70 CELESTIAL MECHANICS: LEUSCHNER 



(884) PRIAMUS, 1917 CQ. 



Discovered by Wolf 1 at Heidelberg on September 22, 1917. 



Wilkens outlines 2 his preliminary investigation regarding the 

 motion of this fifth member of the Trojan group. For this purpose 

 he utilizes preliminary Elements A, by Berberich. The libration 

 point is 60 behind Jupiter and the planet oscillates about this point 

 in approximately 150 years. He states that /* varies between 

 294".27 and 303".99. He also points out that his succeeding work 

 will show that Priamus and Patroclus are diametrically opposite in 

 the small libration ellipse. 



Klose applies 3 Wilkens' method 4 for taking into account the prin- 

 cipal perturbations of Jupiter, to Priamus. In this method the prin- 

 cipal perturbations by Jupiter are accounted for by centering in 

 the Sun the mass of the Sun-Jupiter system. For this study 

 Klose utilizes Berberich 's Elements A, bringing them up to mean 

 equinox 1925.0, Elements B, and compares the coordinates computed 

 from Elements B plus special perturbations with those computed from 

 Elements C, which were derived by Wilkens' method. The differ- 

 ence in the representation by the two sets of elements for observa- 

 tions from 1917 October 14 to 1918 December 28, did not exceed O s .5 

 in right ascension and 2" in declination. Klose concludes that Wil- 

 kens' method is applicable beyond this short period for immediate 

 Ephemeris purposes. 



As an example of his method 5 of integrating the differential equa- 

 tions for the perturbations in the coordinates for planets of the 

 Jupiter group, Wilkens 6 gives a numerical application for Priamus. 

 His results are similar to those of Klose. Klose 7 publishes a further 

 comparison between the usual method of special perturbations due 

 to Jupiter and Wilkens' method. For this purpose he compares 

 results gotten from Elements B and a new set of Elements D, 

 derived by Wilkens' method. He then brings up Elements B with 

 perturbations due to Jupiter up to epoch 1918 (Elements E), and 

 Elements D are brought forward to epoch 1918 by Wilkens' method. 

 An ephemeris is published for the opposition 1919 for which the per- 

 turbations of Saturn are also taken into account. 



In an article on "Bemerkenswerte Eigenschaften der Bahnen der 

 Planeten der Jupitergruppe," Wilkens 8 points out that the ascending 

 nodes of the six Trojan planets lie with one exception, (Patroclus), in 

 the same quadrant. He also forms a mean value of the ascending 

 nodes from certain planets of the group and compares the individual 

 values with these mean values. He also refers to his article 9 regarding 

 the time of maximum and minimum for the mean motion of Priamus 



