44 CELESTIAL MECHANICS: LEUSCHNER 



(175) ANDROMACHE. 



Discovered by J. Watson 1 1877 October 1, but observed only Oc- 

 tober 5, 6, 16, 29. These were all the observations available until 

 rediscovery May 19, 1893. 



By an unfortunate delay the news did not reach other interested 

 observatories until two months later. The preliminary orbit, Ele- 

 ments A, by Tietjen, 2 was erroneous, partly on account of errors in 

 Watson's ringmicrometer observations. 



Watson 3 computed Elements B, and with them perturbations for 

 three years until his death in 1880. 



Bidschof 4 made an attempt to improve the orbit, Elements C, but 

 perceived the impossibility of this undertaking. 



1893, May 19, Charlios 5 at Nice discovered by photography a 

 planet, 1893 Z, and noticed the close similarity between its orbit and 

 that of (175) Andromache. He referred the case to Berberich 6 who 

 followed it out from a preliminary orbit to the best to be obtained 

 from the data in 1893 May 19- August 1, Elements D, and compared 

 his results with the observations in 1877 and with one in 1892 from a 

 photographic plate taken at Heidelberg. 



Berberich 7 next computed the extremely large perturbations by 

 Jupiter (in 1887) and Saturn, and improved the orbit by a solution 

 from four normal places in 1877, 1892, 1893, with an ephemeris for 

 the coming opposition, Elements E "this planet therefore deserves 

 peculiar attention for it will furnish an excellent means for determin- 

 ing an accurate value of the mass of the planet Jupiter." Cf. (3) 

 Juno, (4) Vesta, (13) Egeria, (24) Themis, (33) Polyhymnia, (447) 

 Valentine. 



Berberich 8 improved his elements by the following oppositions and 

 brought them forward with the special perturbations of Jupiter and 

 Saturn. The Elements F, G, H, illustrate the large changes in this 

 case of near commensurability (Hecuba group). 



This case among others impelled A. 0. Leuschner to undertake the 

 computation of the tables 9 for the Hecuba group after Bohlin's 

 method. The application of these tables to the orbit of (175) 

 Andromache was carried out by Miss S. H. Levy. Her unpublished 

 computation contains the transformation of Berberich's elements to 

 Mean Elements I, tables of the perturbations, determination of con- 

 stants, the comparison with ten oppositions between 1893 and 1907, 

 and at least squares solution which led to the Mean Elements J. The 

 representation of observations in 1914 was O m .4 in a and + 1' in 8. 



The comparison between theory and observation has been discussed 

 by A. 0. Leuschner. 10 



