Abstract The accuracy of geodetic Very Long Baseline Interferometry (VLBI) is affected by water vapour in the atmosphere terms variations signal propagation delay at different stations. This “wet” may be estimated directly from VLBI data, as well independent instruments, such collocated microwave radiometers. Rather than having stand-alone radiometers we have, through simulations, evaluated pos...

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...

Cepheids are the primary distance indicators for extragalactic astronomy and therefore are of very high astrophysical interest. Unfortunately, they are rare stars, situated very far from Earth. Though they are supergiants, their typical angular diameter is only a few milliarcseconds, making them very challenging targets even for long-baseline interferometers. We report observations that were ob...

Abstract Active galactic nuclei (AGN) have been observed as far redshift $z \sim 7$ . They are crucial in investigating the early Universe well growth of supermassive black holes at their centres. Radio-loud AGN with jets seen a small viewing angle called blazars and show relativistic boosting emission. Thus, apparently brighter easier to detect high-redshift Universe. DES J014132.4–542749.9 is...