MOUNT WILSON OBSERVATORY. 



201 



The conclusion mentioned in the last report, viz, that the systematic 

 errors of the parallaxes measured at Mount Wilson can hardly surpass 

 0':f003, is corroborated by the results for the additional fields. 



In the search for faint stars of large proper motion, for which purpose 

 most of the middle of the nights available for parallax work are used, 

 three additional objects were found, two of them being companions 

 of brighter stars of known large proper motion; they are — 



The magnitudes in the accompanying table are photovisual 

 values derived by Mr. Seares; adopting for the two companions the 

 parallaxes found for the brighter stars, we derive the absolute magni- 

 tudes and the distances from the principal stars (in astronomical 

 units) given in the table. 



A few spectra of faint stars were photographed with a small spec- 

 troscope attached at the 80-foot focus. They include the first star 

 of the above table whose spectrum is found to be Fo, a result cor- 

 roborated by the color-index determined by Mr. Seares, namely, +0.57. 

 The object must therefore be either of very low luminosity for an 

 F-type spectrum or else it must have an exceptionally large velocity. 

 As soon as the parallax is known we shall be able to decide which is 

 the case. 



STELLAR PHOTOMETRY. 



The observational part of the investigations in stellar photometry 

 by Mr. Seares and Mr. Shapley includes 650 photographs, all made 

 with the 60-inch reflector and distributed as follows : Selected Areas, 

 154; clusters, 183; variable stars, 55; color photographs of stars, 219; 

 miscellaneous, 39. 



Photographic Magnitudes for the Selected Areas. 



Very satisfactory progress has been made with both observations 

 and reductions. With the exception of three intercomparison and 

 three polar comparison plates, the photographs for the original program, 

 including Selected Areas 1 to 115, are complete. For the additional 

 zone of 24 areas at —15° declination, 72 per cent of the observational 

 work has been finished. Of the 924 photographs required for the 

 entire program, 50 remain to be secured. 



Relative magnitudes have now been obtained for 123 of the 139 

 areas, and for each of these regions Professor Kapteyn has been 

 supplied with a sequence of provisional standard magnitudes to be 

 used for the reduction of the Durchmusterung photographs of the 

 Selected Areas. In addition, the final magnitudes, which are obtained 



