The Extragalactic Radio/Optical Reference Frame

Kenneth J. Johnston, Jane L. Russell, Christian de Vegt, N. Zacharias, R. Hindsley, J. Hughes, D.L. Jauncey, J.E. Reynolds, G. Nicholson, C. Ma
1991 International Astronomical Union Colloquium  
The celestial positions of extragalactic radio sources may be determined to a precision of less than a milliarcsecond. Further, since these sources are believed to be at great distances from the galaxy, little or no proper motion is expected on scales of order a milliarcsecond. Therefore a reference frame based on the positions of carefully selected sources so that display compact radiation on scales less than a milliarcsecond will noticeably improve the precision of present celestial reference
more » ... celestial reference frames. If the radio objects making up the reference frame also emit radiation at optical wavelengths, and assuming the optical/radio radiation is coincident, the radio frame can update the optical frame to the accuracy of the individual optical positions.
doi:10.1017/s0252921100063661 fatcat:kekciza6inandcmzjadzgnfyju