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Re: [LX200GPS] Re: Near Earth Asteroid Pass Monday-Tuesday

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  • John Mahony
    ... It looks like more observations came in and the MPC has revised its estimate upward from .0003 to .00055 AU, or a bit over 50,000 miles. It s a good thing
    Message 1 of 6 , Feb 28, 2009
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      ----- Original Message ----

      > From: autostaretx <rseymour@...>
      >
      > A little masked by Dr. Clay's number, but 0.0003 AU works out
      > to about 28,000 miles. And other sites refer to it in Lunar
      > Distances (1 LD is about 240,000 miles) as 0.2 LD.
      > So that's about 48,000 miles (whew).

      It looks like more observations came in and the MPC has revised its estimate upward from .0003 to .00055 AU, or a bit over 50,000 miles. It's a good thing the revision didn't go the other way or there might be one helluva splash in the South Pacific tomorrow night. The revision was by .00055 - .0003 = .00025 AU, and _subtracting_ that "correction" from .0003 would have left only .00005 AU = 4600 miles. And that's measured from the _center_ of the earth, so it would clear the surface by only about 600 miles, which is _way_ within the margin of error of the estimates at this point.

      To put the size into perspective, this object is about the size of the one that caused the Tunguska blast in Siberia in the early 20th century, or the one that created the Barringer meteor crater in Arizona. I wonder how the tidal wave it could produce would compare to the one near the same area at Christmas a few years ago.

      -John



      > > ----- Original Message ----
      > > > From: P. Clay Sherrod
      > > > To: P. Clay Sherrod
      > > > Sent: Saturday, February 28, 2009 1:00:38 PM
      > > > Subject: [LX200GPS] Near Earth Asteroid Pass Monday-Tuesday
      > > >
      > > > An exciting very close pass of a Near Earth Asteroid for observers
      > in the
      > > > northern
      > > > hemisphere awaits Monday and Tuesday nights; NEO 2009 DD45 will
      > skim within
      > > > 0.0003 AU of
      > > > the earth during the early evening hours of March 1 (2nd UT) and
      > will attain a
      > > > brightness
      > > > of at least mag. 10.8, perhaps brighter.
      > > >
      > > > This object is moving incredibly fast, so charts and preparations
      > will be
      > > > necessary to
      > > > even keep up with it telescopically as it moves rapidly north and
      > east each
      > > > hour.
      > > >
      > > > For full details and ephemeris information, click:
      > > > http://www.cfa.harvard.edu/mpec/K09/K09D80.html
      > > >
      > > > For details on the exact elements to enter into any PC or GO TO
      > program, use the
      > > > MPC
      > > > Ephemeris service at:
      > > > http://www.cfa.harvard.edu/iau/MPEph/MPEph.html
      > > >
      > > > This is an incredible opportunity to witness a very, very close
      > pass of a
      > > > dangerous NEO
      > > > toward Earth.
      > > >
      > > > Have fun!
      > > >
      > > > Dr. Clay
      > > > _____
      > > > Arkansas Sky Observatories
      > > > MPC H45 - Petit Jean Mountain South
      > > > MPC H41 - Petit Jean Mountain
      > > > MPC H43 - Conway West
      > > > http://www.arksky.org/
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