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(meteorobs) Excerpts from "CCNet DIGEST 14 April 1999"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet DIGEST 14 April 1999
Date: Wed, 14 Apr 1999 14:00:12 -0400 (EDT)
CCNet DIGEST 14 April 1999
--------------------------
[...]
(3) INTERNATIONAL WORKSHOP ON COMETARY ASTRONOMY
Jonathan Shanklin <jdsh@mail.nerc-bas.acdot uk>=20
(4) A WILD RIDE IN SEARCH OF METEORS
NASA Science News <expressnews@sslab.msfc.nasadot gov>=20
(5) SURVEY FINDS NEARLY 800 DEBRIS IMPACTS ON HUBBLE=20
Ron Baalke <BAALKE@kelvin.jpl.nasadot gov> wrote:
[...]
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(3) INTERNATIONAL WORKSHOP ON COMETARY ASTRONOMY
>From Jonathan Shanklin <jdsh@mail.nerc-bas.acdot uk>=20
Dear Benny,
=20
Could you post the following to CCNet, I think the workshop should be=20
of general interest.
=20
Regards,
=20
Jon Shanklin
j.shanklin@bas.acdot uk
British Antarctic Survey, Cambridge, England
http://www.nbs.acdot uk/public/icd/jds
=20
The British Astronomical Association Comet Section is very pleased to=20
be hosting the second International Workshop on Cometary Astronomy. =20
This will be held at New Hall Cambridge from August 14 to 16. The=20
meeting aims to bring together professional and amateur observers and=20
as many comet discoverers as possible.
=20
The first IWCA was held at Selvino, Italy in February 1994. Four=20
previous American Workshops on Cometary Astronomy had been held in the=20
U.S.A., but had not attracted much attention in Europe.
=20
The 1994 meeting marked the 15th anniversary of the International Comet =
Quarterly and attracted a good attendance of active observers. =20
Presentations on the work of various national observing groups were=20
given, along with talks by individuals on their own particular=20
programs. Of greater importance were sessions which focussed on=20
observing methodologies and these lead to significant improvements in=20
the quality of observations.
=20
Since then we have had two very bright comets which presented new=20
problems in observation. There has been a huge growth in the Internet,=20
enabling rapid dissemination of observations and the suspicion that=20
this may bias observers. Planetarium programs using the Guide Star=20
Catalogue now give observers precise finder charts enabling them to=20
observe much fainter comets than in the past.
=20
These new problems need new solutions and hopefully discussion at the=20
meeting will lead to some conclusions that further improve our=20
observing standards. However, observers generally have very fixed views =
so expect some heated arguments!
=20
Although many amateurs observe comets for their own satisfaction, it=20
can add enjoyment if you know that your observations are contributing=20
to the scientific understanding of comets. To this end a number of=20
leading professionals will be at the meeting, explaining how our=20
observations are used and what additional observations would help with=20
their research.
=20
Bearing all this in mind the meeting has three main goals: 1) improving =
the acquisition of cometary information. 2) increasing understanding as =
to what science can be gained through observing comets by both=20
amateurs and professionals. 3) providing a forum in which cometary=20
astronomers can meet others from distant geographical locations and=20
discuss various issues.
=20
The format of the meeting will be to have selected invited talks, open=20
panel discussions, contributed talks and poster sessions. Speakers=20
scheduled to appear include Doug Biesecker (SOHO comets), Nicolas Biver =
(visual magnitudes and CO outgassing beyond 3 AU), Stephane Garro=20
(French archival observations), Dan Green (comet photometry), Eleanor=20
Helin (comet searching/discovery at Palomar and with NEAT), Gary Kronk=20
(on his forthcoming Cometography), Brian Marsden (amateur=20
contributions), Herman Mikuz (CCD photometry), Charles Morris (possibly =
on web issues), Mahendra Singh (comet spectroscopy).
=20
The college bar will be open in the evenings for informal discussion. =20
If it is clear there will be opportunity to use the two historic=20
refractors at the University Observatory.
=20
Cambridge has many sites of astronomical interest and there will be=20
free time for participants to explore at their leisure. Many famous=20
scientists with comet connections studied at Cambridge including=20
Newton, Herschel, Challis and more recently Lyttleton.
=20
To conclude the meeting I have arranged a trip to Stonehenge on the=20
Monday evening, when we will be allowed in to the inner circle to view=20
the stones close up. There have been some suggestions that Stonehenge=20
was first constructed as either a comet or meteor observatory! Numbers =
for this visit have to be restricted and those attending the meeting=20
will have priority.
=20
Further details about the meeting are available on the Section web page =
at http://www.astdot cam.acdot uk/~jds
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(4) A WILD RIDE IN SEARCH OF METEORS
>From NASA Science News <expressnews@sslab.msfc.nasadot gov>=20
NASA Space Science News for Apr 14, 1999
=20
A Wild Ride in Search of Meteors: On April 11, NASA scientists=20
successfully launched a weather balloon designed to capture meteoroids=20
in the stratosphere. The primary payload, a xerogel micrometeoroid=20
collector, has been recovered and returned to the Marshall Space Flight =
Center for analysis. This story features video highlights from the=20
flight including the sunset as seen from 80,000 ft. and eerie gurgling=20
sounds caused by high altitude winds. =20
FULL STORY at
http://science.nasadot gov/newhome/headlines/ast14apr99_1.htm
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
(4) ARMAGEDDON IN ANTARCTICA
=20
>From the BBC Online Network
http://news.bbc.codot uk/hi/english/sci/tech/newsid_317000/317410.stm=20
Tuesday, April 13
=20
By BBC News Online Science Reporter Damian Carrington=20
=20
Icebergs crashing against the sea floor could be the most devastating=20
natural disaster that any living community on Earth experiences.=20
=20
Scientists from the British Antarctic Survey have discovered that over
99.5% of all visible sea-bed dwellers are massacred when the bergs=20
collide with the ocean bottom.=20
=20
Floods, earthquakes and even meteorite impacts cannot claim such total=20
destruction. The project leader, Professor Lloyd Peck, told BBC News=20
Online: "In biological terms it is outrageous - it's almost a sterile
environment."=20
=20
Up to 20% of the world's oceans are prone to catastrophic ice berg=20
impacts. Even ocean floor as deep as 500m is at risk.=20
FULL STORY at
http://news.bbc.codot uk/hi/english/sci/tech/newsid_317000/317410.stm
=20
Copyright 1999, BBC
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(5) SURVEY FINDS NEARLY 800 DEBRIS IMPACTS ON HUBBLE=20
>From Ron Baalke <BAALKE@kelvin.jpl.nasadot gov> wrote:
http://www.astronomynow.com/breaking/990412debris/index.html
=20
Survey finds nearly 800 debris impacts on Hubble
FROM NASA'S ORBITAL DEBRIS QUATERLY NEWS
Posted: April 12, 1999
=20
During the second servicing mission of the Hubble Space Telescope (HST) =
by the STS-82 mission in February, 1997, an extensive imagery survey=20
was performed covering approximately 97% of the HST surface. The=20
results of a dedicated study to identify and to characterize apparent=20
micrometoeoroid and orbital debris (M/OD) impacts have been recently=20
documented in a new NASA JSC report, "Survey of the Hubble Space=20
Telescope Micrometeoroid and Orbital Debris Impacts from Service=20
Mission 2 Imagery," by G.J. Byrne, D.R. Bretz, M.H. Holly, M.T. Gaunce, =
and C.A. Sapp.
=20
Employing video, photography, and electronic still imagery (a total of=20
2500 still frames and 17 hours of video), the analysis team was able to =
identify 788 potential impacts on the HST aft shroud, equipment=20
section, aft bulkhead, grapple fixtures, aperture door, and solar=20
arrays. The analysis process involved first screening and categorizing=20
the images, then imagery review and M/OD impact identification,=20
followed by mapping and measurements of the impact features.
Over 500 of the impacts were found on the aft shroud and equipment=20
section where highly reflective surfaces facilitated detection of=20
impact features. Approximately 80% of the impact zones measured less=20
than 0.8 cm, although the largest was 4.7 cm in diameter.
A plot of the number of impacts of a given outer diameter size range=20
illustrates the expected exponential increase down to a size of 0.4 -=20
0.5 cm, where sensitivity limits of the imagery apparently lead to a=20
reduced count. The distribution of impacts around the aft shroud=20
suggest a real difference in the number of particle impacts on the +V3=20
and the -V3 sides.
An attempt was also made to compare the number of impacts seen on the=20
first servicing mission in December 1993 (after 44 months exposure in=20
LEO) and the second servicing mission (after an additional 38 months=20
exposure in LEO). A limited comparison of the +V3 quadrant showed an=20
increase in the density of observed strikes from approximately 5=20
impacts per square meter to approximately 20 impacts per square meter.=20
While some of this increase is undoubtedly due to the superior quality=20
of the imagery obtained during the second servicing mission, a change=20
in the environment may also be indicated.
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
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please contact the moderator Benny J Peiser <b.j.peiser@livjm.acdot uk>.=20
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