RISOTTO (Real-time Interferometry Science with Onsala Twin Telescope Observations)

Project RISOTTO (Real-time Interferometry Science with Onsala Twin Telescope Observations) aims at bringing the next-generation Very Long Baseline Interferometry (VLBI) system for geodesy and astrometry, called VGOS (VLBI Global Observing System), to its full potential.

VGOS is an international collaboration to provide highly accurate terrestrial and celestial reference frames, as well as highly accurate Earth orientation parameters.

Global geodetic reference frames have been highlights by the United Nations as crucial for the sustainable development of human society.

RISOTTO addresses the most important limiting factors for VGOS, i.e. a) radio source variability and structure, and b) instrumental stability of the VGOS telescopes. Optimized planning of VGOS sessions requires up-to-date accurate information of radio source flux density.

The automated near real-time RISOTTO pipeline routinely monitors the flux density of radio sources used in VGOS with the Onsala twin telescopes (OTT) and also continuously measures the local baseline between the OTT.

RISOTTO collects the radio source flux density information in public, open databases where the radio source catalogues are continually updated and used in planning new geodetic and astrometric VLBI sessions.

The data from the observing monitoring sessions are also used in a purely geodetic sense to routinely monitor the geodetic baseline between the OTT allowing us to characterize and model the stability of VGOS instrumentation.