28 



ASTRONOMICAL OBSERVATIONS 



From tlie Greenwich Nautical Almanac, as corrected by the Greenwich observations : — . 



At immersion, a <L . . .3^ oO" 51M3 

 At emersion ( C) . . . 3 32 46.19 

 (M) . . . B 32 4T.50 

 (Correction to Nautical Almanac — 0^.35.) 

 At immersion, « (L . . . +17° 51' 04".3 

 At emersion (C) . . . 18 00 24.4 

 (B) . . . 18 00 2T.9 

 (Correction to Nautical Almanac — 5".5.) 

 At immersion, horizontal parallax C 54' 34".4 

 At emersion ( C) . . . .54 33.4 

 {R) . . . . 54 33.4 

 (Correction +1".0 according to Adams.) 

 At immersion, semidiameter <L . .14' 52".5 

 At emersion (C) . . . .14 52.3 

 {R) . . . . 14 52.3 

 (Correction — l".l according to Oudeman.) 



At immersion, o >2 . . . S'' 32™ 30'. 91 

 At emersion (0) . . . 3 32 31.09 

 (iJ) . . . 3 32 31.09 

 (Correction to Nautical Almanac +0^25.) 

 At immersion, « >z . , . +17°05'46".4 

 At emersion (C) . . . 17 05 47.7 

 {R) . . . 17 05 47.7 

 (Correction to Nautical Almanac — 8". G.) 



Horizontal parallax \ 

 Semidiameter 'h 



l."0 

 3.4+ 1.2 



Greenwich mean time of 6 5'' 5'' 15™ 57^5 



Immersion {R). 



Emersion (C). 



Emersion (7J). 



Cs horizontal paral. at Van Rensselaer 

 Relative parallax 7t . . . . 

 a. — s ....... 



a' — a=jp ...... 



&'—& = q 



Augmented semidiameter C . 



—258° 22 

 + 11 



— 51 



54' 23".9 

 54 22.9 

 16.5 

 06.42 

 36.75 

 896.1 



—272° 25 

 + 11 



54' 22".9 

 54 21.9 



15 



20.72 

 50 46.80 

 896.6 



—272° 30 

 + 11 



— 50 



54' 22".9 

 54 21.9 

 24 



20.68 

 46.56 

 896.6 



For the construction of the diagram the following quantities were used: 



Apparent a C at immersion 

 Relative app. dif. in AR (red.) 

 " " in declination 



31™36M6 

 — 13'05".l 

 — 6 18.9 



Geocentric elements of Saturn's ring : 



;; = - 2° 24' 

 ffl= 42.1 



b= —17.1 



At emersion (C) S"" 33™ 32 M 7 

 + 14' 35".5 

 + 3 49.9 



a'= 28.0 



6'=— 11.5 



Southern surface visible. 



(R) 3^ 33™ 32". 88 

 + 14' 45".7 

 + 3 53.6 



