Sternberg Astronomical Institute, Lomonosov Moscow State University

by V. N. Rudenko (Sternberg Astronomical Institute, Lomonosov Moscow State University)

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

Aula Conversi

Dip. di Fisica - Edificio G. Marconi

A brief review of gravitational relativistic experiments carried out at present in Sternberg Astronomical Institute of MSU in collaboration with Russian Academy of Science is presented. First in that number  is a new “opto-acoustical gravitational gradiometer OGRAN” installed in a deep underground of Baksan Neutrino Observatory. Its goal consists in a continious monitoring of the gravitational radiation background in parallel with neutrino background registered by Baksan Neutrino Scintillator located in the same place. Such manner of operation  corresponds to the strategy of “multy-messanger astronomy” or a “collapsar searching” in the Galaxy and close enviroment. The second one consists in gravitational measurements with Radio Astron satellite. The RadioAstron space radio telescope offers a possibility for testing the gravitational redshift effect with an accuracy of better than 10^{-5}, thus, improving the result of the Gravity Probe A mission by at least an order of magnitude. However, RadioAstron's communications and frequency transfer system doesn't allow for a direct application of the nonrelativistic Doppler and tropospheric compensation scheme used in the Gravity Probe A experiment. It results in a degradation of the redshift test accuracy to approximately 1%. We discuss two approaches to overcome this difficulty and present preliminarymeasurements based on data obtained during special observing sessions scheduled for testing the new techniques.