COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1277

                                                    Konkoly Observatory
                                                    Budapest
                                                    1977 May 17


          ON THE CONNECTION BETWEEN PULSATIONS
         OF RY Sgr AND THE TOTAL LIGHT DECLINES

   1. The analysis of 1926-1974 visual observations of RY Sgr
(1,2,3,4) resulted in conclusion that the period of pulsations
seemed to vary. Averaged of 182 cycles the mean value of period
P equals 38.874d. Figure 1 shows the residuals (O-C)d calculated
with P=38.874d and E0 = J.D. 2424615. The current periods P_i and
corresponding Julian days are given in Table I.

   2. The nine deep minima which occurred in the course of 
observations, did not affect either the phase of pulsations or the
value of period. The beginnings of total light declines are 
indicated by vertical arrows in Fig. 1.

   3. The moments of beginnings of total light declines T_i
seemed to be connected with the phase phi of pulsations and arranged 
within 0.24 <= phi <= 0.37. The initial parts of seven reliable
declines of RY Sgr are shown in Fig. 2. phi_0 corresponds to the
light minimum of pulsations. These fragments are shifted along
time-axis by integral number of cycles. In Fig. 2 observed (ob)
and calculated (cal) minima of pulsations are given.

   The results obtained are as follows:

a. Pulsation period of RY Sgr varies.
b. Cyclic process of pulsations is principal one and does not
   depend on the total light fading.
c. The moments of T_i are synchronized by phase of pulsations
   and consequently are not distributed by "pure chance". A
   serial number of cycles when declines occur is probably
   accidental.

                    [FIGURE 1]
                    [FIGURE 2]

                   Table I

epoch number and Julian days       P_i

E0  =JD..24615 - E40 = JD..26183  39.307d
E40 =    26183 - E153=     30558  38.777
E153=    30558 - E182=     31685  38.874

(168+-1) cycles are omitted for   38.708+-0.232
lack of observations

E350=    38193 - E449 =    42000  38.454


                            A.F. PUGACH

                      Main Astronomical Observatory
                      of Ukrainian Academy of Sciences
                                Kiev



References:

1. Campbell L., Harv. Circ. Nos. 319, 1926; 330, 1927; 344, 1928; 354, 1929;
    361, 1930; 376, 1931; 382, 1932; 407, 1934; 415, 1935
		[BIBCODE 1927HarCi.319....1C ]
		[BIBCODE 1928HarCi.330....1C ]
		[BIBCODE 1929HarCi.344....1C ]
		[BIBCODE 1930HarCi.354....1C ]
		[BIBCODE 1931HarCi.361....1C ]
		[BIBCODE 1932HarCi.376....1C ]
		[BIBCODE 1933HarCi.382....1C ]
		[BIBCODE 1935HarCi.407....1C ]
		[BIBCODE 1936HarCi.415....1C ]
2. Campbell L., Harv. Ann. 104, 1938; 107, 1940; 110, 1945; 116, 1948
		[BIBCODE 1938AnHar.104....1C ]
		[BIBCODE 1940AnHar.107....1C ]
		[BIBCODE 1945AnHar.110....1C ]
		[BIBCODE 1948AnHar.116..124C ]
3. Bateson F.M., New Zealand Circ.Nos. 120, 1965; 127, 1966; 133, 1967; 134,
    1968; 147, 1969; 168, 1970; 184, 1971
4. Bateson F.M., Publ. VSS RAS of New Zealand 1, 33, 1974