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Fwd: Large TNO occultation possible in Americas Feb. 10/11

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  • Richard Kowalski
    ... [Non-text portions of this message have been removed]
    Message 1 of 2 , Feb 5, 2008
      Begin forwarded message:

      > From: David Dunham <dunham@...>
      > Date: February 5, 2008 11:45:17 PM MST
      > Subject: Large TNO occultation possible in Americas Feb. 10/11
      >
      > Observers throughout the Americas, and even westernmost Europe,
      > have a chance to observe an occultation of an 11.3-mag. star in
      > Gemini by the large (maybe even 1000 km) distant trans-Neptunian
      > object (TNO) 20000 Varuna on Sunday night, Feb. 10/11. Observers in
      > South America are especially encouraged to try to observe this
      > event since they have the highest probability for an occultation.
      > The nominal path misses the Earth to the south, but the real
      > uncertainties in the prediction are hard to access, as Steve
      > Preston notes, so there is a chance for an event even in North
      > America. Occultations of stars this bright by such large TNO's
      > are quite rare, and so far, none beyond Pluto/Charon have been
      > observed. Even if an occultation by Varuna doesn't occur, there
      > could be an occultation by a possible satellite of Varuna.
      >
      > The closest approach time is 4:26 UT of Feb. 11 UT in South
      > America, and about 4:30 UT in North America. The formal
      > 1-sigma uncertainty in the time is about 5 min., but you should
      > be prepared for at least a 3-sigma event; I would recommend
      > monitoring/recording the star for at least 20 min. before and
      > after the predicted time for your station. If an occultation
      > occurs, there will be a 9-mag. drop lasting about 43 seconds
      > for a central event. The star to be occulted is TYC 1913-00670-1
      > at J2000 RA 7h 18m 50.1s, Dec +25 deg. 43' 19", 2.5 deg. s.s.w.
      > of 5th-mag. iota Geminorum and 1.3 deg. w.n.w. of 6th-mag.
      > 57 Geminorum. Detailed finder charts of different scales are
      > on Steve Preston's Web site for the event at
      > http://www.asteroidoccultation.com/2008_02/0211_20000_16750.htm ;
      > it also has a view of the Earth as seen from Varuna that can
      > be used to estimate your time of closest approach, and altitude
      > above your horizon.
      >
      > Please spread word of this event; good luck with your observation!
      >
      > David Dunham, IOTA
      >
      >




      [Non-text portions of this message have been removed]
    • Brian Skiff
      ... This star is somewhat fainter than this. The TASS MkIV data shows V = 11.94 +/- 0.04. The Carlsberg meridian circle catalogue gives Sloan r = 11.74.
      Message 2 of 2 , Feb 5, 2008
        >> ...occultation of an 11.3-mag. star...

        This star is somewhat fainter than this. The TASS MkIV data shows
        V = 11.94 +/- 0.04. The Carlsberg meridian circle catalogue gives
        Sloan r' = 11.74. The ASAS-3 database shows mean V = 11.91 +/- 0.05,
        consistent with the TASS mean value (n=15 observations for TASS versus
        n=11 for ASAS-3).


        \Brian
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