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A test of water vapor radiometer-based troposphere calibration using VLBI observations on a 21-kilometer baselineSimultaneous very long baseline interferometry (VLBI) and water vapor radiometer (WVR) measurements on a 21 km baseline showed that calibration by WVRs removed a significant fraction of the effect of tropospheric delay fluctuations for these experiments. From comparison of the residual delay variations within scans and between scans, the total tropospheric contribution t the delay residuals for each of the three 5 to 20 hour sessions was estimated as 1, 17, and 10%, with the first value being uncertain. The observed improvement in rms residual delay from WVR calibration during these three sessions was 4, 16, and 2%, respectively. The improvement is consistent with the estimated 2 to 3 mm path delay precision of current WVRs. The VLBI measurements, of natural radio sources, were conducted in April and May 1993 at Goldstone, California. Dual-frequency (2.3 and 8.4 GHz) observations were employed to remove the effects of charged particles from the data. Measurements with co-pointed WVRs, located within 50 m of the axis of each antenna, were performed to test the ability of the WVRs to calibrate line-of-sight path delays. Factors that made WVR performance assessment difficult included (1) the fact that the level of tropospheric fluctuations was smaller than is typical for Goldstone during these experiments and (2) VLBI delay variations on longer time scales (i.e., over multiple scans) contained uncalibrated instrumental effects (probably a result of slow temperature variations in the VLBI hardware) that were larger than the tropospheric effects.
Document ID
19960009474
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Linfield, R. P. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Teitelbaum, L. P. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Skjerve, L. J. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Keihm, S. J. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Walter, S. J. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Mahoney, M. J. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Treuhaft, R. N. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 6, 2013
Publication Date
August 15, 1995
Publication Information
Publication: The Telecommunications and Data Acquisition Report
Subject Category
Geophysics
Accession Number
96N16640
Funding Number(s)
PROJECT: RTOP 314-30-11-90-02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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