-The Orbit of the planet Urdu. 



Art. XII— On the Orbit of the planet Urda (167) ; by C. H. F. 



a (167). 



App. rf(167). 



Aug. 28, 14 18 21 21 58 32'22 -11 23 41-2 



" 30, 13 35 16 21 57 2'27 -11 33 23"3 



Sept. 12, 12 48 43 21 48 ]6'70 -12 31 14-2 



" 15, 12 19 28 21 46 38"63 -12 42 24'8 



It seems that the planet has not been seen anywhere else ; 

 and the orbit therefore had to be evolved from the foregoing 

 observations alone, however unequally distributed over an in- 

 terval of only eighteen days. I succeeded by computing lirst 

 a circular orbit, which served for freeing the observations from 

 aberration and parallax, and then using of the eight data the 

 four longitudes and the two extreme latitudes. The final 

 ellipse arrived at is the following: 





fl = 170° 

 i= 1° 

 cp= 18° 10' 

 /j=614-475 r 

 log a=0-5O7668. 

 Of these elements, three, 

 axis, bear a remarkable rese 

 Moreover, the element of the 

 so short an arc in our orbit, re 

 !, though 



■2" + 50 24" (t. -1876). 

 •4"_|_49-25" ( t . -1876). 

 •5"- 0-47" (t. -1876). 



ncliiiation and major 

 those of Gerda (122). 

 ', as it is derived from 



ecessarily very uncertain. 



degree, and for 



reason, with the position of the apsides, or the longitude of peri- 

 helion. Only the remaining 6th element, therefore, can decide, 

 whether the "two planets are identical. Now, for the same epoch 

 we have for Gerda L=168° 46', and as the correctness of Mr. 

 Stockwell's computations of Gerda are fully confirmed by ob- 

 servations upon this planet made at Berlin in April last, it is 

 proved that Urda is distinct from Gerda. 



The fact of two planets moving in the same plane, with the 

 same time of revolution, having also the line of apsides in com- 

 mon (our elements, if correct, show a longitude of perihelion 

 nearly 180° distant from Gerda's), but with a widely different 



