Radio optical reference frame. 6: Additional source positions in the northern hemisphere

Abstract

view Abstract Citations (9) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radio Optical Reference Frame. VI. Additional Source Positions in the Northern Hemisphere Fey, A. L. ; Russell, J. L. ; de Vegt, C. ; Zacharias, N. ; Johnston, K. J. ; Ma, C. ; Hall, D. M. ; Holdenried, E. R. Abstract Radio and optical positions for northern hemisphere extragalactic sources are reported. Milliarcsecond (mas) accurate radio positions of 106 sources north of -2^deg^ declination are derived from Mark III VLBI observations taken during ten experiments from 1990 January through 1990 October. The results presented supplement an ongoing project to define and maintain an all-sky radio/optical reference frame of 400 or more extragalactic sources with mas accurate radio and optical positions. Radio positions for 34 new sources are presented along with improved radio positions for 72 sources already in the reference frame catalogue. An additional nine sources have been determined to be unsuitable reference frame objects. Radio observations of nine calibration sources tie the new positions to the existing catalogue. The radio positions of the new sources have formal mean errors of ~0.7 mas in right ascension and ~1.0 mas in declination. Sources for which we report improved radio positions now have formal mean errors of ~0.5 mas in both coordinates, an improvement in some cases by as much as 75%. Positions in the FK5 system have also been obtained for the optical counterparts of an additional five northern hemisphere radio sources using prime focus plates from the Kitt Peak National Observatory's 4 m telescope and a Kitchey-Chretien focus plate from the Calar Alto 2.2 m telescope. The optical positions have internal accuracies of ~0.03" and differ from the radio positions by 0.07" on the average. Publication: The Astronomical Journal Pub Date: January 1994 DOI: 10.1086/116862 Bibcode: 1994AJ....107..385F Keywords: Astronomical Coordinates; Extragalactic Radio Sources; Position (Location); Reference Stars; Astrometry; Northern Sky; Radio Astronomy; Sky Surveys (Astronomy); Very Long Base Interferometry; Astrophysics; REFERENCE SYSTEMS full text sources ADS | data products SIMBAD (124) NED (106)