COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 640

                                      Konkoly Observatory
                                      Budapest
                                      1972 March 14


           PHOTOELECTRIC OBSERVATIONS OF AD Leo


The flare star AD Leo was monitored photoelectrically in the period of
cooperative observations 8-22 February 1972. The observations were carried out
in the B-band with the 64-cm meniscus telescope. The observational results
are given in Table 1, 2 and figures.

Table 1

Date
1972            Coverage (U.T.)

Feb. 8   18 20-18 33, 18 34-19 42, 19 43-23 04, 23 05-23 20,
         23 23-24 00
     9   00 00-02 51, 02 54-03 02, 18 43-18 44, 18 45-19 40
    10   19 24-19 51, 19 53-20 27
    11   17 53-19 17
    12  (17 40-19 35)
    13   17 26-18 31
    20   17 17-19 29
    21   17 25-19 07, 19 09-21 01, 21 03-23 04, 23 06-24 00
    22   00 00-01 22, 01 29-02 14, 02 17-02 19, 02 22-02 46

                     [FIGURE 1]

Table 2

Date	      U.T.    t_b   t_a  (I_f-I_0)/I_0  sigma/I_o   P_B
1972	    maximum    minutes   maximum

Feb. 9   00 20.3   0.6  24.7   0.36	         0.02        1.92
     9   01 03.9   0.1  1.8    0.11	         0.02        0.06
    20   17 29.6   0.5  4.9    0.25	         0.02        0.50


P.F. CHUGAINOV and N.I. SHAKHOVSKAYA
Crimean Astrophysical Observatory





The continual photoelectric monitoring of the flare star AD Leo was carried out
with the 24 inch telescope at the Konkoly Observatory using an EMI 9502B
photomultiplier and Schott GG 13 + BG 12 filter combination. The limiting
magnitude for the nights was about m_lim= 13.2. As comparison star we used
the companion star at 1.7' NE to AD Leo. The time of monitoring is given in
Table 3.

Table 3

Date of obs.         Coverage UT

1972 Feb. 5    2040-2057, 2059-2116, 2118-2135, 2137-2200,
               2201-2230, 2231-2344, 2254-2319, 2320-2332,
               2333-2359, 2400-2425, 2427-2430, 2431-2455,
               2457-2459, 2500-2529, 2530-2559, 2600-2631,
               2632-2701, 2702-2722, 2724-2732, 2733-2801,
               2802-2830.
     Feb.18    2036-2055, 2056-2110, 2111-2131, 2132-2151,
               2152-2211, 2212-2231, 2232-2251, 2252-2311,
               2312-2331, 2332-2351, 2352-2411, 2412-2431,
               2432-2451, 2452-2501.
     Feb.20    2042-2101, 2102-2121, 2122-2141, 2142-2201,
               2202-2221, 2222-2241, 2242-2301, 2302-2321,
               2322-2341, 2342-2401, 2402-2421, 2422-2441,
               2442-2443, 2445-2501, 2502-2521, 2522-2531.

Total coverage: 16^h00^m

No definite flare activity was noticed.


Konkoly Observatory, Budapest

                            K. BARLAI, L. SZABADOS, B. SZEIDL