150 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



eral solutions have been obtained for the representation of the field 

 of gravity. Tliese solutions are in reasonable agreement with results 

 obtained from the analysis of surface gravity data. 



Other analyses of the geopotential are continuing. In Japan Dr. 

 Kozai is at present seeking to establish whether the coefficients in the 

 expansion of the earth's potential have seasonal variations. 



Using the representation of the geoid derived by Izsak, Kozai, and 

 their colleagues, Chi-Yuen Wang has found a strong correlation 

 between the distribution of heat flow and the undulations of the 

 geoid.^ It is reasonable to say at this time that the ups and downs 

 of the geoid may indicate cold and hot regions under the crust. 



Two approaches to the determination of more accurate station coor- 

 dinates are being pursued at the Observatory. One of these recog- 

 nizes that the deviations between values observed from a station 

 and values predicted from theoretical calculations depend on errors in 

 the presumed station coordinates. Those coordinates that produce 

 minimum deviations are adopted as improved coordinates. Mr. Izsak 

 and Dr. George Veis are now effecting this procedure simultaneously 

 with improvements in the geopotential coefficients.^ 



The second approach is purely geometrical. If two stations simul- 

 taneously observe a satellite, it is possible to calculate the direction 

 cosines of the line joining the stations. During the past year a deter- 

 mined effort by the Baker-Nunn stations produced a number of simul- 

 taneous observations. Some of these were photographs of the light 

 flashes from the ANNA geodetic satellite. Although we do not yet 

 have so many simultaneous observations as we would desire, analy- 

 sis by Dr. Veis, Jan Rolff, and Antanas Girnius have given reasonable 

 values in satisfactory agreement with those of the other approach. 



For computation of datum shifts of large (continental) geodetic 

 systems,^ Dr. Walter Kolinlein has developed special ellipsoidal trans- 

 formations. These transformations are required to adjust the large 

 system so that their relative configurations are in accord with the 

 determined station locations. 



For full exploitation of these geodetic capabilities, a more extensive 

 network than the 12 Baker-Nunn stations is desirable. An inexpen- 

 sive satellite-tracking camera able to photograph many of the brighter 

 satellites has been designed and fabricated under the direction of 

 Dr. Veis and Robert W. Martin. This prototype camera is in experi- 

 mental operation in Athens, Greece. 



Not only the orbit of an artificial satellite but also its motion about 

 its center of mass is affected by its environment. A theory developed 

 by Dr. Giuseppe Colombo has been confinned with the observation 



Se« footnotes on p. 164. 



