COMMISSION 27 OF THE I.A.U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 135

                                        Konkoly Observatory
                                        Budapest
					16 May 1966

		NOTE ON THE AMPLITUDE OF RU CAM

	Fernie and Demers (Ap. J., in press, as reported by Wamsteker
(1966) have reported recently that the light amplitude of RU
Cam became very small during the season of 1965/66. It may be of 
interest to quote here some photometric results obtained for this star
by the present writer during the two seasons of 1961/62 and 1963/64
(all the observations were made at the Lick Observatory).
	In 1961/62 RU Cam showed an extremely large amplitude in
V amounting to about 1.6 mag (see Michalowska-Smak and Smak 1965
for details). Photoelectric observations of various observers made in
the 1950's showed that between JD 2434000 and JD 2435500 the visual
amplitude was only about 1 mag, but around JD 2435900 Delsemme
and Delsemme-Jehoulet (1958) reported V_min = 9.55 which gave for
the amplitude 1.3-1.4 mag. Therefore between JD 2435500 and JD
2437700 there was a systematic increase in the amplitude from 1.0
mag to 1.6 mag, primarily due to the decrease of the star's 
brightness at minimum.
	In 1963/64 the writer obtained only four measurements of RU 
Cam; they are given in the table below. When plotted against phase
and compared with the 1961/62 observations these data show that
	a) the visual light amplitude was only about 0.55 mag;
	b) the B-V variations showed much smaller amplitude than
those in 1961/62; and
	c) there was no significant phase shift between the two
seasons.

                      [FIGURE 1]

 RU Cam in 1961/62 (filled circles) and in 1963/64 (crosses)

	Moreover, the 1963/64 data together with the new observations 
by Wamsteker (1966) show clearly that RU Cam became both - fainter
at maximum and brighter at minimum - as compared to earlier observations.
	Photoelectric observations of RU Cam in 1963/64

	JD hel		Phase     V	B-V	U-B
     2438365.74          0.77    8.49   1.26    1.07
         429.68          0.66    8.45   1.16    0.99
         430.66          0.70    8.46   1.22    1.06
         438.72          0.07    8.99   1.32    1.06

	Phases were computed from the elements given in the General
Catalogue of Variable Stars.


Institute of Astronomy,
Polish Academy of Sciences,
Warsaw, Poland
May 2, 1966

						J. SMAK

References

Delsemme, A. H. and Delsemme-Jehoulet, D. 1958. Mem. Soc. Roy.
   Sci. Liege, 4-e Serie, 20, 328.
Michalowska-Smak, A., and Smak, J. 1965. Acta Astron., 15, 333. [BIBCODE 1965AcA....15..333M ]
Wamsteker, W. 1966. IAU Information Bull. on Variable Stars, No 128.