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(meteorobs) NAMN Notes: November 2003



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NAMN Notes:  November 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.  Leonids - Debris from Comet Tempel-Tuttle...
2.  Alpha Monocerotids to Monitor...
3.  Other November Meteor Activity...
4.  The Comet Connection...
5.  Upcoming Meetings...
6.  For more info...


1.  Leonids - Debris from Comet Tempel-Tuttle...

For the past several years, Leonid meteor storms have delighted observers
around the globe.  What should we expect to see this year in 2003?

The meteor experts tell us that the storms are over - but that this shower
can still hold some surprises for us.  As is the case with all meteor
activity, you won't know what these surprises are unless you go out to
observe!

According to the International Meteor Organization's (IMO) 2003 Meteor
Shower Calendar, the Leonids (LEO) will reach a maximum on November
18th at 2h 30m UT.  For observers in eastern North America, this means
9:30 pm EST on Monday November 17th.  Leonids can be seen from about
November 14th to 21st.

At maximum, the radiant will be at 153 degrees, ie. RA 10h 12m,
Dec +22, which is up in the sickle of the constellation of Leo:
http://www.imodot net/calendar/cal02.html#Leonids.  These are fast meteors at
about 71 km per second.  ZHR rates are listed as 100+ in the calendar.  ZHR
stands for Zenithal Hourly Rate, and is the number of meteors that an
observer would expect to see, on average, if they were out under a dark
country sky, and if the radiant, the area of the sky where the meteors seem
to come from, is directly overhead.

The International Meteor Organization needs observations:

"Observers should be alert to covering whatever the shower produces, as
following the post-storm phases after this best-ever observed series of
storm returns is as vital to our understanding of the stream as seeing the
storms themselves... observers should be watching for as much of November
16-17 to 19-20 as conditions will allow, in case something unexpected
happens."

But wait!  Listen carefully.  Leonids can provide surprises.  What
predictions have the other experts been coming up with?

For starters, note that the traditional Leonid peak, as just mentioned, is
listed on the website of Peter Jenniskens and the Leonid MAC Team at
http://leonid.arc.nasadot gov/1998.html as November 18, 10h UT, plus or minus
2 hours, but a few days wide - with ZHR rates of only about 13 meteors per
hour.  Not everybody agrees on times or rates when it comes to meteor
showers.

In addition to the main Leonid activity, the experts have been studying
specific filaments or trails of debris.

Every 33.2 years, the parent comet of the Leonids, Comet Tempel-Tuttle,
passes around the sun in its orbit and sheds debris.  This debris takes on
a slightly different orbit from the parent comet - and the debris shed in
each subsequent comet return is laid down in a slightly different orbit.
Over the years, we end up with a number of filaments or trails of debris,
each in slightly offset orbits.  When the earth passes through this area in
space, it passes through a number of different trails at different times.

The researchers call each trail by the number of revolutions around its
orbit that the dust has made since being shed.  For example, the 8-rev
trail is the debris from 1733, the 14-rev trail is the debris from 1533,
15-rev from 1499, 20-rev from 1333, 38-rev from 736 and 41-rev from 636,
counting backwards through time!  Some trails will produce more meteors
than others. Some will have less debris in them and be almost
insignificant - and the researchers may not quote meteor rates from those.

Jeremie Vaubaillon and Francois Colas give 2003 predictions for Leonid
activity on their website at:
http://www.imcce.fr/s2p/leonides/predictions/Leonid_forecast_2003.html.
They give details on the Leonid meteor rates expected due to the earth's
encounter with the following old meteoroid streams:

Time of maximum      Expected ZHR        Trail
Nov. 13, 17:17 UT    120                 1499
Nov. 19, 07:28 UT    100 (?)             1533
Nov. 22, 22:02 UT    less than 10         736
Nov. 23, 02:56 UT    less than 10         636

Note that time is quoted in UT (Universal Time) which is also the time at
Greenwich, England.  For observers in North America on Eastern Standard
Time (EST), subtract 5 hours.  For other time zones, adjust accordingly.

Durations for these are given as:  1499 trail - several hours, 1533 trail -
about 1 hour, 736 trail - 1 hour at most, and 636 trail - several hours.
Due to these predicted short durations, geographical location and resultant
hours of darkness will be a factor.

Vaubaillon emphasizes (and we quote directly!):
"IT IS VERY IMPORTANT TO OBSERVE, EVEN IF THE LEVEL WILL NOT BE AS HIGH
AS IN PAST YEARS!"

2003 Leonid trail predictions are also discussed on the website of Peter
Jenniskens and the Leonid MAC team at http://leonid.arc.nasadot gov/1998.html.
This site has a wealth of information on the Leonid meteor shower and its
parent comet Tempel-Tuttle.  As quoted from the website regarding November
19th, 05:30 UT:

"According to Peter Jenniskens and Hans Betlem (2000, ApJ 531, 1161), many
other such old dust trails trapped in mean-motion resonances tend to form a
broad dust trail structure called the "FILAMENT".  The Filament is a sum of
contributions from many returns and the nature of individual dust trails
may not be recognized anymore... the structure will be very broad, about 1
day wide and underlays more recent dust trail encounters... rates in 2003
could increase to about ZHR = 50 per hour... rich in bright meteors...
Peter Jenniskens calculated an expected peak time around 5.5 UT, November
19, based on the trend observed in 1995-1997 and 1999-2002...  However, in
1994 and 1998 this peak was ~ 0.7 days earlier for unknown reasons."

Regarding November 13th, 13-19 UT:

"Esko Lyytinen and Tom van Flandern (2000, EMP 82-83, 149-166) have
predicted an encounter with the 15 revolution <1499> dust trail of comet
55P/Tempel-Tuttle on 2003, November 13.  That is five days earlier than the
usual Leonid showers!  Peak of the shower is around 13-19 UT...  Rates
could increase to peak at ZHR = 250 per hour.  The prediction is uncertain,
because it assumes that dust is trapped in the 5:15 (= 1:3) mean-motion
resonance with Jupiter, instead of the 5:14 resonance.  Because of this
difference, the dust will have completed 14 orbits, when the comet itself
has completed 15 orbits."

In private correspondence with C. Hall, Esko Lyytinen provided the
following comments on the Leonid predictions this year:

"... Jeremie Vaubaillon, David Asher and Markku Nissinen and myself <are>
submitting a paper to WGN...  In general we (authors of the WGN paper)
agree on the trails to be encountered.  There are small differences on the
timing, but not serious...  As to the predicted rates, I predict ZHR about
100 to the 1499 trail encounter and maybe only dozen(s) to the 1533 trail
encounter.  With the 736 trail encounter I agree with Jeremie's <=10."

When C. Hall inquired as to the ZHR 100 vs. 250 for the November 13th, 1499
trail as quoted on the Jenniskens website, Lyytinen replied:

"Yes, we had this a little stronger in our earlier paper in the journal
Earth Moon and Planets, in 2000.  The prediction (of the trail 1499) is
however quite uncertain, because of very old trail and actually an
encounter with a trail with a loop, encountering actually twice, one
more a dense section and also more distant.  This also makes the timing
of maximum uncertain.  These are expected to appear as one outburst, but
depending which one is stronger affects the timing.  This is expected to
last for about half a day, so an exact timing-prediction may not be so
important. This might quite well be at the ZHR 200 to 300 level, but more
probably at the 100 level."

"In all the 1499 and 1533 trails will produce mostly dim meteors, so there
may be a stronger outburst of more dim meteors detected by radio forward
scatter or telescopically."

"The 1333 trail brightnesses would be a little better something like the
7-rev. encounter in 2002.  The 736 (and probably 636, although I have no
data for this) are expected to give more bright meteors, but sorry not with
a high ZHR."

"In all, the old trail-predictions around 600-700's may be unreliable
because of uncertainties in the comet motion so far back in time.  It may
however be that if some of these trails (636 or 736) fails to give anything
there may (?) be some other trails substituting this.  Because the
predictions for the trails 636 and 736 are for the same night (... night
here in Europe) 22/23, it may well be that the possible 'substituting'
trails will also get encountered this night.  At least the meteors from the
736 trail are expected to be mostly bright (bolides), so there is the
POSSIBILITY that this night may have bolides with ZHR of a few dozens
(hopefully even better)."

"Then I think it possible to see something from the 8 rev trail encounter
<1733>, but this is IF there are quite strong non- gravitational effect
affecting.  This may (also) give a ZHR of a few dozens, if any.  The
observations of this may however have importance.  This is predicted 19
Nov. at about 00:25 UT."

"Then, I only yesterday evening paid attention to my old graph that seemed
to have some level encounter with the trail from 1333.  (I have probably
noticed this earlier but not paid attention, while waiting the real storms
a few years back.)  Actually this is not a bad encounter, but because of so
old, my 'ZHR-base model' gave a ZHR of about 20 to 25.  (The base model
doesn't take into account special non gravitational effects.  For young
trails these effects need not to be taken into account.  For old trails the
effect typically decreases the value, but may also increase.)  I don't have
any better than this value, and may not have even before November.  (It
would take several computer runs and manual time to make a more complete
model."

"Of all this year encounters, I have only made the more complete
model from the 1499 trail-encounter.  With the 8-rev. <1733> trail some of
the computer runs of such a model are done, or actually were done for the
year 2000 encounter, but not for the whole model (that would anyway be non
reliable because of the relevant almost-extreme effect-values).  This is
from where I found this.)"

Time of maximum            Expected ZHR                        Trail
Nov. 13, about 17h UT      100                                  1499
Nov. 19, 00:25 UT          possibly 20, possibly nothing        1733
Nov. 19, 08h UT            20 or maybe less                     1533
Nov. 20, 01:30 UT          10 - 20                              1333
Nov. 22, 21h UT            about 10                              736

"Then there may be (and almost probably will be) something surprising.
There may be something along the lines that Peter Jenniskens expects
(filament), (although I don't agree with all the details (or groundings)
that he gives behind this)."

Many thanks go to Esko Lyytinen for providing all these comments on Leonid
predictions this year for our NAMN readers!

In private correspondence with C. Hall, David Asher also provided some
information.  As the paper on the 2003 Leonid shower submitted to WGN is
not released yet, and is a collaborative paper between 4 different
researchers (Vaubaillon, Lyytinen, Nissinen and Asher), we will give
only some selected comments from this paper, reference "WGN, in press":

According to David Asher and Rob McNaught:

Time of maximum     Trail
Nov. 13, 13:15 UT    1499
Nov. 13, 18:20 UT    1499
Nov. 19, 06:30 UT    1533
Nov. 20, 00:50 UT    1333

"There is a lot of fine structure in old trails, and when the original dust
trail calculation method is applied to the 1499 trail, multiple encounters
are found... the former is closer to the Earth's orbit although both
nominally miss the Earth by well over ten Earth diameters.... "

And from the general comments in the 2003 Leonid shower paper, reference
"WGN, in press":

"It is worth mentioning that the differences for very old streams seen in
these predictions <between researchers> result from different cometary
elements at time of ejection."

What is actually a very interesting comment in the paper is:  "Although an
accurate orbit for the comet is the essential input parameter to the trail
encounter calculations, observing the meteors may conversely provide
information on the time of perihelion of comet 55P/Tempel-Tuttle a long
time ago, by showing which of two possible orbits <used by different
researchers> better matches the observations...  we encourage everybody to
conduct some observations if possible.  They will again help to constrain
the models of the streams, and also give information on the orbit of the
parent body more than 1000 years ago."

Thanks go to David Asher for a preview of the article coming out in WGN,
and permission to use several comments!

In summary, there is important information to be learned from all
observations of the Leonids this year - whatever your location, or date and
time of your observations.  We need as many observers as possible around
the globe to monitor Leonid activity and help us contribute to a better
understanding of this shower - and of its parent body, Comet Tempel-Tuttle!

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

The information to record while observing includes data for each
meteor, such as time it occurred, magnitude (brightness), shower it belongs
to, 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.  A set of star maps showing the
standard stars we use to help in judging meteor magnitudes can be printed
off from http://www.namnmeteors.org/charts.html  Any questions on what to
record, or how, can be sent to our NAMN Coordinator at meteors@comcastdot net

For more news as it happens stay tuned to our MeteorObs email list.  Some
of you will be receiving this newsletter by independent email.  MeteorObs
is an email discussion list frequented by observers all around the globe.
Around Leonid time it will provide many valuable answers to all your
questions.  To sign up - even if you just want to listen in during the
Leonids - fill in the online subscribe form on the MeteorObs website at
http://www.meteorobs.org/subscribe.html.  You can unsubscribe at any time
by using the same form.

Clear skies to all - and good luck on your observations of the 2003
Leonids!


2.  Alpha Monocerotids to Monitor...

The alpha Monocerotids (AMO) reach a maximum on November 22nd this year,
with a radiant at 117 degrees, ie. RA 7h 48m, Dec +01.  A map showing the
radiant position for this meteor shower can be found at
http://www.imodot net/calendar/cal01.html#alpha-Monocerotids.  These are fast
meteors with a velocity of about 65 km per second, and can be seen from
about November 15th to 25th.  The time of maximum is listed as November
22nd 2h 45m UT.  For observers in eastern North America, this means 9.45 pm
EST
on the night of Friday November 21st.  The ZHR rate is listed as variable.

This meteor shower can produce surprises - so should be watched closely.
In 1995, there was an outburst of 400 or more meteors per hour.  It has
been suggested that there may be a 10-year periodicity for this shower, so
your
observations are needed!

The IMO states that "all observers should continue to monitor this source
closely... new moon on November 23 makes this an ideal year for detailed
scrutiny."


3.  Other November Meteor Activity...

Besides the Leonids and the alpha Monocerotids there is other meteor
activity to keep a watch for in November as well.  To help in locating
these other radiants in the sky, print yourself off a set of our NAMN star
charts from http://www.namnmeteors.org/charts.html

The Orionids (ORI), although having reached a maximum back on October 21st,
can still be seen until about November 7th.  These are fast meteors at
about 66 km per second.  ZHR rates in October were about 20 meteors per
hour but rates in November will be lower.  A map showing the radiant can be
found at http://www.imodot net/calendar/cal01.html#Orionids.  These meteors
are debris from Halley's Comet - some photos of the comet can be found on
Kronk's 'Cometography' website at http://cometography.com/pcomets/001p.html

The southern Taurids (STA) reach a maximum on November 5th with a radiant
at 52 degrees, ie. RA 3h 28.2m , Dec +13 on a star map.  These are slow
meteors at about 27 km per second.  They can be seen until about November
25th.  ZHR rates at maximum are about 5 meteors per hour.

The northern Taurids (NTA) reach a maximum a week later on November 12th,
with a radiant at 58 degrees, ie. RA 3h 52.2m, Dec +22 on your star map.
For a map showing both the Taurid radiants, check out
http://www.imodot net/calendar/cal02.html#Taurids.  The northern Taurids are
also slow meteors with a velocity of about 29 km per second.  They can be
seen until about November 25th as well.  Like the southern Taurids, the ZHR
rate is about 5 meteors per hour.

Both the northern and the southern Taurids are part of the Taurid stream
which has been associated with Comet Encke.  The Taurids have a "reputation
for producing some excellently bright fireballs at times" according to the
IMO.  In their 2003 Calendar they state:

"The late October to early November spell, which sometimes seems to produce
more or brighter Taurids, is mostly free from moonlight this year however.
David Asher has suggested such enhanced activity may be due to a denser
'swarm' of larger Taurid particles within the stream, and two recent such
events in 1995 and 1998 provide some support for this.  Though the next
October-November 'swarm' return is not predicted until 2005, this would be
a good year to check for any additional unusual activity."

The chi Orionids (XOR) start to become active about November 26th, although
won't reach a maximum until December 2nd when their radiant will be at 82
degrees, ie. RA 5h 28.2m, Dec +23.  A map showing the radiant can be found
at http://www.imodot net/calendar/cal02.html#chi-Orionids.  These are slow
meteors with a velocity of about 28 km per second.  ZHR rates at maximum
will be about 3 meteors per hour with rates lower prior to that.  According
to the IMO, this is "a weak visual stream, but one moderately active
telescopically.  Some brighter meteors have been photographed from it too.
The shower has at least a double radiant, but the southern branch has been
rarely detected."

The Monocerotids (MON) start to become active about November 27th, although
won't reach a maximum until December 9th when the radiant will be at 100
degrees, ie. RA 6h 40.2m, Dec +08.  These are average velocity meteors at
about 42 km per second.  ZHR rates at maximum in December will be about 3
meteors per hour but rates in late November will be less.

Lastly, the December Phoenicids (PHO) start to become active about November
28th, although the maximum is not until December 6th.  The radiant on the
6th will be at 18 degrees, ie. RA 1h 12m, Dec -53.  A map of the radiant
can be found at http://www.imodot net/calendar/cal02.html#Phoenicids.  These
are
really slow meteors with a velocity of about 22 km per second, so will be
quite distinctive.  ZHR rates for this shower are variable, usually only
about 3 meteors per hour or less - but they have been known to reach about
100 meteors per hour.  Observers at more southerly latitudes should
definitely monitor this shower!

Besides recognized main showers and other minor showers, there is also
sporadic meteor activity in November.  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:
Sat. Nov. 1     first quarter
Sun. Nov. 9     full moon
Mon. Nov. 17    last quarter
Sun. Nov. 23    new moon
Sun. Nov. 30    first quarter

Planets at midmonth, and their magnitudes, for northern observers, are:
Mars       -0.9  in Aquarius
Saturn     -0.1  in Gemini
Jupiter    -1.9  in Leo, in morning sky
Venus      -3.9  very low in west in evening

The planets are very good standards for estimating the magnitude of bright
meteors.  For a map showing the planets' positions in your sky, go to
http://www.heavens-above.com  and Select your location, then go to 'Whole
Sky Chart'.  Note that on the night of November 8/9, there will be a total
eclipse of the moon.  The entire eclipse will be visible from Europe and
most of Africa, as well as eastern North and South America.  Other
locations will see the eclipse for various stages only.  For more details,
check out the Sky and Telescope website at http://skyandtelescope.com  once
it is updated for November.


4.  The Comet Connection...

Many of our meteor showers have as their parent body a comet.  Some we
know about and have identified, such as Comet Tempel-Tuttle and the
Leonids - and Comet Encke and the Taurid meteoroid stream.  Others are as
yet unknown.  In other cases, such as the Geminids in December, the parent
body has been identified as an asteroid - Phaethon.

In fact, Comet Encke is visible to amateur astronomers this month!
Information and coordinates for the comet can be found on the Harvard
website at http://cfa-www.harvarddot edu/iau/Ephemerides/Comets/0002P.html.
There is a link to the daily coordinates which you will need to refer to.
Comet Encke was only the 2nd comet found to be periodic, hence its
designation as Comet 2P/Encke.  According to Sky and Telescope, "this is
the 59th observed passage of Comet Encke, whose appearances date back to
when
it was first seen by French observer Pierre Mechain in 1786...  Comet Encke
is
closest to Earth in mid-November, passing our planet at 0.26 astronomical
unit (39 million kilometers)."  Check out the article 'The Changing Face of
Comet Encke' by Greg Bryant, on the Sky and Telescope website at
http://skyandtelescope.com/observing/objects/comets/article_1036_1.asp

More information on the comets and asteroids in our skies can be found at
the following sites:

Weekly Information about Bright Comets, by Seiichi Yoshida:
http://www.aerithdot net/comet/weekly/current.html

Comet Rendezvous Calendar, by Seiichi Yoshida:
http://www.aerithdot net/comet/rendezvous/current.html

Ephemerides of Observable Comets (includes daily coordinates):
http://cfa-www.harvarddot edu/iau/Ephemerides/Comets/index.html

British Astronomical Association Comet Section:
http://www.astdot cam.acdot uk/~jds/

Gary Kronk's Cometography:
http://cometography.com/

Sky & Telescope - Comets:
http://skyandtelescope.com/observing/objects/comets/

Sky & Telescope - Asteroids:
http://skyandtelescope.com/observing/objects/asteroids/

The Asteroid/Comet Connection - Major News about Minor Objects:
http://www.hohmanntransfer.com/news.htm

Lastly, congratulations go out to Vello Tabur, an amateur astronomer who
has just discovered a new comet!  The story of his comet discovery, the
first
CCD comet he has found since giving up visual searches in 1998, can be
found at http://www.tipdot net.au/~vello/2003t3/2003t3.htm


5. 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, 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.

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


6.  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 November...

November 2003 NAMN Notes
written by Cathy Hall & edited by Mark Davis
==============================================















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