340 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1964 



In the summer of 1958, Dr. Veis, assisted by Charles Moore, a 

 student at M.I.T., modified the program so as to omit its geodetic 

 aspects. By the end of the year, they had a working program, al- 

 though it still needed a good deal of effort to smooth out difficulties. 

 In the spring of 1959, Dr. Veis presented a paper on this technique, 

 at the N.A.S.A. conference on Orbit and Space Trajectory Determina- 

 tion in Washington ; the program itself went into routine operation 

 at about the same time. 



This differential orbit improvement program, with the modifications 

 that have been made since its inception, has proved to be the work- 

 horse of the computing effort of the Observatory. In fact, it 

 has so far exceeded its original purpose that it continues in the 

 mid-1960's to be the best program for correcting orbits and has been 

 used for the highly precise geodetic work of Imre Izsak and others, 

 as well as for further refinement of measurements of upper atmos- 

 pheric densities and temperatures. 



Various other programs, many of them higlily specialized, were 

 also undertaken by the computations group of the Observatory in 

 this period. Two merit special attention, since they were to have 

 important bearing on the development of the satellite-tracking project 

 after it came under the auspices of the National Aeronautics and 

 Space Administration. 



Mr. Slowey began a study of observing techniques and orbit deter- 

 mination methods relating to long-arc satellite transits. A primary 

 purpose of long-arc observations would be to make simultaneous sight- 

 ings of a satellite from two or more Baker-Nunn camera stations ; the 

 resultant data could be used to determine more exactly the geodetic 

 positions of the stations themselves. 



Dr. Veis initiated a long-range program of establishing a star 

 catalog in punchcard format. This project would in time result in 

 the preparation of the famous SAO catalog giving the positions and 

 other data on more than a quarter of a million stars. 



While these and other programs were being developed, the com- 

 putations group carried on its day-to-day activities with increasing 

 efficiency and success. In the first quarter of 1958 they processed 

 approximately 2,500 satellite observations, including some from Mini- 

 track. This number steadily grew during the months that followed, 

 so that from April to June of 1959, more than 12,000 observations 

 were processed. The group achieved a similarly spectacular increase 

 in the number of predictions of satellite transits sent to the 12 Baker- 

 Nunn stations. From the meager beginnings late in 1957, the figure 

 rose to 1,700 for the last 3 months of 1958, and to 6,700 for April 

 through June of 1959. 



