THE ASTRONOMICAL JOURNAL    VOLUME 110, NUMBER 2, PAGE 880          AUGUST 1995

                            A RADIO REFERENCE FRAME

                      KENNETH J. JOHNSTON AND ALAN L. FEY

         Remote Sensing Division, Code 7200, U.S. Naval Research Lab,
               Washington, DC 20375 and U.S. Naval Observatory,
              3450 Massachusetts Avenue NW, Washington, DC 20392
       Electronic mail: kjj@astro.usno.navy.mil, afey@alf.usno.navy.mil

                               NORBERT ZACHARIAS

         Universities Space Research Association, Washington, DC 20024

                                JANE L. RUSSELL

            Applied Research Corporation, Landover, Maryland 20785

                                   CHOPO MA

       Goddard Space Flight Center, Code 921, Greenbelt, Maryland 20771

                               CHRISTIAN DE VEGT

  Hamburger Sternwarte, Universitat Hamburg, Gojenbergsweg, Hamburg, Germany

                     JOHN E. REYNOLDS AND DAVID L. JAUNCEY

   Australia Telescope National Facility, CSIRO, Epping, NSW 2121, Australia

  BRENT A. ARCHINAL, MERRI SUE CARTER, THOMAS E. CORBIN, T. MARSHALL EUBANKS,
          DAVID R. FLORKOWSKI, DAVID M. HALL, AND DENNIS D. McCARTHY

  U.S. Naval Observatory, 3450 Massachusetts Avenue NW, Washington, DC 20392

                     PETER M. McCULLOCH AND EDWARD A. KING

           University of Tasmania, Hobart, Tasmania 7001, Australia

                                GEORGE NICOLSON

                  Hartebeesthoek Radio Astronomy Observatory,
                    P.O. Box 443, Krugersdorp, South Africa

                               DAVID B. SHAFFER

       Radiometrics Inc., 1742 Saddleback Court, Henderson, Nevada 89014


                                   ABSTRACT

    A catalogue is presented based on the radio positions of 436
    extragalactic sources distributed over the entire sky.  The positional
    accuracy of the sources is better than 3 milliarcsec (mas) in both
    coordinates, with the majority of the sources having errors better than
    1 mas.  This catalogue is based upon a general solution of all
    applicable dual frequency 2.3 and 8.4 GHz Mark-III VLBI data available
    through the end of 1993 consisting of 1,015,292 pairs of group delay
    and phase delay rate observations.  Details and positions are also
    given for an additional 124 objects that either need further
    observation or are currently unsuitable for the definition of a
    reference frame.  The final orientation of the catalogue has been
    obtained by a rotation of the positions into the system of the
    International Earth Rotation Service and is consistent with the FK5
    J2000.0 optical system, within the limits of the link accuracy.