COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 564


                                 Konkoly Observatory
                                 Budapest
                                 1971 June 26




        ON THE APPARENT NON-VARIABILITY OF ADS 9975


The variability of one component of the visual
binary ADS 9975 (BD +47d2317 = HD 146327) has been suggested 
recently (Dommanget and van Dessel 1970). The separation
of the components has always been found to be less than
0.6 seconds of arc. The Henry Draper Catalogue lists a
spectral type of G0. The above authors, via a literature      
search, found that the Delta m between the two components varied
widely, and so suspected a possible variation of one of the   
components. They determined the absolute magnitudes to be
M_v(A) = 5.64 and M_v(B) = 6.64. The color estimates that one
can make, the approximate spectral types, and the apparent
change in Delta m of the visual double cause one to suspect a
system similar to ADS 9537 (Batten and Hardie 1965), where
the components of the binary are both W Ursae Majoris
systems.
       To test whether a W Ursae Majoris-type eclipsing
binary might be one component of ADS 9975, differential
photoelectric observations were undertaken at Kitt Peak
National Observatory with the 16-inch and 36-inch  telescopes
in October, 1970 on nights only good enough for differential
photometry. The nearby star HD 146450 was used as the 
comparison star. Nineteen observations on five nights (14 of 
the observations being on one night) indicate a constant
difference between ADS 9975 and HD 146450 of 1.522+-0.008
magnitudes. During this 5 day interval, then, ADS 9975 seems
to have been constant in brightness. It would seem that any
variation in brightness would be of a long term nature.
        This work was supported in part by the National
Science Foundation.



                         ARLO U. LANDOLT
                         Louisiana State University
                         Observatory
                         Baton Rouge, Louisiana 70803
                         USA

Reference:

Dommanget,J. and van Dessel, E.L. 1970,  Astron. and Astrophys. 
   6, 423. [BIBCODE 1970A&A.....6..423D ]
Batten, A.H. and Hardie, R.H. 1965, Astron. Jour. 70, 666. [BIBCODE 1965AJ.....70..666B ]