COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 484


                                Konkoly Observatory
                                Budapest
                                1970 November 5


              FLARES OF UV CETI

      During the recent International Co-operative period
from the 22nd September to the 9th October, 1970, the flare
star UV Ceti was monitored at Boyden Observatory for a total
tine of 25h19m. The 40 cm aperture Nishimura telescope was
used for this work, fitted with a Johnson B. Filter and a
solid carbon-dioxide cooled E.M.I. type 6256 photomultiplier
tube.
      The table gives full details of the monitoring
period. It will be seen that fifteen flares were recorded
during the period, several of them being classed as major
flares, especially Nos. 4, 8 and possibly Nos. 10 and 11.



                        Monitoring Table of UV Ceti

Date        U.T.        Total   Flare   U.T. of                     delta m
                        hours    No.     flare        Duration
                        per
                        night

Sept.
20-21   20h13m-20h40m   
        20 58 -21 34    1h03m
21-22   19 23 -22 41    3 18     1      22h02m0         5m0          0.58   
22-23   19 00 -22 30    3 30     2      20 55.0         2.2          0.57   
23-24   20 52 -22 13    1 21     
30-

Oct.1   18 23 -23 12    4 49     3      19 05.5         6.5          0.44   
                                 4      21 13.1         8.9          1.53   
                                 5      22 48.2         1.6          0.59   
                                 6      22 53.3         2.7          0.99   
Oct.                           
 1-2    18 17 -22 45    4 28
 4-5    18 07 -22 55    4 48     7      18 54.4         1.2          0.53
                                 8      20 50.1        23.9          2.56   
                                 8a        -             -           1.90   
                                 8b        -             -           0.88   
                                 9      21 42.0         2.0          0.96   
                                10      22 03.5         4.0          1.10    
 5-6    18 38 -20 40     2 02   11      18 03.5         4.0          1.10           
                                12      19 05.5         5.5          0.88   
                                12                                   0.52   
                                
                 Total  25h19m


                        [FIGURE 1]
                        [FIGURE 2]

      Flare No.8 is particularly interesting In that it
shows characteristics similar to those recorded during
previous observations of UV Ceti by Eksteen. It was of an
appreciable duration, of the order of 25m. In this connection 
it is also of interest to compare the profile with that
obtained during a major flare of UV Ceti during the 5th-
8th October 1967 (previously not published).

                                U.T. of   Duration    Delta m
                                 flare

Flare of 5-8th October 1967,   23h40.9m      1.1m       0.66
                               23 44.0       25.0       0.48
                                                        0.81
                                                        0.90
                                                        1.14


The level of activity during the monitored period was quite
high; the mean amplitude being approximately Delta m = 1.
      It should be pointed out that with respect to flare
No. 3 the maximum is not shown as it was missed during 
recording of the background sky intensity - hence the values
for duration and Delta m should be taken with some reservation
in this case.


                        A.H. JARRETT
                        J.P. EKSTEEN

                     Department of Astronomy,
               University of the Orange Free State,
                        P.O. Box 339
                        BLOEMFONTEIN
                     Rep. of South Africa


Ref: J.P. Eksteen, 1968, MNASSA. Vol. XXVII, page 145. [BIBCODE 1968MNSSA..27..145E ]