NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Radiometric correction of atmospheric path length fluctuations in interferometric experimentsTo support very long baseline interferometric experiments, a system has been developed for estimating atmospheric water vapor path delay. The system consists of dual microwave radiometers, one operating at 20.7 GHz and the other at 31.4 GHz. The measured atmospheric brightness temperatures at these two frequencies yield the estimate of the precipitable water present in both vapor and droplets. To determine the accuracy of the system, a series of observations were undertaken, comparing the outputs of two water vapor radiometers with the phase variation observed with two connected elements of the very large array (VLA). The results show that: (1) water vapor fluctuations dominate the residual VLA phase and (2) the microwave radiometers can measure and correct these effects. The rms phase error after correction is typically 15 deg at a wavelength of 6 cm, corresponding to an uncertainty in the path delay of 0.25 cm. The residual uncertainty is consistent with the stability of the microwave radiometer but is still considerably larger than the stability of the VLA. The technique is less successful under conditions of heavy cloud.
Document ID
19840038000
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Resch, G. M.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena CA, United States)
Hogg, D. E.
(National Radio Astronomy Observatory Charlottesville, VA, United States)
Napier, P. J.
(National Radio Astronomy Observatory Socorro, NM, United States)
Date Acquired
August 12, 2013
Publication Date
February 1, 1984
Publication Information
Publication: Radio Science
Volume: 19
ISSN: 0048-6604
Subject Category
Astronomy
Accession Number
84A20787
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available