhead.  Occasional outbursts of activity have
occurred - up to about 90 meteors per hour.  It has recently been found that
the length of the peak time is variable - and that there is sometimes
a short-lived increase in the number of fainter meteors during that peak
period.  Note that the 22h UT peak of the Lyrids refers to Universal Time in
Greenwich, England.  For east coast North American observers, 22h UT means 6
pm EDT.

Where is the radiant for the Lyrids?  It's in the constellation of Lyra, the
Lyre.  In ancient mythology, the lyre was the musical instrument of Orpheus.
Orpheus was a son of Apollo, a god of prophecy.  His mother was Calliope,
the muse of epic poetry.  Orpheus was a gifted minstrel - it was he who
saved Jason and the Argonauts in their quest for the Golden Fleece by
drowning out the sounds of the Sirens with his playing.  Orpheus married
Eurydice, a nymph, who was unfortunately bitten by a snake and died.
Orpheus was extremely upset, and took a trip to the underworld to somehow
get her back by charming everyone with his playing.  The rulers of the
underworld, Hades and Persephone, agreed on the condition that once back on
earth, Eurydice always follow behind Orpheus, and he not turn around to look
at her.  When he failed in this and turned to look at his wife, Eurydice
was zapped back to the underworld, and poor Orpheus was left all alone.

Orpheus wandered around for many months playing his musical lyre.  He
met his end when he refused the advances of a band of drunken female
followers of Dionysus and the women tore him limb from limb taking his
head to the island of Lesbos.  His body - the rest of it - was buried in
Thrace, where supposedly nightingales now sing sweetly.  The god Apollo
gathered up the musical lyre of Orpheus and placed it in the heavens...

On the date of maximum, April 22nd, the radiant of the Lyrid meteor shower
will be at 271 degrees, i.e. 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 movement of the radiant can be found on the IMO website at
http://www.imodot net/calendar/cal01.html#Lyrids.  Meteor radiants do move a
bit from night to night.

The Lyrids are a great meteor shower for both beginners and seasoned
observers.  The nights are much warmer now, and observing for long periods
of time is quite enjoyable.  If you are new to meteor observing, take out a
lawnchair and sleeping bag and see what it's all about.  If you want to try
recording some meteor data - and help out the meteor researchers and
scientists around the globe - then check out our NAMN Observing Guide at
http://www.namnmeteors.org/guide.html


2.  Other April Meteor Showers...

The Virginids (VIR) can be seen until mid-April.  They are known as the
ecliptic activity as the radiant moves along the path of the ecliptic in the
sky.  These are slow to average velocity at about 30 km per second.  ZHR
rates are about 5 meteors per hour.  Radiant coordinates are as follows:
April  10   203  -7  i.e.  RA 13h 31.8m  Dec -7
April  15   205  -8  i.e.  RA 13h 40.2m  Dec -8

For easy reference, print yourself off a set of our NAMN star charts at
http://www.namnmeteors.org/charts.html  Using these charts, it is easy to
read off where the various meteor radiants are.  Various standard stars
are marked with numbers for their brightness - so these maps are also very
handy for judging the brightness of the meteors you see.

The pi Puppids (PPU) reach a maximum on April 24th at 3h UT.  This means 11
pm EDT on April 23rd for observers in eastern North America.
Pi Puppids can be seen from about April 15th to 28th.  These are
nice slow meteors with a velocity of about 18 km per second.  At maximum,
the radiant is at 110 degrees, i.e. 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.  The ZHR rate for this shower is variable and has reached
as high as 40 meteors per hour on occasion.  A map showing the movement of
the radiant can be found at
http://www.imodot net/calendar/cal01.html#pi-Puppids.  The pi Puppids are
debris from Comet 26P/Grigg-Skjellerup, discovered in 1902 by John Grigg of
Thames, New Zealand, and J.F. Skjellerup of Cape of Good Hope, South Africa.
According to the IMO, "this is a young stream... and shower activity has
only been detected from it since 1972... Comet Grigg-Skjellerup reached
perihelion last in October 2002, so this will be an interesting year to
check for whatever happens".

The eta Aquarids (ETA) start to become active about April 19th although
won't reach a maximum until May 6th.  A map showing the radiant position
over the weeks can be found at
http://www.imodot net/calendar/cal03.html#eta-Aquarids.  These are fast
meteors at about 66 km per second.  At maximum in early May, the ZHR rate
will be about 60 meteors per hour but rates in April will be low.  The eta
Aquarids are debris from Halley's Comet.

The Sagittarids (SAG) start to become active about April 15th and can be
seen through until about mid-July.  These are average velocity meteors at
about 30 km per second.  ZHR rates are about 5 meteors per hour.  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.  Radiant coordinates for the
month are as follows:
April 15  224  -17  i.e.  RA  14h 55.8m  Dec -17
April 20  227  -18  i.e.  RA  15h  7.8m  Dec -18
April 25  230  -19  i.e.  RA  15h 19.8m  Dec -19
April 30  233  -19  i.e.  RA  15h 31.8m  Dec -19

For information on 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 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.

This month, the phases of the moon are as follows:
Tues. April  1  new moon
Wed.  April  9  first quarter
Wed.  April 16  full moon (largest of 2003)
Wed.  April 23  last quarter

Planets at midmonth, and their magnitudes, are:
Mercury  -0.6  in west in evening
Venus    -4.0  in east in morning
Jupiter  -2.3  in Cancer
Saturn    0.1  in Taurus
Mars      0.3  in Sagittarius, then Capricornus
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'.

Recording sheets for your data can be found at
http://www.namnmeteors.org/namn_form.html
and an email template at
http://www.namnmeteors.org/appendixC.html
with information on what to record found in our NAMN Observing Guide at
http://www.namnmeteors.org/guide.html


3. Upcoming Meetings...

May 10, Milton Keynes, UK...
The Pro-am Meeting on Comets, Meteors & Meteorites will be held at the Open
University in Milton Keynes, UK.  This is a discussion group for all
astronomers, sponsored by the British Astronomical Association and the Royal
Astronomical Society.  Brian Marsden will give the George Alcock Memorial
Lecture.  Speakers include Neil Bone of the BAA.  Details can be found at
http://www.astdot cam.acdot uk/~jds/proam.htm   For information, contact
Jonathan Shanklin at comet@britastro.com

June 25 - July 2, Moscow, Russia...
The 95th Anniversary of the Tunguska Event, the Tunguska 2003 International
Conference, will be held over several locations - Krasnoyarsk, Vanavara,
and Moscow, with talks and a special excursion to the epicenter of the
Tunguska event.  The organizers welcome all those interested in the
Tunguska event - even if you just want to come as a tourist to visit the
famous Tunguska site!  For information, check out
http://olkhov.narod.ru/conf03.htm#7b or contact Elena Batygina at
batyginaek@evenkya.ru.

August 10-14, Washington State, USA...
The Cometary Dust in Astrophysics conference will be held at Crystal
Mountain, in Washington State, USA.  The purpose of the meeting will be the
integration of astrophysical observations of comets and cosmic dust with
laboratory analyses of interplanetary dust, stardust, and meteorites.  For
more information, check out http://stardust.wustldot edu/CDA.html  or contact
Donald Brownlee at brownlee@bluemoon.astro.washingtondot edu

September 18-21, Bollmannsruh, Germany...
The IMC, International Meteor Conference, of the IMO, the International
Meteor Organization, will be held in Bollmannsruh, Germany.  This is the
annual world meeting for amateur meteor observers and professionals alike!
The location of the conference is a hostel near the town of Brandenburg,
about 40 km west of Berlin.  It is situated in a rural area by a lake, and
facilities include accommodation in bungalows, a cafe and bar, a lecture
hall, an open air stage, and a place for a campfire and barbecue.  The
special  excursion during the conference will be to Berlin to the Museum for
Natural History for a lecture on meteorites and viewing of the meteorite
collection.  For more information, check out
http://aipsoe.aipdot de/~rend/2003imc.html and http://www.imodot net/news/imc.html
or contact Ina Rendtel at IRendtel@t-onlinedot de.  IMC 2003 marks the 15th
anniversary of the IMO - so meteor observers from around the globe are all
invited for this special event!

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


4.  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
Co-author, 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 or to find out information on our
weekly chat sessions:
Contact Lew Gramer at: dedalus@alum.mitdot edu

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

April 2003 NAMN Notes co-written
by Mark Davis and Cathy Hall
==============================================

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