COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1110

                                    Konkoly Observatory
                                    Budapest
                                    1976 March 3


V1, THE ONLY KNOWN CEPHEID VARIABLE IN THE GLOBULAR CLUSTER NGC 6752;
                  OBSERVATIONS AND PERIOD



   The period (1.37d) of this remarkable star was found independently
by Lee (1) and by Wesselink (2) at about the same time. Lee's work was
done at Siding Spring, Australia; Wesselink made use of plates taken
at the Radcliffe Observatory, South Africa and of plates obtained at
the Yale-Columbia Observatory in South America.
   Since then 23 more South American plates of the star became available.
This new material is in accord with the earlier results.
   Table I gives the details of the B photometry done on South African
material. Table II, similarly, gives the South American B results presently
available.


                             TABLE I
                      South African Plates
                 (74-inch Radcliffe Reflector)


             2430000 +                  2430000 +
                        Ph     B                   Ph     B
             3539.30   .14    13.05    7433.58    .86    13.70
             3895.34   .49    13.68    7433.59    .86    13.59
             5364.24   .33    13.34    7845.53    .77    13.67
             5366.27   .80    13.90    7847.45    .16    12.90
             5366.29   .82    13.90    8172.60    .10    13.00
             6456.22   .68    13.92    8172.62    .11    13.05
             6697.64   .85    13.44    8172.63    .12    13.00
             7198.23   .09    13.11    8172.64    .12    13.05
             7198.26   .11    13.11    8230.47    .09    13.11

                          TABLE II
                    South American Plates
                  (20-inch Y - C Astrograph)


      2440000+                   2440000+
                       ph     B                    Ph     B
             828.55   .27   13.11       1926.67   .08   13.07
             829.55   .00   13.00       1926.69   .09   13.11
             830.54   .72   13.72       1926.72   .11   13.00
             832.56   .18   12.98       1926.75   .13   13.00
             834.56   .63   13.74       1927.49   .67   13.81
             835.55   .35   13.40       1927.52   .69   13.89
             836.58   .10   12.92       1927.55   .71   13.89
             854.55   .14   12.90       1927.58   .74   13.89
             857.55   .31   13.22       1927.61   .76   13.89
             858.55   .04   13.05       1927.64   .78   13.89
            1897.67   .03   13.16       1927.67   .80   13.81
            1926.50   .95   13.16       1927.70   .82   13.81
            1926.52   .97   13.25       1927.73   .84   13.45
            1926.55   .99   13.16       1927.76   .87   13.45
            1926.58   .01   13.16       1948.50   .92   13.45
            1926.61   .03   13.11       1949.52   .66   13.81
            1926.64   .05   13.16



   The B magnitudes are on Lee's photometric system, allowing a direct
comparison with the Lee photometry. Instead of the more accurate heliocentric 
values, geocentric Julian Dates have been given as being good
enough.
   The Australian, South African and South American data were used
for a new discussion of the period.
   It was found that the constant period 1.378156d +- 0.000006 (s.e.)
gives a satisfactory representation of all the available observations
over an interval of 23 years.
   The corresponding reciprocal period is 0.725607+- 0.000003 (s.e.)
   The phases as given in Table I and Table II were calculated from
the formula


   Phase = 0.725607 x (JD - 2430000)


Corresponding to this formula, the phase of maximum light is 0.16.
   The new ephemeris is


     JD of maximum = 2441000.67 + 1.378156 x E


   Future observations are needed to check the constancy of the period
to higher accuracy.




                          A. J. WESSELINK
                          Yale University
                          New Haven, Connecticut
                          U.S.A.
References:


Lee, S.W., The Observatory, Vol. 94, 74 (1974). [BIBCODE 1974Obs....94...74L ]
Wesselink, A.J., I.A.U. Inf. Bull. 895. [IBVS 895]