COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 1739

                                     Konkoly Observatory
                                     Budapest
                                     1980 February 5


       FLARE LIKE ACTIVITIES IN ECLIPSING BINARY DI Peg


The eclipsing binary DI Peg (BD+14d5006, HD 220619) was selected for UBV
photometry because earlier photometric investigations drew attention to its
interesting nature (Jensch, 1934, Rucinski, 1967 and Binnendijk, 1973).
Rucinski (1967) derived an orbital solution by assuming 24% extra light in V
light. The magnitude and spectral type, according to him, are:

Magnitudes: U=9.96m, B=9.92m, V=9.45m
Spectral type: F4 + G9 to K1.

The system was observed with the 104-cm telescope of Uttar Pradesh State
Observatory using the conventional d.c. techniques of photoelectric photometry
to obtain the full UBV light curves. The telescope is equipped with a
refrigerated EMI6094S photomultiplier and standard UBV filters. A diaphragm
covering 15 arc sec of the sky was used to exclude a nearby companion of
magnitude ~14 (visual estimate).

During four nights (17, 18 October and 11, 12 December 1979), we had about 15
hours of total observation. On December 12, 1979 during the secondary minimum
two flares were observed.

Figure 1 and 2 show the light curves of the observed flares in B filter. The
characteristics of the flares are given in Table I. Delta m_B is the
difference in instrumental B magnitude between the steady flux and peak of the
flares and F(z) is air mass at the time of the peak of the flares.

                        [FIGURE 1]
                        [Figs. 1-2]

Table I

Flare No.  Time of              Duration
          occurrence      rise time   decay time    F(z)   Delta m_B
        of peak in U.T.   in minute   in minute
1        16h 38.8m           0.4         9.5        1.713   0.31m
2        17  36.0            0.2         4.9        2.529   0.44

It can be seen from Table I and Figures 1 and 2 that the ratio between the rise
time and decay time of both the flares are similar to the other flares observed
in AD Leo, YZ CMi and UV Ceti (Sinvhal and Sanwal, 1977).

Acknowledgements: We would like to express our thanks to Drs. M.C. Pande,
S.C. Joshi, C.D. Kandpal and to Mr. B.B. Sanwal for their helpful
discussions and valuable remarks.


U.S. CHAUBEY
Uttar Pradesh State Observatory
Naini Tal, 263129, India

References:

Binnendijk, L.: 1973, Astron. J. 78, 97 [BIBCODE 1973AJ.....78...97B ]
Jensch, A.: 1934, Astron. Nachr. 252, 396. [BIBCODE 1934AN....252..393J ]
Rucinski, S.M.: 1967, Acta Astr. 17, 271 [BIBCODE 1967AcA....17..271R ]
Sinvhal, S.D. and Sanwal, B.B.: 1977, I.B.V.S. No. 1263