[COMMISSION 27 OF THE I. A. U.]
         [INFORMATION BULLETIN ON VARIABLE STARS]


                     I.B.V.S.
                    NUMBER 772

                                     Konkoly Observatory
                                     Budapest
                                     1973 March 8


          VISUAL OBSERVATIONS OF AD LEONIS



The flare star AD Leo was observed visually for a total of
14.4 hours during the January-February 1973 international 
programme by members of the Variable Star Section of the British
Astronomical Association. Hours of coverage are given below,
parentheses indicating poor sky conditions.

1973                  U.T.               Observers
---------------------------------------------------------------
Jan 27   2105-2140,2200-2230,2249-2320   AMS, DK
30       (2037-2248)                     AMS; DK
Feb 1    (2016-2035),(2130-2229)         AMS, DK, JRS
3        2116-2120,(2130-2150),          AMS, DK, KH, RM,
         2150-2236,2318-2400             GP,  DK, FG, PAM
4        0000-0109,(0112-0157),          AMS, KH, RM, GP,
         0200-0351,(0353-0437),          DK,  FG, PAM
         0439-0454
9        2015-2051,2356-2400             DK,  FG, GP, JK, RAP
10       0000-0200                       RAP
---------------------------------------------------------------


The observers were  A.M. Savill, D. Keir, J.R. Savill, K. Hall,
R. McKay, G. Prior, F. Gribbin, P.A. Moore, J. Kent, R.A. 
Paterson.
Slow variations on a time scale of minutes or tens of minutes 
were suspected by several observers, but their reality is
doubted. Six possible flares were recorded:


1973     U.T.     Amplitude   Duration
---------------------------------------
Jan 27   21h05.0m   0.7m        6m
Feb 3    21 49.5    0.6         7
4        00 46.0    0.3         5
         02 49.0    0.7         9
         03 25.0    0.5         3
9        20 47.0    0.3         2
---------------------------------------

Total coverage 14h21m over 5 nights.
                   


British Astronomical
   Association                J.E. ISLES





             CORRECTED PERIOD FOR MT Her

   The following observations were used to determine a more
accurate period for the eclipsing binary MT Her:

Minima
J.D.hel
24.....
  26860,427 H.U. Sandig, AN 278, 1950, 187
  28749,401         "
  31000,210 GK Moscow 1969
  33180,304 H.U. Sandig, AN 278, 1950, 187
  34226,447 M. Kaprowicz, SAC 25, 1954
  34248,409 V. Zonn, PZ 10, 1956, 413
  34907,787 J.C. Koch and R.H. Koch, AJ 67,1962,462
  34960,466 V. Zonn, PZ 10, 1956, 413
  40716,508 Contr.Brno Obs., No. 12, 1971
  40756,989        "
  40759,439        "
  41114,495 Contr.Brno Obs., No. 14, 1972
  41117,417        "
  41154,481        "

The new light elements are:

       JD = 2441117,417 + 0.48771779d
                    +-2         +-29





                         Z. POKORNY
                         Observatory Brno
                         Kravi hora
                         616 00 Brno 16
                         Czechoslovakia