COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                              Number 2985

                                                         Konkoly Observatory
                                                         Budapest
                                                         17 February 1987

                                                         HU ISSN 0374 - 0676


           PHOTOELECTRIC OBSERVATION OF THE FLARE
                 STAR UV Cet IN DECEMBER 1985

  The flare star UV Cet was monitored in cooperation with EXOSAT program
on December 22, 1985 from 16h19m to 18h49m UT and on December 23 from 16h46m
to 20h01m UT using the 1.25 m Cassegrain telescope with a five-channel photon-
counting UBVRI-photometer. The UBVRI bands are close to the Johnson standard
system, 2 sec integration time and 20" diaphragm were used.
   During the first night no flare activity was observed, see Fig. 1 where
records of star+background and background only are shown.


                          [FIGURE 1]


   Note that a flare limit detection in a single integration is 0.3 mag at the
1 sigma level. During the second night rather high flare activity was observed:
five flares are recorded and they are shown in Fig. 2.


                          [FIGURE 2]


   A clear preflare is observed before the last, the most powerful flare.
Few characteristics of the recorded flares are given in Table I :


                 Table I

N    UT_max     t_a   t_b    P  Delta m_u
    23/12/85

1   16h50m.5    0.5   4.2   6.2   1.2
2   17h00m.9    1.5   2.5   4.5   1.3
3   17h38m.7    0.3   3.2   9.4   2.1
4   17h42m.3    0.5   3.8   6.1   0.9
5   18h56m.1    0.2   2.5   7.8   3.2


a. The universal time of the flare maximum, UT_max.
b. The flare duration before and after its maximum, t_a and t_b (min).
c. The equivalent duration of the flare, P (min).
d. The amplitude of the flare in U-band, Delta m_u.



                        I.V. ILYIN

               Crimean Astrophysical Observatory
                    334413 Nauchny, Crimea
                          U.S.S.R.