COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 403

                               Konkoly Observatory
                               Budapest
                               1969 November 12


 OBSERVATIONS OF EV Lac DURING THE INTERNATIONAL CAMPAIGN
              SEPTEMBER 4-19, 1969


      The results obtained from our photoelectric observations 
of EV Lac carried out at the Catania Observatory
stellar station in Serra La Nave during the international
patrol planned for the period September 4-19, are given
below.
     A quasi-cassegrain reflector of 81 cm aperture, a
photometer employing an EMI 6256 S photomultiplier (spectral
response S 13) and a BG 12 (1 mm thick) plus a GG13 (2 mm
thick) Schott filters were used. The resulting effective
wave length was 4300 A.
      The total light of EV Lac plus its optical companion 
was measured. In order to eliminate the light contribution 
of the optical companion, the. observed intensities
were corrected with the following equation: I_(EV Lac) = 0.70
I_observed, deduced according to the B magnitudes of the two
above mentioned stars given by Andrews (1989).
      The obtained data are given in Table 1 and 2. No
transformations to the standard UBV system were applied,
therefore the b lights quoted in the Tables are those of
our natural system. The graphs show the light curves of the
observed flares.

      In the least column the sky condition is given by
the following standards:
     0 = very clear  2 = with some thin layers
     1 = clear       3 = extended thin stratus

     The following people have collaborated in the observations: 
A. Cali, R. Barbagallo and V. Stancanelli.



                        Table 1
                Intervals of the effective time coverage.
             (Interruptions shorter than 1^m are not noted)

Sept                    Coverage (U.T.)         T.C   m_lim -m_0
04      00h00h-0112;    0114-0228; 0237-0308;      
        0311-0329.                              195^m   4m10   
04-05   1956-2019;      2030-2042; 2050-2056;        
        2102-2114;      2154-2159; 2207-2214;
        2216-2220;      2223-2333; 2337-2417;
        2427-2626;      2628-2710; 2712-2714;   342     4.39
05-06   1907-1913;      1950-2022; 2027-2132;   103     4.20
06-07   1901-2016;      2023-2032; 2040-2209;
        2213-2243;      2317-2338; 2352-0011;   
        0013-0110;      0117-0302; 0306-0313;   412     4.04
07-08   2322-0014.                               52     4.01
11-12   1918-1928;      1931-1951; 2016-2108;   
        2128-2135;      2137-2202; 0129-0134;   
        0136-0213;      0215-0245; 0247-0300;   
        0312-0325.                              212     4.24
12-13   1936-2019;      2027-2109; 2137-2222;
        2228-2248;      2250-2330; 0034-0101;   
        0113-0130;      0205-0231; 0236-0249;
        0251-0301;      0306-0330.              307     4.38
15-16   1945-2029;      2036-2114; 2123-2136;   
        2139-2159;      2218-2301; 2308-2346;   
        2350-0015;      0034-0038; 0055-0134;   
        0137-0142;      0144-0212; 0235-0257;   
        0259-0331.                              351     4.47
16      1910-1919;      1921-1952; 1954-1956;   
        2004-2046;      2056-2134; 2141-2154;   
        2202-2211;                              144     4.63
17-18   1936-2020;      2034-2117; 2126-2213;   
        2216-2227;      2240-2325; 2332-0016;   
        0049-0100;      0130-0214; 0227-0312;   
        0320-0335.                              349     4.67
18-19   2011-2100;      2107-2204; 2217-2302;   
        2313-2323;      2331-0015; 0023-0118;   
        0123-0207;      0214-0258; 0305-0316;   
        0318-0334;                              375     4.91
19      1926-2012;      2025-2110; 2118-2203;         
        2216-2225.                              145     4.08

T.C = Total coverage per night
 m_lim - m_0 = -2.5 log (3 sigma/I_0), where sigma represents the
standard deviation of the random noise fluctuation for a
night, and I_0 represents the mean intensity of the quiet
star during the same night.


                         [FIGURE 1] 
            
                        Table 2
                   Observed flares

No  Sep  t_b     t_max      t_e     m_1_+ -m_0  (m_f_+ -m_0)m  P    secz   sky
1   06  20h03.7m 20h04.3m  20h09.0m  4.10        1.46         0.33m 1.3180  0
2   06  22 14.6  22 16.05  22 19.5   4.16        1.38         0.51  1.0458  1
3   06  22 35.5  22 35.8   22 42.0   4.17        2.30         0.35  1.0288  1
4   07  00 44.3  22 44.5   00 46.0   4.11        0.97         0.17  1.0294  2
5   12  22 13.9  00 14.5   22 18.6   4.72        0.65         0.80  1.0379  0
6   16  02 45.7  02 45.8   02 47.8   4.37        0.55         0.19  1.3384  1

t_b = U.T. of the beginning; t_max = U.T. of the maximum intensity;
t_e = U.T. of the end; m_1 - m_0 = -2.5 log ( 3 sigma / I_0)
where sigma and I_0 indicate the standard deviation of the 
random noise fluctuation and the mean intensity of the
quiet star, near the observed flare, respectively;
(m_f - m_0)_m = -2.5 log [(I_0+f - I_0)/I_0]_max, where I_0+f is the
intensity deflection due to EV Lac (I_0) plus that of flare
(I_f) at maximum; P= Integral ( I_0+f - I_0)/I_0 dt, integrated intensity
in minutes.


Catania astrophysical Observatory, Italy
October 25, 1969



                    S. CRISTALDI and M. RODONO

Reference
Andrews, A.D. 1969, Comm. 27 IAU, Inf.Bull.var.Stars, No. 370.