(meteorobs) NAMN Notes: February 2007

Mark Davis meteors at comcast.net
Wed Feb 7 21:08:45 EST 2007


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NAMN Notes:  February 2007
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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.  Of Transient Phenomena and Comet McNaught...
2.  February Meteors for Winter Nights...
3.  Upcoming Meetings...
4.  For more info...


1.  Of Transient Phenomena and Comet McNaught...

These past weeks have been a wonderful time to consider transient phenomena.
Did you see Comet McNaught? If you weren't aware of this incredible comet
in our (briefly) northern and then southern skies, we will assume that you
were somehow temporarily lost on another world.

Congratulations go out to Robert McNaught for 'writing his name across the
sky', and letting us read his 'sky diary' day by day. We have been
following the photographs posted on many websites, notably at
http://www.spaceweather.com - and the photos have been exquisite.

We live in an age where we can see these images every day. Before digital
imaging, and photography, it took real time to be able to access the
drawings and images of comets. Sir Robert Ball wrote in his "The Story of
the Heavens", back in 1886:

"On the 22nd May, 1881, Mr. Tebbutt, of Windsor, in New South Wales,
discovered a comet which speedily developed into one of the most interesting
celestial objects seen by this generation. About the 22nd of June it became
visible from these latitudes in the northern sky at midnight. Gradually it
ascended higher and higher until it passed around the pole. The nucleus of
the comet was as bright as a star of the first magnitude...  This was the
first comet which was successfully photographed, and it may be remarked that
comets possess very little actinic power."

Times have changed.  Many of the images of Comet McNaught were taken with
digital equipment, gradually becoming more affordable to serious amateurs.
Images taken in real time, and images relayed to the populace in real time.
Much has been gained - but the old etchings and drawings in the historical
texts still keep us fascinated and spellbound.  They also provide our visual
historical comparisons to great comets of the past.

It is also in the old texts that we find some of the most apropos written
descriptions of comets.  Somehow, modern words and brief text messages just
don't cut it when trying to describe the beauty of comets - and Comet
McNaught.

Camille Flammarion wrote, in his "Astronomy for Women", back in 1903:

"Glittering, swift-footed heralds of immensity, these comets with golden
wings glide lightly through space, shedding a momentary illumination by
their presence.  Whence do they come?  Whither are they bound?"

"They arrive in every direction from the depths of space, as though to
reanimate themselves in the burning, luminous, electric solar centre...
Attracted by some potent charm toward this dazzling focus, they come
inquisitive and ardent, to warm themselves at its furnace...  Their motions
accelerate, they haste to plunge wholly into the radiant light.  At length
they burst out luminous and superb, when the day-star penetrates them with
his burning splendour, illuminates them with a marvellous radiance, and
crowns them with glory."

"These ethereal beauties whose blonde locks float carelessly upon the azure
night are not concerned with us; they seem to have no other preoccupation
than to race from sun to sun, visiting new heavens, indifferent to the
astonishment they produce in us.  They speed restlessly and tirelessly
through infinity; they are the Amazons of space."

"What suns, what worlds must they have visited since the moment of their
birth!  If these splendid fugitives could relate the story of their
wanderings, how gladly should we listen to the enchanting descriptions of
the various abodes they have journeyed to!"

Flammarion changed the title of his book for the English translation to
"Astronomy for Amateurs" - perhaps not to frighten off male readers with
descriptions of Amazon comets...

History remains important though.  Our studies of present comets would be
lacking without all that came before.  All the studies, all the drawings -
and even all the marvellous descriptions.

Here's to the 'Great Comet of 2007'... may it live in our history books...
and our memories.


2.  February Meteors for Winter Nights...

Flammarion wrote about meteors as well:

"Sometimes, when night has silently spread the immensity of her wings above
the weary earth, a shining speck is seen to detach itself in the shades of
evening from the starry vault, shooting lightly through the constellations
to lose itself in the infinitude of space."

"These bewitching sparks attract our eyes and chain our senses.  Fascinating
celestial fireflies, their dainty flames dart in every direction through
space, sowing the fine dust of their gilded wings upon the fields of heaven.
They are born to die; their life is only a breath; yet the impression which
they make upon the imagination of mortals is sometimes very profound..."

A bit flowery on the descriptive side... but the 'celestial fireflies' part
remains rather appropriate.

The alpha Centaurid (ACE) meteor shower peaks on February 8th this year at
about 11h Universal Time (UT), according to the International Meteor
Organization (IMO) - but activity can be seen through until about February
21st. These are fast meteors, with a velocity of about 56 km per second.
ZHR rates are variable.  Rates are usually about 5 meteors per hour, but
outbursts of 20 to 30 per hour have occurred.  Many of the alpha Centaurids
are very bright, even fireballs.  This is primarily a southern shower, with
a radiant located at about -59 degrees on a star map, about 50 degrees south
of the bright star Spica in Virgo.  A map of the radiant can be found on the
IMO website at http://www.imo.net/calendar/2005/winter

What is ZHR?  ZHR refers to Zenithal Hourly Rate, and is the number of
meteors that an observer would expect to see, on average, if they are
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.

Although not on the official International Meteor Organization
'Working List of Visual Meteor Showers', a watch should be kept for any
possible xi Bootids. These were first seen by observer George Gliba from
February 5/6 to 8/9 in 1997 from the Florida Keys. These were noted as
medium velocity meteors, with an average magnitude of about 3.6 and a
radiant near the star xi Bootes. Xi Bootis is about 8 degrees to the left
of the star Arcturus on a star map.

The delta Leonids (DLE) peak on February 25th, and can be seen from about
February 15th until March 10th. At maximum the radiant will be at 168
degrees, ie. RA 11h 12m, Dec +16, which is very near the star theta Leonis,
the lower right star in the triangle at the end of Leo. These are slow
meteors, with a velocity of about 23 km per second. ZHR rates at maximum
will be about 2 meteors per hour - but they will be quite distinctive. A
map showing the movement of the radiant can be found at
http://www.imo.net/calendar/2007.  According to the IMO, this minor shower
is probably linked to the Asteroid (4450) Pan.  Both visual plotting - and
telescopic observations - are encouraged.

The gamma Normids (GNO) start to become active about February 25th, although
won't reach a maximum until about March 14th. These are fast meteors, with
a velocity of about 56 km per second. ZHR rates at maximum will be about 4
meteors per hour, but rates in February will be lower. With a radiant about
30 degrees south of the top of the 'J' of Scorpius, this is primarily a
southern shower. A map showing the radiant can be found at
http://www.imo.net/calendar/2005/winter

The Antihelion Source (ANT), the ecliptical activity, produces a ZHR of
about 3 meteors per hour, with an average velocity of about 30 km per
second.  A map showing the movement of the radiant throughout the month can
be found at http://www.imo.net/calendar/2007

For other February 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 February'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   in southwest in evening twilight
Jupiter  -1.9   in Ophiuchus in morning sky
Mercury  -0.1   low in west-southwest in evening twilight
Saturn    0.0   in Leo
Mars      1.3   in Sagittarius in morning sky

The phases of the moon for February are as follows:
Fri. Feb. 2    full moon
Sat. Feb. 10   last quarter
Sat. Feb. 17   new moon
Sat. Feb. 24   first quarter

A monthly moon calendar can be printed off from
http://stardate.org/nightsky/moon.  For the NASA kids' calendar for the
month, go to http://spaceplace.nasa.gov/en/kids/calendar.shtml

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.

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 the NAMN Coordinator at
meteors at comcast.net

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.

Forms to record your observations can be found at
http://www.namnmeteors.org/namn_form.html and
http://www.namnmeteors.org/appendixC.html


3.  Upcoming Meetings...

June 11-15, 2007, Barcelona, Spain...

The Meteoroids 2007 conference will be held from June 11th to 15th at the
CosmoCaixa Museum in Barcelona, Spain, organized by the Institut d'Estudis
Espacials de Catalunya.

The preliminary scientific program includes the following sessions:
1. Observational techniques and meteor detection programs
2. Meteor showers' activity and forecasting
3. Orbits of meteoroids and dust
4. Meteoroids' interactions with atmospheres
5. Atmospheric effects induced by meteors
6. Astromineralogy:  properties of meteoroids
7. Interrelationships:  meteoroids - IDPs - dust - micrometeorites -
   meteorites
8. Meteoroid flux and impact hazard
9. Meteor studies in astrobiology

Invited speakers include Diego Janches, Pavel Spurny, Douglas ReVelle, Peter
Brown, Jeremie Vaubaillon, Junichi Watanabe, Peter Jenniskens, P.A. Wiegert,
I. Williams, Olga Popova, Lars Dyrud, John Plane, Nick Mitchel, Frans J.M.
Rietmeijer, Jiri Borovicka, George Flynn, Matthew Genge, Clark Chapman, M.E.
Sansaturio, Jose L. Ortiz, Joseph A. Nuth III, Josep M. Trigo-Rodriguez, and
Alessandra Rotundi.

For more information, check out the Meteoroids 2007 website at
http://www.spmn.uji.es/meteoroids-2007, or contact Dr. Josep M.
Trigo-Rodriguez at trigo at ieec.uab.es

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


4.  For more info...

NAMN email: namn at namnmeteors.org
NAMN website: http://www.namnmeteors.org

Mark Davis, meteors at comcast.net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network

Cathy Hall, chall at cyberus.ca
Ottawa, Ontario, Canada
Writer, NAMN Notes

Lew Gramer, dedalus at alum.mit.edu
Homestead, Florida, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'

Kevin Kilkenny, namnfireball at earthlink.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 at alum.mit.edu

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Here's to 'Clear Skies' for February...

February 2007 NAMN Notes
written by Cathy Hall & edited by Mark Davis
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