160 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



Observations of magnetic fields and velocity fields in the solar 

 granulation were carried out by Dr. R. W. Noyes at the McMath Solar 

 Telescope at Kitt Peak National Observatory in Tucson during June 

 1963. The data are now being analyzed. 



Dr. Fireman, Dr. Tilles, and Mr. DeFelice have continued measure- 

 ments of tritium concentrations in recovered satellites. Such measure- 

 ments made during the past year have pertained to a period of relative 

 solar quiescence. The apparent upper limit for trapped tritium 

 abundance was much lower in 1962 than it was following the No- 

 vember 1960 solar flares. The measurements to date suggest that these 

 large flares injected tritium into the trapped radiation belts with 

 apparent lifetimes of months. This first evidence of direct solar in- 

 jection of positive Van Allen particles is under continuing critical 

 examination. 



It is clear that particles and electromagnetic radiation from the 

 sun produce many such diverse phenomena in the solar system. Their 

 interaction with the earth's atmosphere results in large density varia- 

 tions which are manifest in variations of satellite orbits. These 

 radiations also influence cometary activity. The interpretation of 

 these far-reaching interrelated phenomena is particularly challenging 

 because of its very scope. The present period of minimum solar 

 activity has many advantages for research on these matters. The 

 Observatory is vigorously pursuing these topics, which will be in- 

 cluded in the U.S. program for the Year of the Quiet Sun. 



Stellar ohservations. — The Observatory's astrophysical interests ex- 

 tend beyond the investigations of the solar system. Using various 

 instruments, SAO acquires and analyzes observational data on stars, 

 galaxies, and interstellar matter in all forms. 



Like solar observations, stellar observations stand to benefit greatly 

 from the advent of orbiting observatories. The Observatory is privi- 

 leged to have responsibility for Project Celescope,^^ one of the two 

 prime experiments on the first Orbiting Astronomical Observatory. 

 Dr. Wliipple is project director, and Dr. Robert J. Davis is project 

 scientist. Dr. Grossi has supervised electronic aspects of the project. 



The primary goal of Project Celescope is to obtain ultraviolet star 

 catalogs in each of four colors between 1,000 and 3,000 A. The wave- 

 length range requires that this observing program be carried out above 

 the earth's atmosphere. Four separate telescopes equipped with 

 ultraviolet-sensitive television photometers will be used. The present 

 phase of the program is concerned primarily with procurement of 

 the necessary equipment. The experiment has required the develop- 

 ment of the following pioneering instrumentation and techniques: 



See footnotes on p. 164. 



