COMMISSION 27 OF THE I. A. U.
      INFORMATION BULLETIN ON VARIABLE STARS
                   NUMBER 418

                               Konkoly Observatory
                               Budapest
                               1970 January 23



     AUTOCORRELATION ANALYSIS OF DQ Her AND RW Tri


      The photoelectric observations of DQ Her and RW Tri
made by M.Walker [1,2,3] were subjected to autocorrelation
analysis. Observations with yellow filter were used. To investigate 
only intrinsic variations all observations at
eclipse (phases from 0.90 up to 1.10) were excluded.

      The standardized coefficient of correlation r(tau) was
calculated by using the formula:

	r(tau) = Sum(U_i*U_(i+tau))/Sqrt(Sum((U_i)^2)*Sum((U_(i+tau))^2));
	tau = n*deltat ; U_i = m_i - m_a;

	where:	n = 1, 2, 3 ... 100.
		deltat = 0.0001 - 8s64
		m_i = observed brightness at a moment i
		m_a = mean quantity of brightness.

The method of correlation analysis for the series with gaps
was described in [4] : Being applied to the observations
concerned such treatment gives a possibility to reveal
periods from 0.5 up to 30 minutes. All calculations were
performed on the M - 220 computer.


                  DQ Her

      Correlation function for DQ Her is shown on
Figure 1. Dots represent the calculated value of r(tau) while
		
			[FIGURE 1]

the solid line is the function

    r_0(tau)=0.86*exp[-(tau/153)^2]+0.07*Cos(2*Pi*tau/116)+0.06*Cos(2*Pi*tau/8.5)

Thus, on the time scale from 0.5 up to 30 minutes the pro-
cess of light variation of DQ Her may be mathematically
represented as a sum of three independent processes:

	a) accidental fluctuations. The term{exp[-(tau/153)^2]}
in the expression of r_0(tau) corresponds to this
process.

	b) harmonic variations{Cos(2*Pi*tau/116)} with the period about
17 minutes, but perhaps with random phase

	c) short-period sinusoidal oscillations{Cos(2*Pi*tau/8.5)}
with the period 71s.71 +- Os.68.

Relative energy contribution of each process is accordingly
1.0: 0.3: 0.2.


	                 RW Tri

      Correlation function for RW Tri is given on Figure 2,
  
			[FIGURE 2]

It seems hardly possible to select any analytical expression
for this curve. From the examination of the Fig. 2 one may
conclude that there are two processes:

      a) accidental fluctuations,
      b) short-period variations with the period 60s.48 +-
        0s.35.

As stated above 1.2 - minute variations of DQ Her have
harmonic shape (see also [5] while 60s variations of RW Tri
reveal pulse features. Neither amplitude nor polarity of
these shortest variations were possible to determine.


                         A.F.PUGACH
                Main Astronomicaly Observatory of the
                  Ukrainian Academy of Sciences,
REFERENCES               Kiev. USSR

1. M.F.Walker, 1956, ApJ 125, N1.
2. M.F.Walker, 1958, ApJ 127, N2. [BIBCODE 1958ApJ...127..319W ]
3. M.F.Walker, 1963, Contr.Lick Obs., N 145.
4. F.I.Lukatskaya, 1967, Perem. Zv., (SU), 16, N 2.
5. R.E.Nather, B.Warner, 1969, MN, 143, 145. [BIBCODE 1969MNRAS.143..145N ]