COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3181


                                        Konkoly Observatory
                                        Budapest
                                        4 May 1988

                                        HU ISSN 0374-0676


                  UBVR-PHOTOMETRY OF BH Cep

  BH Cep (F5 IV) is a rapid irregular variable star with unpredicted Algol-
like light fadings (Wenzel and Bruckner, 1978, Zhelezniakova and Kardopolov,
1980). Zaytseva and Kolotilov (1972) have observed two-components in the
H-alpha emission line with changing profile and intensity.
 We carried out photoelectric UBVR observations of the star using the one-
channel pulse-counting photometer and 0.5 m reflector at Peak Terskol 
(Caucasus, 3100 m). Details of reduction procedure and the reference stars have
been described elsewhere (Pugach and Kovalchuk, 1983).
  During 29 observational nights in 1972-1984 the star showed reasonable light
variations near normal brightness 11m. The amplitude of variations in V does not
exceed 0.5m. We have failed to detect deep light fadings previously reported
by Hoffmeister (1949).
  The recovery rise to the normal brightness was observed on J.D. 2441653.
During 260 minutes of three-colour observations the brightness of the star
increased

       DeltaV = -0.22m  DeltaB = -0.34m  DeltaU = -0.39m

as it is shown in Figure 1. The unusually wide scatter of the U, B, V magnitudes
exceeding the standard deviation should be emphasized.
  In Figure 2 U-B, B-V and V-R colour indices are plotted vs. V magnitudes.
Crosses in the figure represent eight sequential phases of the brightness rise
on J.D. 2441653. While the star gets brighter the colour indices decrease.
The solid lines in Figure 2 represent the "colour - magnitude relation" law:

DeltaV/Delta(U-B) = 2.12; DeltaV/Delta(B-V) = 3.20; DeltaV/Delta(V-R) = 3.81

It strictly coincides with that of interstellar reddening law in the B, V, R
passbands. Then colour - magnitude relations for BH Cep imply that its light
variability should be caused by variable opacity of circumstellar matter
which is like the interstellar one.


                             [FIGURE 1]
                             [FIGURE 2]


  The B-monitoring observations covering the time span of an hour were carried
out on J.D. 2442632. The scatter of the monitoring data is within the photometric
uncertainty. Power spectrum analysis of the monitoring data reveals no periodic
variations exceeding 0.0035 mag.



                        A. F. PUGACH

                        Main Astronomical Observatory of the
                        Ukrainian Academy of Sciences
                        252127 Kiev, USSR.


References :

Hoffmeister, C., 1949, Astron. Nachr., 278, 24. [BIBCODE 1949AN....278...24H ]
Pugach, A.F., Kovalchuk, G.U., 1983, Variable Stars (Moscow), 22, 9. [BIBCODE 1983PZ.....22....9P ]
Wenzel, W., Bruckner, V., 1978, Mitt.Veranderl.Sterne, 8, 35. [BIBCODE 1978MitVS...8...35W ]
Zaytseva, G.V., Kolotilov, E.A., 1972, Astrofizika, 9, 185. [BIBCODE 1973Afz.....9..185Z ]
Zhelezniakova, A.I., Kardopolov, V.I., 1980, Variable Stars (Moscow),21, 301. [BIBCODE 1980PZ.....21..301Z ]