Geocentric Coordinate Time Geocentric Coordinate Time Geocentric Coordinate Time (TCG - Temps-coordonnée géocentrique) is a coordinate time standard intended to be used as the independent variable of time for all calculations pertaining to precession, nutation, the Moon, and artificial satellites of the Earth. It is equivalent to the proper time experienced by a clock at rest in a coordinate frame co-moving with the center of the Earth: that is, a clock that performs exactly the same movements as the Earth but is outside the Earth's gravity well. It is therefore not influenced by the gravitational time dilation caused by the Earth. TCG was
National Register of Historic Places listings in Central Chicago Chicago architecture. Architect Louis Sullivan's work is represented by the Carson, Pirie, Scott and Company Building, and Auditorium Building. Though Frank Lloyd Wright worked downtown early in his career as an assistant to Sullivan - including work on the James Charnley House - his own work in the central city is represented only by a renovation of the lobby of Daniel Burnham's and John Wellborn Root's Rookery Building. At least three sites relate to the city's role in nationwide retailing. Included also are several religious buildings, six hotels, and four theaters. National Register of Historic Places listings in Central Chicago