Gedeonov Method

a method for determining the corrections for clocks under expedition conditions, proposed by D. D. Gedeonov in 1884. Observations are carried out with a portable theodolite used as a transit instrument, for which purpose it has a superposed level for controlling the inclination of the horizontal axis. The eyepiece section of the instrument contains a network of vertical hairs. Four stars are observed at small zenith distances. In order for the collimation error to enter the equations with different signs, observations are made with the instrument at two different positions. Two stars are observed at each position, one south and one north of the zenith. The observer fixes the time at which the stars pass each of the vertical hairs of the network and records the readings of the levels. The observed data are used for determining the chronometer correction and the instrument errors. The Gedeonov method has a number of advantages for observations at high geographic latitudes and is used in geodetic work for determining class III and class IV astronomical points.