COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       NUMBER 675

                                         Konkoly Observatory
                                         Budapest
                                         1972 May 16


                   MINIMA OF R CMa


The eclipsing binary, R CMa, was observed photo-electrically in blue light
(Johnson's B Filter) with a 1P21 Photomultiplier attached to the 15-inch
refractor of the Nizamiah Observatory, Hyderabad, India, during the year
1971. BD -15deg1734 and BD -15deg1732 were used as primary and secondary
comparison stars, respectively. The helio-centric times of minimum light,
obtained by using Kwee and Van Woerden's method, (B.A.N. 12, 327, 1956) are
given below:

Minimum (primary)        O-C
J.D.2440971.487         +0.004d
    2440979.439          0.004
    2440995.139          0.006
    2440996.271          0.002

These (O-C)'s are calculated using the ephemeris given by K. Sato (Pub. Ast.
Soc. Jap. 23, 335, 1971):

Min. J.D. 2439140.1448+1.13593876d  E

G.K. Charyulu (Inf. Bull. Var. Stars No. 390) had reported large negative
residuals of -0.196d and -0.192d from similar observations made at the
Nizamiah Observatory. These residuals were derived from the unpublished
ephemeris of E.F. Guinan:

Min. J.D. 2420213.1393+1.13594988d  E

By using the ephemeris given by Sato, these large negative residuals will
reduce to -0.001d and +0.006d respectively. This suggests that the ephemeris
of E.F. Guinan used by Charyulu does not satisfy the observations made during
the period 1967-1971.


M.B.K. SARMA
Nizamiah and Rangapur Observatories
and Department of Astronomy
Osmania University
Hyderabad-7
India



                                [From IBVS 0692]


Correction: Dr. Sarma writes that in IBVS 675 two minima of R CMa were
incorrectly given. The corrected Table is as follows:

Minimum (Primary)         O-C
J.D. 2440971.282       +0.004d
          79.234        0.004
          95.139        0.006
          96.271        0.002


Editors