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Re: trying for exact position of Sgr* radio source at Galactic Center

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  • mahtezcatpoc
    Thank you, Diana. Mark A. Holmes ... Printed in ... Sheridan ... center of ... determined the ... m s s ... particularly in ... (Sagittarius ... letters did
    Message 1 of 2 , Jan 14, 2006
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      Thank you, Diana.

      Mark A. Holmes

      --- In thefixedstars@yahoogroups.com, "Diana K. Rosenberg"
      <ye-stars@i...> wrote:
      >
      > The Center of the Galaxy is said to be marked by (invisible) radio
      > source Sagittarius A* - so I went googling and found this:
      >
      > http://www.isp.northwestern.edu/publications/pdf/isp1999_3.pdf
      >
      >
      > The Astrophysical Journal, 518:L33-L35, 1999 June 10
      > q 1999. The American Astronomical Society. All rights reserved.
      Printed in
      > U.S.A.
      > THE POSITION OF SAGITTARIUS A* AT THE GALACTIC CENTER
      > F. Yusef-Zadeh and D. Choate
      > Department of Physics and Astronomy, Northwestern University, 2131
      Sheridan
      > Road, Evanston, IL 60208-2900; zadeh@n...
      > and W. Cotton National Radio Astronomy Observatory, 520 Edgemont Road,
      > Charlottesville, VA 22903-2475; bcotton@n...
      > Received 1999 February 9; accepted 1999 April 7; published 1999 May 19
      > ABSTRACT
      > The absolute position of the compact radio source at the dynamical
      center of
      > the Galaxy, Sagittarius A*, was
      > known only to an accuracy of 00.2 in spite of its accurate location with
      > respect to near-IR stellar sources to within
      > 30 mas. To remedy this poor positional accuracy, we have selected 15
      > high-resolution, high-frequency VLA
      > observations of Sgr A* carried out in the last 13 years and
      determined the
      > weighted average position
      > with the average epoch 1992.4 to be at a, , or h m s s 0 d(1950) 5 17 42
      > 29.307650.0007 228759 180.484500.014
      > a, ,2297009280. 0.014, which agrees with earlier published values h
      m s s
      > d(2000) 5 17 45 40.038350.0007 06950
      > to within the 00.2 error bars of the earlier measurements. An accurate
      > absolute position of Sgr A* can be useful
      > for its identification with sources at other wavelengths,
      particularly in
      > soft and hard X-rays, with implications
      > for the models of a massive black hole at the Galactic center.
      > Subject headings: galaxies: ISM-Galaxy: center-ISM: individual
      (Sagittarius
      > A*)
      >
      > The trouble with the paragraph above is that symbols and Greek
      letters did
      > not come thru correctly;
      > so here it is with the 2000 position, which I converted to celestial
      > longitude and latitude:
      >
      > (2000) = 17h45m40.0383 + or - 0.0007 secs, -29deg00'28".069 + or -
      0.014
      >
      > which for 2000.0 is: 26Sag 51 06, Lat - 5 36 28, Decl -29 00 28,
      RA 17
      > 45 40
      >
      > I have corrected my files accordingly (I was slightly off).
      >
      > For the present (2006.1), add 5 minutes - it's now 26 Sag 56 10
      >
      > By the way the core radio source, Sagittarius A* or Sgr A* is pronounced
      > "Sagittarius A-star"
      >
      > Love, Diana
      >
      >
      > Website: http://pw1.netcom.com/~ye-stars/
      >
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