COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2744

                                       Konkoly Observatory
                                       Budapest
                                       11 June 1985

                                       HU ISSN 0374 - 0676


       PHOTOELECTRIC PHOTOMETRY OF DI CEPHEI DURING 1981-1984


  The T Tauri type variable star DI Cephei (Kholopov, 1952) was observed
at the mountain station of the Konkoly Observatory. The measurements were
carried out with an unrefrigerated photoelectric photometer, attached to the
102 cm Ritchey-Cretien telescope of the observatory. The identification chart
is shown in Figure 1.
  On several nights DI Cephei was monitored in order to record flare-like
activity in the U band. As Figures 2-5 show, there are irregularities on
the light curve, especially in the U band. The most convincing flare-like
events occurred on the night 10/11 September 1983 (J.D. 2445588.5702).
  In that case the amplitude of the brightening reached about 3 magnitudes
in U band, about 0.8 magnitude in B band and about 0.4 magnitude in V band.
  Table I shows the observed average brightnesses during the monitoring
intervals, where the first column gives the calendar date, column 2 the
J.D. of the beginning and the end of measurements. One moment represents
the middle of the monitored time interval. Columns 3-5 give the average
UBV magnitudes.


                               [FIGURE 1]

 Figure 1: Identification chart for the variable and comparison stars.


                               [FIGURE 2]

 Figure 2: Light curve based on the 08/09 Sep. 1983 (J.D.2445586.3098-
           .6255 observations.

                               [FIGURE 3]

 Figure 3: Light curve based on the 10/11 Sep. 1983 (J.D.2445588.3361-
           .6292) observations.

                               [FIGURE 4]

 Figure 4: Light curve based on the 04/05 Oct. 1983 (J.D.2445612.3350-
           .6076) observations.



                               [FIGURE 5]

 Figure 5: Light curve based on the 05/06 Oct. 1983 (J.D.2445613.2545-
           .5855) observations.

                               [FIGURE 6]
                               [FIGURE 7]

 Figures 6-7: The observed average values on the V-B and V-U plane. The
              area encircled with solid lines means the observed
              boundaries of previous measurements. (Drawing after the
              graphs published by Gahm and Petrov. 1983).




                Table I
Date            J.D.(244...)      V       B        U
16/17.07.1981   4802.5044         11.36   12.58   12.64
27/28.03.1982   5056.6444         11.73   12.97   13.5
08/09.09.1983   5586.3098-.6255   11.51   12.53   12.42
10/11.09.1983   5588.3361-.6292   11.52   12.49   12.53
04/05.10.1983   5612.3350-.6076   11.56   12.64   13.16
05/06.10.1983   5613.2545-.5855   11.4    12.3    12.1
01/02.09.1984   5945.5597         11.58   12.51   12.63
04/05.09.1984   5948.6220         11.5    12.51   12.16
05/06.09.1984   5949.5976         11.58   12.54   12.6


  Figures 2-5 show the DeltaV deltaB and DeltaU light curves in the monitored interval.
  DI Cephei shows remarkable variability pattern on the V - B and V-
U plane (Gahm and Petrov, 1983). The new observations are in good agreement
with that pattern but the measured magnitudes are greater than the previous
ones.
  Figures 6-7 show the new data plotted on the graph from the publication
of Gahm and Petrov.





                            JANOS KELEMEN
                            Konkoly Observatory
                            Budapest, Hungary





References:
Kholopov, P.N., : 1952, Variable Stars, 9, 157
Gahm, G.F., Petrov, P.P., : 1983, Activity on Red Dwarf Stars Proc. IAU Coll.
      No. 71, (Edited by P.B. Byrne and M. Rodono), p.497. [BIBCODE 1983ASSL..102..497G ]