We discuss the impact of the results from the recent Hipparcos astrometric satellite on distance estimates of galactic globular clusters. Recalibrating the clusters not only implies a relatively small change in the distance to the Large Magellanic Cloud, and hence a rescaling of several estimates of the Hubble constant, but also leads to significantly younger cluster ages. Although the data are...

We present a new technique to extract the cosmological information from high-redshift supernova data in the presence of calibration errors and extinction due to dust. While in the traditional technique the distance modulus of each supernova is determined separately, in our approach we determine all distance moduli at once, in a process that achieves a significant degree of self-calibration. The...

IEEE Network • September/October 1998 he global information infrastructure (GII) of the United States has included satellite asynchronous transfer mode (SATM) as part of the communications infrastructure to support global mobile communications, information transport and access. The Telecommunications Industry Association (TIA) has recently formed an SATM group to study the various technical iss...

Galaxy-galaxy lensing is rapidly becoming one of the most promising means to accurately measure the average relation between galaxy properties and halo mass. In order to obtain a signal of sufficient signal-to-noise, one needs to stack many lens galaxies according to their property of interest, such as luminosity or stellar mass. Since such a stack consists of both central and satellite galaxie...

This paper describes the evaluation of precise point positioning (PPP) using the Quasi-Zenith Satellite System (QZSS) L-band Experiment (LEX) signal. The first QZSS, the Japanese regional satellite navigation system, was launched from Japan in September 2010. QZSS transmits augmentation signals to enhance the global navigation satellite system (GNSS) positioning accuracy. One of the QZSS augmen...

In this paper a practical method for tropospheric effects on GPS derived coordinates in absolute mode is presented. GPS observations at the permanent GPS stations can be used as source of information for the modeling. The developed model is a time-dependent model and as such differs from usual tropospheric models, which are based on atmospheric parameters, i.e. temperature, pressure and humidit...

Satellite data have been used for temperature modeling both in urban areas and water. This paperstudies viability of ASTER satellite images that provide high spatial and spectral resolution to model watersurface temperature, as a fundamental water quality parameter. This study is focused on Dez dam reservoirresiding in Khuzestan province, south west of Iran. After the image corrections required...

In the near future space activities, the in-orbit servicing capability which means transportation of logistics, maintenance of spacecraft and assist of scientific activities such as space experiments are highly required. These work will be partly conducted by astronauts and manned spacecraft. However, most of these works should be done by unmanned spacecraft and robots from the safety and cost ...