APPENDIX 8 

 REPORT ON THE ASTROPHYSICAL OBSERVATORY 



Sm : I have the honor to submit the following report on the activi- 

 ties of the Astrophysical Observatory for the fiscal year ended June 

 30,1942: 



WORK AT WASHINGTON 

 PUBLICATION OF VOLUME 6 OF THE ANNALS 



The outstanding event was the completion and publication of 

 volume 6 of the Annals of the Observatory. The volume begins with 

 extracts from these reports continuing the annals of the Observatory 

 operations from 1931 to 1940. Next, the principal research on the 

 variation of the sun's radiation is minutely described, with illustra- 

 tive graphical and tabular matter relating to every feature. Then 

 follow 78 quarto tabular pages giving in detail daily results of 

 observation of the solar constant of radiation (i. e., the intensity of 

 the sun's rays as they exist at mean solar distance outside the earth's 

 atmosphere). This table covers all observations over the interval 

 from 1923 to 1939 at Montezuma, Chile; Table Mountain, Calif.; and 

 Mount St. Katherine, Egypt. The results are given in 12 columns 

 for each day, covering not only the final results at each station, but 

 the more important observations leading up to them. For some 

 individual dates as many as 12 lines are required. Each page of the 

 Annals includes 3 such groups of columns or 36 in all, and each page 

 has approximately 80 lines. The enormous task of preparing this 

 table has been mentioned repeatedly in preceding reports. 



Then follows a chapter on the derived results and conclusions based 

 on this great tabular compilation, and including related additional 

 information for the years 1920 to 1923, derived from volume 5 of the 

 Annals. 



As regards accuracy, the probable accidental error of a single day's 

 determination of the solar constant from observations at the stations 

 is one-sixth of 1 percent, and for 10-day and monthly means, it is 

 one-ninth and one-twentieth of 1 percent, respectively. 



The variation of the sun, as our life-supporting star, is clearly 

 indicated and between extreme ranges up to about 3 percent for the 

 interval 1920 to 1939. It is verified not only by comparisons of our 



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