COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      Number 1354

                                    Konkoly Observatory
                                    Budapest
                                    1977 October 24




        PHOTOELECTRIC OBSERVATIONS OF THE FLARE

           STAR BD + 13d2618 IN 1973, 1974




    Continuous photoelectric monitoring of the flare star
BD +13deg2618 has been carried out at the Stephanion Observatory
(lambda=-22d49'44", phi=+37d45'15") during the years 1973, 1974 using
the 30 inch Cassegrain reflector of the Department of Geodetic
Astronomy, University of Thessaloniki. Observations have been
made with a Johnson dual channel photoelectric photometer in the
B colour of the international UBV system. The telescope and 
photometer will be described elsewhere. Here we mention only that
the transformation of our ubv system to the international UBV
system is given by the following equations:

      for the time interval from 9-4-1973 to 25-4-1973
                  V = v_0 + 0.039(b-v)_0+1.560
                B-V = 0.737 + 1.033(b-v)_0
                U-B =-1.365 + 1.007(u-b)_0
      for the time interval from 5-5-1973 to 6-5-1973
                  V = v_0 + 0.070(b-v)_0+1.865
                B-V = 0.753 + 1.030(b-v)_0
                U-B =-1.379 + 1.021(u-b)_0
   and for the time interval from 20-4-1974 to 23-4-1974
                 V = v_0 -0.011(b-v)_0+2.445
                B-V = 0.848 + 0.992(b-v)_0
                U-B =-1.632 + 0.999(u-b)_0

   The monitoring intervals in UT as well as the total monitoring 
time for each night are given in the Tables Ia, Ib. Any 
interruption of more than one minute has been noted. In the fourth column
of Tables Ia, Ib the standard deviation of random noise fluctuation 
sigma(mag)= 2.5 log(I_0+sigma)/I_0 for different times (UT) of the
corresponding monitoring interval is given.
   During the 10.23 hours of monitoring time no flare was observed.

        Table Ia
        Monitoring Intervals in 1973
Date    Monitoring Intervals         Total Monitoring   sigma(U.T.)
1973           (U.T.)                     Time
April 20h53m-21h23m,21h27m-21h58m                   0.015(21h01m),0.012
9-10  22 03 -22 27, 00 19 -00 31,                  (21h55m),0.015(22 13),
      00 33 -00 35, 00 59 -01 16.        01h56m         0.014(00 25).
20    19 48 -20 11                          23          0.020(20 09).
22    20 53 -20 56, 21 00 -21 25            28          0.015(21 12)
24-25 20 36 -21 08, 21 12 -21 34,                   0.015(20 57),0.014
      23 12 -23 17, 23 22 -23 32,                  (21 24),0.020(23 54),
      23 36 -23 48, 23 50 -00 04,                    0.024(00 27),0.034
      00 09 -00 22, 00 24 -00 30,                   (01 14),0.037(01 31). 
      00 46 -01 04, 01 07 -01 18,
      01 22 -01 36.                        02 45
25    20 18 -20 39                            21         0.013(20 25)
May
5-6   22 53 -23 01, 23 05 -23 24,                    0.012(22 55),0.014
      23 29 -23 50, 23 53 -00 01,                   (23 15),0.011(23 35),
      00 10 -00 20, 00 22 -00 28            01 12      0.015(00 16)
        Total                               07h05m
        Table Ib
        Monitoring Intervals in 1974
Date    Monitoring Intervals           Total Monitoring     sigma(U.T.)
1974             (U.T)                      Time
April   
20     00h41m-01h23m,01h56m-01h56m                      0.017(01h06m),0.018
       02 00 -02 28,                        01h18m       (02 04)
22-23  23 59 -00 30, 00 33 -00 55,                      0.012(00 12),0.015
       01 02 -01 32, 01 48 -02 12           01 51       (00 38),0.013(01 05),
                                                        0.022(01 53).
                    Total                   03h09m




       G. KAREKLIDIS, F. MAHMOUD, L.N. MAVRIDIS, D. STAVRIDIS

                    H.ZERVAKI - ZOEROU
               Department of Geodetic Astronomy
                  University of Thessaloniki      


Reference:
Andrews, A.D., Chugainov, P.F., Gershberg, R.E. and Oskanian, V.S.
      1969, I.B.V.S. No. 326