Citation
Abstract
Accurate calibration of line-of-sight delay fluctuations in the Earth’s atmosphere will be essential for future radio science experiments. In particular, the sensitivity of the Cassini gravitational wave experiment (GWE) will be limited by the performance of the calibration system of water-vapor-induced path delay. We have designed and built a high-accuracy troposphere calibration system. The primary components of this system are a pair of narrow-beam, gain-stabilized water vapor radiometers. From September 1999 to May 2000, we conducted tests at Goldstone, comparing the path delays produced by our calibration system with the line-of-sight delays measured with a radio interferometer at 8.4 GHz on a 21-km baseline. Application of our troposphere calibration measurements reduced the Allan standard deviation of the delay fluctuations on all time scales >20 s. On time scales >1000 s, the performance is within a factor of 2 of the GWE requirements. The limiting errors in this comparison appear to lie with the radio interferometry (instrument stability and geometrical modeling). Therefore, we expect further improvement with additional analysis. This article, Part I, reports on the results of the series of performancetesting experiments conducted at Goldstone from September 1999 to May 2000. A future article, Part II, will discuss the details of the instrumentation, observing strategy, data analysis procedures, and error budget.
Keywords
Details
- Volume
- 42-143
- Published
- November 15, 2000
- Pages
- 1–8
- File Size
- 826.4 KB