During 1988 at the Munich, Vienna and Graz stations selected stars were observed for the purpose of determining difference in the longitudes. The measurements were performed with Danjon astrolabe by using the method of equal zenith distances. In the present paper the authors analyze the registration precision of 1604 star transits over a given almucantar. They estimate the variance of registration of star transits over a fictive thread as function of declination and parallactic angle before and after elimination of gross errors.

The problem of weights in the task of longitude-network adjustment has not been solved yet because the structure of the observational variances is unknown. During the adjustment of a part of the European Longitude Network in the framework of the project of including Belgrade in this network, new models of determining the components of observational variances were analyzed. These models offer a better description of the variance structure so that the weights are closer to their true values than those used up to now.

The paper presents that quasi-stationary refraction blocks have been studied, ie. know, before the advent of GPS, as well as that GPS measurement errors caused by these blocks make up one of the main components of GPS measurement variance, while errors caused by multipat do not belong to the main components of variance.

Abstract:The variance of a purely random error -"pure error" -in measuring the relative coordinates during the calculation of the orbits of binary stars, (its "unbiased estimate"), is necessary for each test used in the orbit calculation for double stars, such as the adequacy test for the orbit model, gross-error tests and the like. Since this variance is unknown, in this paper we present the robust PEROBEPE1 method which provides an unbiased variance estimate for the pure error in the coordinate measurements concerning the orbits of double stars. This estimate is independent of the model adequacy for a double-star orbit and thus can be used in any test concerning double stars.

Abstract. In high-demanding engineering applications, the latest performance improvements of the terrestrial lasers scanning (TLS) system and price decreasing trend shows the significant potential of this technology. Beside the fact that some scanners have the scanning frequency of over 1.000.000 Hz, in the engineering applications the accuracy of this survey method plays the key role. Achievement of the satisfactory accuracy of the object modelling using TLS has to be done by experiment designing. This implies the optimization process of the relevant measurements parameters and of the methodology of measurement processing through analysis of the different sources of measurement errors, instrumental precision and performance of the specific TLS, spatial configuration of the object and analysis of the models of registration and georeferencing errors. The proposed methodology of the TLS experiment design is related to the scanning of elongated objects (tunnels, corridors, pipelines, underground passages etc), which generally represent unfavourable cases in providing geodetic measurements of sufficient accuracy and reliability.