COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1017 Konkoly Observatory Budapest 1975 July 7 FLARES OBSERVED FROM UV CETI During January 1975 the flare star UV Ceti [R.A.=01h37m22s, Declination= -18d08' (1966.0), visual magnitude 12.9, spectral type dM5.5e] was monitored from Boyden Observatory, using the 41 cm aperture Nishimura Reflector. A Johnson B filter was used for these observations along with an uncooled EMI6256A photomultiplier tube. The table gives details of the observations for a total monitoring time of 33h59m42s. The level of activity over the period was very high, eight definite flares being recorded. Additionally the Table indicates others which were uncertain due to unfavourable observing conditions. In all cases the flares showed the typical characteristic flash phase of UV Ceti type flare stars followed by a gradual decline in activity. The flare peaking at 20h02m57s on the 10-11th January was of particular interest in that it was confirmed visually at the Observatory. A.H. JARRETT and J.B. GIBSON Boyden Observatory Department of Astronomy, University of the Orange Free State, Bloemfontein. Republic of South Africa FLARE SUMMARY FOR UV CETI - JANUARY 1975 ------------------------------------------------------------------------------------------------------------------- Total U.T. (I_o+f - I_o)/I_o Air Date hours Rise Max. Ends Comments mass Max. ------------------------------------------------------------------------------------------------------------------- 01-02 1h19m00s 20h10m485 20h10m50s 20h11m06s Noisy signal at 0.30+-0.08 1.3640 Monitoring Time: 18h53m18s - 20h14m18s end. Very probably U.T. a small flare ------------------------------------------------------------------------------------------------------------------- 02-03 1h38m12s No flares. Conditions Monitoring Time: 19h10m42s - 20h49m42s windy with U.T. 20 51 42 - 20 59 54 slight cloud ------------------------------------------------------------------------------------------------------------------- 03-04 2h15m18s 19h47m54s 19h47m57s 19h48m12s Fairly noisy 0.38+-0.13 1.2973 signal probably a pecursor ------------------------------------------------------------------------------------------------ 19 54 42 19 55 23 20 04 30 Flare 4.62+-0.16 1.3288 19 56 12 19 56 24 - Secondary 0.3 1.3334 Maximum? ------------------------------------------------------------------------------------------------ 20 25 19 20 25 30 20 26 12 Probably a flare, 0.27+-0.17 1.4877 but noisy signal ------------------------------------------------------------------------------------------------ Monitoring Time: 19h19m42s - 21h35m00s U.T. ------------------------------------------------------------------------------------------------------------------- 04-05 2h57m00s No flares Monitoring Time: 19h01m30s - 19h13m10s U.T. 19 16 42 - 22 02 06 ------------------------------------------------------------------------------------------------------------------- 05-06 1h08m00s No flares. Monitoring Time: 20h10m00s -20h21m06s Scattered cloud U.T. 20 31 54 -20 17 48 throughout 21 19 06 -21 35 36 observational period ------------------------------------------------------------------------------------------------------------------- 06-07 3h21m48s 20h11m18s 20h11m20s 20h11m48s possibly a flare 0.47+-0.10 1.4731 but could be a spike. Noisy signal ------------------------------------------------------------------------------------------------ 20 28 56 20 29 05 20 30 00 Flare. Dip in 0.92+-0.15 1.5934 trace preceeds flare ------------------------------------------------------------------------------------------------ Monitoring Time: 18h38m24s -22h00m12s Too windy to continue U.T. ------------------------------------------------------------------------------------------------------------------- 09-10 3h22m24s 19 28 06 19 28 14 19 30 00 Flare 2.00+-0.22 1.3134 ------------------------------------------------------------------------------------------------ 20 15 06 20 15 12 20 16 24 This could be an 3.22+-0.31 1.5779 electronic spike ------------------------------------------------------------------------------------------------ 20 59 37 20 59 51 21 05 00 Flare. Sky 2.17+-0.34 2.0254 brightness rising rapidly at end ------------------------------------------------------------------------------------------------ Monitoring Time: 18h40m24s - 22h02m48s U.T. ------------------------------------------------------------------------------------------------------------------- 10-11 3h31m24s 20 01 49 20 01 56 Complex spike 2.53+-0.15 1.5134 ------------------------------------------------------------------------------------------------ 20 02 22 20 02 40 Spike. Flat 4.74+-0.15 1.5183 topped ------------------------------------------------------------------------------------------------ 20 02 50 20 02 57 Spike. Flare 4.63+-0.15 1.5202 visually confirmed ------------------------------------------------------------------------------------------------ 20 05 24 20 06 42 20 25 00 Slow rising flare. 1.5456 signal was very noisy towards end due to rise in sky brightness ------------------------------------------------------------------------------------------------ Monitoring Time: 18h32m24s - 22h03m48s U.T. ------------------------------------------------------------------------------------------------------------------- 11-12 3h23m00s 21h20m42s 21h20m52s 21h21m00s Spike ? 0.67+-0.14 2.6147 ------------------------------------------------------------------------------------------------ 21 36 43 21 36 50 21 38 00 Precursor 1.17+-0.25 3.0620 ------------------------------------------------------------------------------------------------ Monitoring Time: 18h40m00s - 22h03m00s U.T. ------------------------------------------------------------------------------------------------------------------- 12-13 3h30m42s 19 34 42 19 34 48 Lost in Small slow 0.19+-0.17 1.4001 background flare? measurements ------------------------------------------------------------------------------------------------ 19 37 12 19 37 42 19 54 00 Slow flare 0.43+-0.20 1.4155 ------------------------------------------------------------------------------------------------ 21 14 24 21 14 42 Lost in Slow flare 0.41+-0.33 2.4767 noise ------------------------------------------------------------------------------------------------ Monitoring Time: 18h32m24s - 22h03m06s U.T. ------------------------------------------------------------------------------------------------------------------- 15-16 1h20m30s Very cloudy. No Monitoring Time: 18h39m54s - 20h00m24s fare distinguishable U.T. ------------------------------------------------------------------------------------------------------------------- 16-17 3h02m48s Star very low in sky. Monitoring Time: 18h55m48s - 21h58m54s No flare distinguishable U.T. above noise ------------------------------------------------------------------------------------------------------------------- 18-19 3h09m36s No flare distinguishable Monitoring Time: 18h41m00s - 21h50m48s above noise. Star setting U.T. at end of run. Some moonlit clouds present