286 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



SPOT^ 



In November of 1955 Dr. Whipple mentioned to Dr. J. Allen Hynek, 

 professor of physics and astronomy at Ohio State University and 

 director of McMillin Observatory there, the strong possibility that 

 the Smithsonian would receive the satellite-tracking grant from the 

 IGY, and suggested that perhaps Dr. Hynek would be interested in 

 becoming the Observatory's associate director in charge of the pro- 

 gram. Quick to appreciate the challenge of setting up such a pro- 

 gram, and excited by the prospect of tracking satellites, Dr. Hynek 

 took leave of absence at Ohio State and came to Cambridge early 

 in January 1956. 



By late winter Whipple and Hynek had clearly outlined the means 

 by which the goal of the optical tracking program could be achieved. 

 The goal was to determine with sufficient accuracy the position and 

 time of a satellite on the celestial sphere during the evening and 

 morning twilight periods. The means were : 



1. A relatively simple super-Schmidt camera that would use a 

 continuous roll of film and two types of shutters : one a gross shutter 

 operating once during each film transport cycle, and the other a rotat- 

 ing barrel-type shutter with a period of 5 percent of the total film 

 transport cycle; the latter, which would interrupt the exposure for 

 periods of about one-hundredth of a second, would be synchronized 

 with a stroboscopic presentation of the crystal clock face that would 

 be photographed directly on the film strip. 



2. A crystal clock accurate to within 1 millisecond. 



3. A network of 10 to 12 camera stations throughout the world. 



4. Scores of teams of amateur astronomers to make preliminary 

 observations of the satellite. 



5. An orbit calculation and prediction section and a conununications 

 center at the Smithsonian Astrophysical Observatory in Cambridge. 



The task now was to make these means realities. 



THE OPTICAL TRACKING PROGRAM 



It was inevitable that Dr. Baker should be asked to design the 

 optical system of the camera. He had created the super-Schmidt 

 camera and was considered to be the world's foremost authority on 

 optical systems for astronomical cameras. In the summer of 1955 

 Dr. Whipple had gone over the various possibilities with him, and 

 together they settled tentatively on a classical Schmidt system of 

 approximately 16-inch clear aperture at f/1 and a field of view of 



8 The program is often referred to as SPOT (Smithsonian Precision Optical Tracliing). 

 Mrs. Kathryn C. Norris provided a prize for the winner of a contest to picli a suitable 

 name, and this one by Mrs. Eileen C. Cavanaugh, was chosen from among the many 

 entries. 



