Astronomical Data Center

ADCADC/CDS Standard Document for Catalog:
/external/radio/E8003/

The ADC has expanded its resources in order to better serve our users, we have developed a new category called "external" to complement our catalogs and journal table directories. You can access the data set described here through the URL:
http://rorf.usno.navy.mil/rrfid.html.

The following is an abbreviated "ReadMe" document that describes this external data set.
E/VIII/3   USNO Radio Reference Frame Image Database                (Fey+ 1998)
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USNO Radio Reference Frame Image Database (RRFID)         
   Fey A.L, Kingham K.A., Gaume R.A. 
   <U.S. Naval Observatory (1998)> 
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ADC_Keywords: Radio sources; VLBI; Positional data; External catalog 

Location: http://rorf.usno.navy.mil/rrfid.html
             
Description:   
    The U.S. Naval Observatory (USNO) Radio Reference Frame Image Database is 
    a collection of over 1000 VLBI 'snapshot' images of over 300 compact 
    extragalactic radio sources (quasars, BL Lacs, etc.). Images are obtained 
    from VLBA observations and/or from geodetic/astrometric observations at 
    frequencies of 2 GHz, 8 GHz, and 15 GHz. These data are the result of an 
    ongoing program to image International Celestial Reference Frame (ICRF) 
    sources on a regular basis and are being used by us primarily to monitor 
    sources for variability and/or structural changes so that the sources can 
    be evaluated for continued suitability as reference frame objects. However, 
    the data are available for scientific use by anyone. PostScript format 
    plots of images and/or visibility data are available directly from the 
    World Wide Web site at http://rorf.usno.navy.mil/rrfid.html. Images 
    and/or visibility data in FITS format can be obtained upon request. 
    
    VLBA Images -- `snapshot' images made using the National Radio Astronomy 
    Observatory (NRAO) Very Long Baseline Array (VLBA) telescope. Images
    using the VLBA together with several geodetic antennas are also available 
    for some sources. These 'VLBA+' images provide enhanced uv-plane coverage 
    and up to twice the resolution of the VLBA alone. Available items include 
    contour plots and visibility plots in PostScript format. Images and/or 
    visibility data can also be obtained in FITS format upon request.

    Geodetic VLBI Images -- `snapshot' images made using geodetic and/or 
    astrometric Very Long Baseline Interferometry (VLBI) observations. 
    Available items include contour plots in PostScript format. 

References:
    Fey A.L., Clegg A.W., Fomalont E.B., "VLBA Observations of Radio Reference 
     Frame Sources I.," ApJS 105, No. 2, 299
     =1996ApJS..105..299F

    Fey A.L., Charlot P. "VLBA Observations of Radio Reference Frame Sources II.    Astrometric Suitability Based on Observed Structure," ApJS 111, No. 1, 95   
     =1997ApJS..111...95F
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(End)                        James E. Gass      [ADC/SSDOO]          11-May-1998
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