( 697 ) 



Class 



I numb 

 ;of neb. 



p.e. 



We thus finallj' get for the mean yearly parallax 



— 0"00J3 ±0"0012 (168 nebulae) (3) 



This is the parallax relative to stars of comparison the mean 

 magnitude of which is 



8.75 



Meanwhile, as mentioned before, Mönnichmeyer applied p. m. to 

 7 of his 183 stars of comparison. 



If he had refrained from doing so, we sliould have found the 

 parallax 0"000-l smaller. We thus have in conclusion : 



Mean parallax of the 168 nebulae relative to stars of comparison 

 of the mean magnitude 8.75. 



— 0017 ± 012 (p.e.) (4) 



In N°. 8 of the Publ. of the Astr. Laboratory at Groningen the 

 mean parallax of the stars of magnitude 8.75 was found to be 



0"0063 (5) 



To this value we might apply two corrections : 



