20th October-my Birthday Meteors-favourable this year.....
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BAA electronic bulletin No. 00443 http://www.britastro.org/
======================================================================
ORIONID METEORS: ENHANCED ACTIVITY THIS YEAR?
The Orionid meteor shower will be active throughout the coming week and
until the end of October. One of two annual showers associated with Comet
1P/Halley (the other being the Eta Aquarids of early May), the Orionids are
a moderately active shower, usually producing observed rates in excess of 10
meteors/hr around their maximum.
In the years from 2006-2008, observers in North America, particularly,
reported higher-than-normal Orionid meteor rates, and this month there is
chance that enhanced activity may be observed again. With New Moon on
October 18 and First Quarter on October 26, there will be no interference
from moonlight this year.
In a recent IAU electronic telegram (CBET 1976: 20091017) Peter Jenniskens,
SETI Institute, reports that the strong Orionid meteor shower activity may
well repeat this year, according to M. Sato and J.-I. Watanabe (2007, PASJ
59, L21). They ascribed the enhanced activity in the period 2006-2008
activity to dust trails of comet 1P/Halley that were formed by meteoroids
ejected in the years -1400 and -11. The orbital evolution of the dust is
affected by the 1:5 to 1:8 mean-motion resonances with Jupiter. This
so-called "filament" component is expected to be in the Earth's path again
around Oct. 18-24 in 2009, giving rise to a higher-than-normal
Orionid-shower activity that is relatively rich in bright meteors. Thanks
to the filamentary nature of the debris stream laid down by the parent
comet, activity can vary markedly from one year to another: good rates can
be experienced if Earth encounters a rich meteoroid filament, but at other
times activity might seem disappointing.
Several sub-peaks are usually seen between October 20-22, and intervals of
slightly increased activity can be found even as late as October 27-28. Like
1P/Halley, stream meteoroids have a retrograde orbit around the Sun, meaning
that they enter the upper atmosphere on 'head on' collisions at the high
velocity of 66 km/sec. Orionid meteors are very swift, and the brighter
ones, particularly, often leave behind brief persistent ionisation trains.
Having been laid down over numerous returns of 1P/Halley, the Orionid meteor
stream is quite spread out, and this is reflected in the shower's diffuse
(probably multiple) radiant. Orionid meteors emanate from a region of sky
midway between Betelgeuse (Orion's eastern 'shoulder') and the
second-magnitude star Gamma Geminorum. The radiant doesn't rise until 22h
local time, and best rates are generally found in the early morning hours
once it has gained somewhat in altitude.
Observations of the Orionid meteor shower should be made according to the
standard methods of the BAA Meteor Section which are available on the
Section's website at http://www.britastro.org/meteor
Please submit your observations to the BAA Meteor Section as soon as
possible after you have made them, and at any rate within one month at the
most. Observations should be sent to the Acting Director:-
Dr John Mason, 51 Orchard Way, Barnham, West Sussex PO22 0HX. Tel: 01243
814307. email docjohn@dircon.co.uk
The Acting Director will also be pleased to answer any queries regarding
further aspects of meteor work.
John W. Mason
BAA Meteor Section
18 October 2009
======================================================================
BAA electronic bulletins service. E-mail: circadmin@britastro.org
Bulletin transmitted on Mon Oct 19 18:05:58 BST 2009
(c) 2009 British Astronomical Association http://www.britastro.org/
======================================================================
--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
--
Web: http://lyra.freewebsites.com/
======================================================================
BAA electronic bulletin No. 00443 http://www.britastro.org/
======================================================================
ORIONID METEORS: ENHANCED ACTIVITY THIS YEAR?
The Orionid meteor shower will be active throughout the coming week and
until the end of October. One of two annual showers associated with Comet
1P/Halley (the other being the Eta Aquarids of early May), the Orionids are
a moderately active shower, usually producing observed rates in excess of 10
meteors/hr around their maximum.
In the years from 2006-2008, observers in North America, particularly,
reported higher-than-normal Orionid meteor rates, and this month there is
chance that enhanced activity may be observed again. With New Moon on
October 18 and First Quarter on October 26, there will be no interference
from moonlight this year.
In a recent IAU electronic telegram (CBET 1976: 20091017) Peter Jenniskens,
SETI Institute, reports that the strong Orionid meteor shower activity may
well repeat this year, according to M. Sato and J.-I. Watanabe (2007, PASJ
59, L21). They ascribed the enhanced activity in the period 2006-2008
activity to dust trails of comet 1P/Halley that were formed by meteoroids
ejected in the years -1400 and -11. The orbital evolution of the dust is
affected by the 1:5 to 1:8 mean-motion resonances with Jupiter. This
so-called "filament" component is expected to be in the Earth's path again
around Oct. 18-24 in 2009, giving rise to a higher-than-normal
Orionid-shower activity that is relatively rich in bright meteors. Thanks
to the filamentary nature of the debris stream laid down by the parent
comet, activity can vary markedly from one year to another: good rates can
be experienced if Earth encounters a rich meteoroid filament, but at other
times activity might seem disappointing.
Several sub-peaks are usually seen between October 20-22, and intervals of
slightly increased activity can be found even as late as October 27-28. Like
1P/Halley, stream meteoroids have a retrograde orbit around the Sun, meaning
that they enter the upper atmosphere on 'head on' collisions at the high
velocity of 66 km/sec. Orionid meteors are very swift, and the brighter
ones, particularly, often leave behind brief persistent ionisation trains.
Having been laid down over numerous returns of 1P/Halley, the Orionid meteor
stream is quite spread out, and this is reflected in the shower's diffuse
(probably multiple) radiant. Orionid meteors emanate from a region of sky
midway between Betelgeuse (Orion's eastern 'shoulder') and the
second-magnitude star Gamma Geminorum. The radiant doesn't rise until 22h
local time, and best rates are generally found in the early morning hours
once it has gained somewhat in altitude.
Observations of the Orionid meteor shower should be made according to the
standard methods of the BAA Meteor Section which are available on the
Section's website at http://www.britastro.org/meteor
Please submit your observations to the BAA Meteor Section as soon as
possible after you have made them, and at any rate within one month at the
most. Observations should be sent to the Acting Director:-
Dr John Mason, 51 Orchard Way, Barnham, West Sussex PO22 0HX. Tel: 01243
814307. email docjohn@dircon.co.uk
The Acting Director will also be pleased to answer any queries regarding
further aspects of meteor work.
John W. Mason
BAA Meteor Section
18 October 2009
======================================================================
BAA electronic bulletins service. E-mail: circadmin@britastro.org
Bulletin transmitted on Mon Oct 19 18:05:58 BST 2009
(c) 2009 British Astronomical Association http://www.britastro.org/
======================================================================
--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
--
Web: http://lyra.freewebsites.com/
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