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 National Register of Historic Places listings in Central Chicago Currently there are 124 National Register of Historic Places listings in Central Chicago, out of 354 listings in the City of Chicago. Central Chicago includes 3 of the 77 well-defined community areas of Chicago: the historic business and cultural center of Chicago known as the Loop, as well as the Near North Side and the Near South Side. The combined area is bounded by Lake Michigan on the east, the Chicago River on the west, North Avenue (1600 N.) on the north, and 26th Street (2600 S.) on the south. This