COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 523


                              Konkoly Observatory
                              Budapest
                              1971 February 23



        PHOTOELECTRIC OBSERVATIONS OF YZ CMi

      Photoelectric monitoring of YZ CMi was carried out
at the Byurakan Observatory with the 50 cm reflector in the
time interval January 16 - February 2, 1971, as proposed by
the "working group". The observations were made with a
standard B Filter.
      The observational data are summarized in Table I.
They are presented in the form proposed in IBVS 488.




                            TABLE I
---------------------------------------------------------------------------
Date                                             sigma/X_s        F(z)
UT       Coverage   UT_max   t_b   t_a                       P         
1971        UT                          X_fM/X_s                     Remark
---------------------------------------------------------------------------
Jan.
21      1740-2019                                  0.072                1
        2021-2100
28      1935-2200   21h9.3m   0.8 35.5    22.4     0.158  102.0   1.30  2
        2210-2300
29      1732-2239                                  0.080
Feb.
1       1700-2210   21 29.1   1.6 14.9     2.9     0.103   20.8   1.35
---------------------------------------------------------------------------
        Total coverage: 1010 minutes.


Remarks:
1.- The rather great values of sigma/X_s are due to the fact
   that all the observations were effectuated under very
   poor weather conditions.

2.- The light curves of flares are presented in the figures.
   The ordinate is given in the units of X_f/X_s.


                          V.S. OSKANIAN
                         Byurakan Observatory
                             USSR


                   [FIGURE 1]




Correction to IBVS No 503 (HS Her):


       The last term in the equation should read:

               +0.017d sin (360d E/3450)