40 



contains 529 stars. For standard magnitudes 47 stars were used, the 

 brightness of which was estimated by Küstner or determined by 

 means of gauzes bj' Zuhhellen. 

 We find from 4 determinations: 



rr = ü''.ü02 ±0".0001. 



]\lessier 37. 



N. G. C. 2099; «,„„„ = 5''45'".8, d,,„„ = -f- 32°3J', /; = + 4°, 

 / = 145°; class: D\. 



J. 0. NoRDi.uND. Pliotographische Ausmessung des Sternhaufens 

 Messier 37. Inaug. Diss. Upsala 1909, Arkiv f<)r Matematik, Astro- 

 nomie och Fjsik, Band 5, N". 17. 



Dr. H. GiKBKLEK. Der Sternhaufen Messier 37. Veröffentl. Kgl. 

 Sternwarte zn Bonn, W. 12. J914. 



NoRDLUND measures 4 plates and gives the places and magnitudes 

 of 842 stars. The magnitudes are derived from the diameters according 

 to the formula of Charlikr by means of 214 standard magnitudes 

 that have been determined photometrically by Von Zeipel. Many of 

 the bright stars of the cluster are red (colour index > 0"'.7), e.g. 

 some 50 or 70 7o of the stars of the lO^'^ magnitude. 



GiEBELER discusses 2 plates taken by Küstner and measured by 

 Stroe[-e. The catalogue contains 1231 objects. The magnitudes have 

 been joined with Nordlund's scale by comparing those of 450 stars. 

 For the red stars too the photographic magnitude is given. 



For our puipose it is a drawback that for the red stars the 

 photographic magnitude is mentioned. This is why the brightest stars, 

 among which many red ones occur, could not be used by us. Excluding 

 these we find from 4 determinations: 



71 = 0".002'^ ± 0".0004. 



Messier 36. 



N. G. C. I960; .^,.„ = 5''29'".5, d,,„„ = + 34° 4', /. =: + 2°, 

 /=:142°; class: D2. 



Dr. S. Oppenheim. Ausmessung des Sternhaufens G. C. N". 1166. 

 Publ. der v. Kuffner'schen Sternwarte in Wien, Bd. Ill, pag. 271-307, 

 1894. 



Measurements of three photographic plates. The catalogue contains 

 200 stars. The magnitudes wei-e derived from the diameters, measured 

 in connection with estimates of visual magnitudes found by Dr. Palisa 

 for the greater part of the stars. 



The interval of magnitudes is small. We find from 3 determinations: 

 7T=:0".005 ± 0".001. 



