[meteorite-list] Leonids 2003 - more info

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From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:28:32 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4EE58_at_US-Torrance.mail.saic.com>

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Hi Robert, Steve and List,

I'm still digging to get some best estimates of hourly rates, but here is
what I have
so far for the 2003 Leonids.

There are three peaks:

1. Nov. 13 17:17 UT (12:17pm EST, 11:17am CST, 10:17am MST, 9:17am PST).
Clearly this one does not favor the U.S. as it occurs in the middle of the
day.
Europe is also out since the radiant will not have risen yet. Asia,
Australia and
New Zealand are the places to be. This peak is associated with the Tempel-
Tuttle dust trail shed in 1499. Hourly rate around 100; however, the Moon
will
be a waning gibbous and thus will interfere with the early morning view.

2. The second peak is very broad -- perhaps as long as 24 hours, meaning
everyone has a chance to observe a portion of it. The approximate center of
this "peak" is 5:25 UT on Nov. 19th (12:25am EST, 11:25pm CST on 11/18,
10:25pm MST on 11/18, and 9:25pm PST on 11/18). The peak time favors
western Africa, western Europe, eastern Canada and the northeast U.S.,
though locations east of [earlier] or west of [later] these may be nearly as
good. Since nearly a week has passed since the first Leonid peak, the
Moon is much less of a factor -- just a thin crescent. The reason this peak
is so broad is that it consists of a mish-mash of contributing dust streams
laid down over centuries. The hourly rate may not be as great as the first
peak (60 per hour?) but Peter Jenniskens (NASA Ames) and Hans Betlem
(Dutch Meteor Society) interestingly predict that it will be rich in bright
fireballs.

3. Nov. 19 7:28 UT (2:28 am EST, 1:28am CST, 12:28am MST, 11:28pm PST
on Nov. 18th). The third peak favors North America and much of South
America.
This dust trail is from the 1533 comet orbit. The peak will probably not be
as great as the first (I've read estimates from 30 to 100) and the number of
bright meteors is expected to be low, meaning urban locations will see very
few. In light of this, and given that the peak is only a couple hours after
the
2nd broad peak, I predict that there may not be enough of a blip in the
meteor
rate (above the background of the second peak) to detect it as a separate
entity.

Best,
Rob

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<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>Hi
Robert, Steve and List,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>I'm
still digging to get some best estimates of hourly rates, but here is what I
have</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>so
</SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>far for the 2003 Leonids.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>There
are three peaks:</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>1.  Nov. 13 17:17 UT (12:17pm EST, 11:17am CST,
10:17am MST, 9:17am PST).</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>Clearly this one does not favor the U.S. as it occurs
in the middle of the day.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>Europe
is also out since the radiant will not have risen yet.  Asia, Australia
and</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>New
Zealand are the places to be.  This peak is associated with the
Tempel-</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>Tuttle
dust trail shed in 1499.  Hourly rate around 100; however, the Moon
will</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>be a
waning gibbous and thus will interfere with the early morning
view.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>2. The
second peak is very broad -- perhaps as long as 24 hours,
meaning</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>everyone has a chance to observe a portion of it. 
</SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>The approximate center of</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>this
"peak" is </SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>5:25 UT on </SPAN></FONT><FONT color=#0000ff face=Arial
size=2><SPAN class=167503117-20102003>Nov. 19th (12:25am EST, 11:25pm CST on
11/18,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>10:25pm MST on 11/18, </SPAN></FONT><FONT color=#0000ff
face=Arial size=2><SPAN class=167503117-20102003>and 9:25pm PST on 11/18). 
The peak time favors</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>western </SPAN></FONT><FONT color=#0000ff face=Arial
size=2><SPAN class=167503117-20102003>Africa, western Europe, eastern Canada and
the northeast U.S.,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>though
locations east of [earlier] or west of [later] these may be nearly
as</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>good.  </SPAN></FONT><FONT color=#0000ff
face=Arial size=2><SPAN class=167503117-20102003>Since nearly a week has passed
since the first Leonid peak, the</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>Moon
is </SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>much less of a factor -- just a thin crescent. 
The reason this peak</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>is so
</SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>broad is that it consists of a mish-mash of
contributing dust streams</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>laid
</SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>down over centuries.  The hourly rate may not be
as great as the first</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>peak
(60 per hour?) but Peter Jenniskens (NASA Ames) and Hans
Betlem</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>(Dutch
Meteor Society) interestingly predict that it will be rich in
bright</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>fireballs.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>3.  Nov. 19 7:28 UT (2:28 am EST, 1:28am CST,
12:28am MST, 11:28pm PST</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>on
Nov. 18th).  The third peak favors North America and much of South
America.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>This
dust trail is from the 1533 comet orbit.  The peak will probably not
be</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>as
great as the first (I've read estimates from 30 to 100) and the number
of</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>bright
meteors is expected to be low, meaning urban locations will see
very</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>few.  In light of this, and given that the peak is
only a couple hours after the</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=167503117-20102003>2nd
broad peak, I predict that </SPAN></FONT><FONT color=#0000ff face=Arial
size=2><SPAN class=167503117-20102003>there may not be enough of a blip in the
meteor</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>rate</SPAN></FONT><FONT color=#0000ff face=Arial
size=2><SPAN class=167503117-20102003> (above the background of the second peak)
to detect it </SPAN></FONT><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>as a separate</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>entity.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>Best,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003>Rob</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=167503117-20102003></SPAN></FONT> </DIV></BODY></HTML>

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Received on Mon 20 Oct 2003 02:19:23 PM PDT

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