COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2207

                                   Konkoly Observatory
                                   Budapest
                                   1982 October 13

                                   HU ISSN 0374-0676


         PHOTOELECTRIC OBSERVATIONS OF MT Her



    The variability of this star was discovered by
Hoffmeister (1935). Kukarkin et al. (1974) list the star
as having an Algol type light curve with light elements:
2441117.417 + 0.4877 1779E, an out-of-eclipse brightness
(approx. pg) of 11.8 mag., and F5 spectral type. The ephemeris
comes from Pokorny (1973), who listed a number of older
times of observed minima in which a number of Warsaw based
observers participated, and this was used to calculate
phases for the presently reported observations. Among
Pokorny's sources is Zonn (1956), whose finding chart and
comparison stars were also used in the present work.
    Photoelectric observations of MT Her through filters
which could directly be related to standard B and V
magnitudes were made using the 74 inch reflector at Kottamia
(Egypt) over a period of 5 nights between 3 and 10 July,
1981. Zonn's (op.cit.) star c provided the main comparison,
while occasional checks were made on his star a. A full
description of the observing equipment was given in Murad's
(1982) thesis, and it was also referred to in another recent
Bulletin (Kadouri, 1981). A new feature of this equipment
is that of digital data processing.
    The differential B and V light curves (variable-comparison)
are shown in the accompanying diagram - the first such 


                         [FIGURE 1]


photoelectrically obtained curves, as far as we are aware. They
suggest a beta-Lyrae type character of the light variation (c.f.
Kukarkin et al.'s (op. cit.) designation!), together with
some asymmetry about the secondary minimum, which like the
primary, appears to occur slightly before prediction. The
accompanying diagram comes from data measured from the
ratemeter driven chart recorders; the simultaneously
acquired but more copious quantity of digital information
only repeats the same overall features.



    These light curves should be analysed in more detail
subsequently.





      E. BUDDING           I. M. MURAD

      Carter Observatory   Department of Astronomy
      P.O. Box 2909        The University
      Wellington 1         MANCHESTER
      NEW ZEALAND          M13 9PL





References:

Hoffmeister, C.: 1935, Astron. Nach., 255, 405. [BIBCODE 1935AN....255..401H ]

Kadouri, T. H.: 1981, Inf. Bull. Var. Stars, No. 2057.

Kukarkin, B. V., Kholopov, P. N., Efremov, Y. N.,
    Kukarkina, N. P., Kurochkin, N. E., Medvedeva,
    G. I., Perova, N. B., Pskovskii, Y. P., Fedorovich,
    V. P., Frolov, M. S.: 1979, Second Supplement to
    Third Edition of General Catalogue of Variable
    Stars, Moscow.

Murad, I. M.: 1982, M.Sc. thesis, University of Manchester
     (unpublished).

Pokorny, Z.: 1973, Inf. Bull. Var. Stars, No. 772.

Zonn, V.: 1956, Perem. Zvezd, 10, 413. [BIBCODE 1955PZ.....10..413Z ]