Densification of celestial reference frames: towards new VLBI observing strategies

International audienceBuilding celestial reference frames such as the International Celestial Reference Frame (ICRF) from Very Long Baseline Interferometry (VLBI) observations is very important for geodesy, astrometry and astrophysics. We have started a project whose objective is to develop new VLBI analysis methods and observational strategies to densify such reference frames. Our strategy takes advantage of the phase referencing VLBI technique, which allows one to detect radio sources weaker than those traditionally observed with the standard wide-angle VLBI technique used to construct the ICRF. The combination of wide-angle and phase referencing VLBI observations should provide a denser and unified reference grid comprising both strong and weak radio sources. Actual data as well as simulated data will be used to test the method