I understand from time to time Asteriods occult stars.
Two questions:
- What was the brightess star that has been observed to
  have been occulted by an asteriod?
- What was the longest time that a star has been observed to have been  
  occulted by an asteriod? 

Cheers

Mongolia

---

Request for Question Clarification by pinkfreud-ga on 24 Jan 2005 20:19 PST

These questions aren't boring at all (at least, not to me). I'm
posting what I found for you, even though I wasn't able to answer both
of your questions.

The brightest star ever observed to have been occulted by an asteroid
is Alhena (Gamma Geminorum):

"A subgiant A star and the third brightest member of Gemini. Its
Arabic name (alternatively given as Almeisan) refers to a brand on a
horse or a camel. Alhena is a spectroscopic binary with a period of
12.6 years and is the brightest star ever observed to be occulted by
an asteroid. In 1991, (381) Myrrha passed in front of Alhena enabling
not only the asteroid?s diameter (140 km) to be determined but also
the fact that the dimmer companion star is a Sun-like G star almost
200 times fainter than Alhena proper."

The Encyclopedia of Astrobiology, Astronomy, and Spaceflight 
http://www.daviddarling.info/encyclopedia/A/Alhena.html

"Alhena is also the brightest star ever observed to be occulted
(crossed over, eclipsed) by an asteroid, the minor planet 381 Myrrha
in 1991, the crossing time leading to an asteroidal diameter of 140
kilometers. The occultation revealed the fainter companion to be
almost 200 times fainter than Alhena proper and to be a main sequence
(hydrogen-fusing) G star like the Sun. From the accumulated
observations, the companion, of about one solar mass, orbits the 2.8
solar mass primary (Alhena) at an average separation of about 8.5
astronomical units (Earth-Sun distances), about the size of the orbit
of Saturn. The orbit, however, is very elliptical, taking the little
one from about as close as Earth is to the Sun to what would be close
to the orbit of Uranus."

Portraits of Stars and their Constellations
http://www.astro.uiuc.edu/~kaler/sow/alhena.html 

"The brightest naked eye event was the Gamma Geminorum occultation by
(381)Myrrha in 1991."

The Society for Popular Astronomy
http://www.popastro.com/sections/occ/obs2004.htm

Here you'll find a list of observed occultations of stars by asteroids
(through 2002):

OBSERVED MINOR PLANET OCCULTATION EVENTS 
http://sorry.vse.cz/~ludek/mp/world/mpocc1.txt

I have been unable to find the answer to your second question about
the event with the longest duration. The Researcher who comes up with
that information can claim the prize.

---

Clarification of Question by mongolia-ga on 27 Jan 2005 19:04 PST

Pinkfreud 

Many thanks for the information you have given me which I find very 
interesting.

I found the last two websites you mentioned especially good

OBSERVED MINOR PLANETS OCCULTATION EVENTS
and the one as part of your comments which list future events
for 2007 and 2008.

Just a couple more quick questions regarding
 OBSERVED MINOR PLANETS OCCULTATION EVENTS
 - What are the 3 columns under Chords?
 - do any of the columns give the actual Occultation times
Mongolia
PS Please regard my initial questions fully answered.

---

Request for Question Clarification by pinkfreud-ga on 27 Jan 2005 21:20 PST

I have found a much more recent version of the document on asteroidal occultations:

OBSERVED MINOR PLANET OCCULTATION EVENTS
http://www.lunar-occultations.com/iota/asteroids/obserlst.htm

I confess I do not know what the columns under "Chords" might mean. I
am fascinated by astronomy, but often my knowledge is eclipsed by my
ignorance.

Here are predictions for the first quarter of 2005 that may interest you:

IOTA Asteroidal Predictions - 1st Quarter - 2005
http://www.lunar-occultations.com/iota/asteroids/astrndx.htm

Did you want me to post an official answer to your question even
though I have not been able to determine the occultation of longest
duration, or would you prefer to leave the question open in the hope
that someone else may be able to provide that fact?

---

Clarification of Question by mongolia-ga on 28 Jan 2005 03:23 PST

Pinkfreud

Please go ahead and post an official amswer.I am more than happy 
with the information given.

Many Thanks

Mongolia

Thank you very much for accepting my findings as your answer. I have
reposted the material below, with some additional links that I think
you'll find interesting.

"Alhena is also the brightest star ever observed to be occulted
(crossed over, eclipsed) by an asteroid, the minor planet 381 Myrrha
in 1991, the crossing time leading to an asteroidal diameter of 140
kilometers. The occultation revealed the fainter companion to be
almost 200 times fainter than Alhena proper and to be a main sequence
(hydrogen-fusing) G star like the Sun. From the accumulated
observations, the companion, of about one solar mass, orbits the 2.8
solar mass primary (Alhena) at an average separation of about 8.5
astronomical units (Earth-Sun distances), about the size of the orbit
of Saturn. The orbit, however, is very elliptical, taking the little
one from about as close as Earth is to the Sun to what would be close
to the orbit of Uranus."

Portraits of Stars and their Constellations
http://www.astro.uiuc.edu/~kaler/sow/alhena.html 

OBSERVED MINOR PLANET OCCULTATION EVENTS
http://www.lunar-occultations.com/iota/asteroids/obserlst.htm

The Small Bodies Node
http://pdssbn.astro.umd.edu/

IOTA Asteroidal Predictions - 1st Quarter - 2005
http://www.lunar-occultations.com/iota/asteroids/astrndx.htm

The International Occultation Timing Association 
http://lunar-occultations.com/iota/iotandx.htm

IAU: Minor Planet Center
http://cfa-www.harvard.edu/cfa/ps/mpc.html

AstDys (Asteroids - Dynamic site) 
http://hamilton.dm.unipi.it/cgi-bin/astdys/astibo

Near Earth Object Program: Orbit Diagrams
http://neo.jpl.nasa.gov/orbits/

INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE
http://hpiers.obspm.fr/

My Google search strategy:

Google Web Search: brightest asteroid OR asteroidal occultation OR occultations
://www.google.com/search?hl=en&q=brightest+asteroid+OR+asteroidal+occultation+OR+occultations

Google Web Search: duration asteroid OR asteroidal occultation OR occultations
://www.google.com/search?hl=en&q=duration+asteroid+OR+asteroidal+occultation+OR+occultations

Best regards,
pinkfreud

Regarding the duration of asteroidal occultations of stars, a lengthy
one is expected on September 12, 2008: 44.5 seconds!

http://hea.iki.rssi.ru/~denis/brightocc2.html

Wow she?s good. If I can be literal though, and ?observed? includes
non-humans, a few Mexican dinosaurs may have noticed a slightly longer
occultation in Mexico about 65 million years ago.

Best

Thank you for the five stars and the tip!

~pinkfreud