of Stars to the ninth magnitude. 25 



Art. Y.— Abstract of the Programme for the Observation of Stars 

 to the Ninth Magnitude, undertaken hy the German Astronomi- 

 cal Society.* 



The Astronomical Society undertakes the ( 

 complete catalogue for tlie northern heavens of the stars of the 

 first nine magnitudes, upon the basis of the Bonn Durchmuste- 

 ruag. The region to be observed lies between —2° and +80° 

 of declination. The region around the pole is not iiichided. as 

 the labors of Carrington, the Kasan and the Hamburg obsri\ a- 

 tories render a repetition of this work supei-fluous on the pari 

 of the Society. The work will be distributed as fol5j>\\'^ '■ Ka- 

 san 80° to 75° ; Dorpat 75° to 70° ; Christiania 70° to (55^ ; 

 Helsingfors 65° to 55° ; Cambridge, U. S., 55° to 50° ; Bonn 

 50° to 40°; Chicago 40° to 85°; Leipzig 35" to 30°; Cam- 

 bridge, Eng., 30° to 25° ; Berlin 25° to 15° ; Leipzig 15° to 10° ; 

 Mannheim 10° to 4° ; Neuchatel 4° to 1° ; Palenno + 1° to -2°. 



The limits of these zones refer to the equinox of 1855-0, 

 which is that of the Durchmusterung. For purposes of ^com- 

 parison, the limits above given will be exceeded 5' to 10', and 

 in very northerly regions even more. 



In particular "the stars to be observed are as follows: All 

 stars of the D. M. within the prescribed hmits having a mag- 

 nitude of 9-0 or brighter; all stars fainter, which also occur m 

 the Histoire Celeste (marked in the D. M., L), or m the Ko- 

 nigsberg zones (marked K), or in the Bonn zones (marked A) ; 

 a part of these latter, which have been recently determmed at 

 Bonn, (marked B). A comparison of the older collections ot 

 observations is consequentlv necessaiy for completeness. 



Every star will be observed twice. Whenever necessary to 

 discover disagreements, a third observation should be made 

 The observations will be differential in their character, and will 

 depend upon a catalogue of 539 zero stars, to be determined at 

 Pulkova. . . 



To facilitate reduction as well as observation, it is recom- 

 mended to the obser\'ers to divide the zones into subzones. It 

 is deemed inexpedient to observe zones of a length ot more 

 than one hour and a half, both on account of the physical 

 fatigue and also the too wide separation of the fixed points of 

 reference. Two zones of one and a half hours each are prefer- 

 able to a single zone of three houi-s. 



The clock error and pole point will be determined altog-ether 

 by means of stars from the Pulkova catalogue, mentioned above. 

 At least two zero stars must immediately precede and follow 

 . • Prepared for this Journal by A. N. Ski.vner, of the Naval Observatory, Wash- 



