If successful, this will be the first realization of a large optical astrometry catalog directly anchored to the ICRF. The grid catalog includes ~5000 extragalactic radio sources with VLBI-detected positions accurate to 1 mas or better, which are used as hard constraints to the astrometric unknowns in the global least-squares adjustment. Our approach is to solve a huge system of linear equations for a carefully selected set of ~1 million grid objects including the astrometric unknowns (positions, proper motions and parallaxes) and FoV calibration parameters. The absence of proper motions in 2MASS results in significant sky-correlated errors up to 30 - 50 mas. Sometimesbut not alwaysthey develop distinctive tails of gas and dust. When comets are close to the Sun, they warm up. It presently discovers over half of the larger Near Earth Objects (diameter > 140. The 2MASS positions were used as reference for field of view (FoV) and detector calibration procedures. Their orbits around the Sun carry them from the far, outer parts of the solar system to the inner solar system, where they can become visible from Earth. Pan-STARRS1 is the worlds leading Near Earth Object discovery telescope. The current approach used in the data reduction pipeline is strictly differential. The 3PI survey performed by the PS1 telescope is well suited for a global astrometric solution. A small collaboration of USNO and IfA astronomers is working on an improved astrometric solution for the data collected by the Pan-STARRS project.
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