Earth Planets Space, Vol. 52 (No. 10), pp. 789-794, 2000LETTER
Gaye Kizilsu and Muhammed Sahin
Istanbul Technical University (ITU), Department of Geodesy and Photogrammetry, 80626 Maslak, Istanbul, Turkey
(Received December 25, 1999; Revised August 9, 2000; Accepted August 9, 2000)
Abstract: This paper deals with the problem of properly weighting satellite observations which are non-uniform in quality. The technique, the variance component estimation method developed by Helmert, was first applied to the 1987 LAGEOS I SLR data by Sahin et al. (1992). This paper investigates the performance of the globally distributed SLR stations using the Helmert type variance component estimation. As well as LAGEOS I data, LAGEOS II data were analysed, in order to compare with the previously analysed 1987 LAGEOS I data. The LAGEOS I and II data used in this research were obtained from the NASA Crustal Dynamics Data Information System (CDDIS), which archives data acquired from stations operated by NASA and by other U.S. and international organizations. The data covers the years 1994, 1995 and 1996. The analysis is based on "full-rate" laser observations, which consist of hundreds to thousands of ranges per satellite pass. The software used is based on the SATAN package (SATellite ANalysis) developed at the Royal Greenwich Observatory in the UK.