COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1105 Konkoly Observatory Budapest 1976 February 26 FLARE SUMMARY FOR UV CETI SEPTEMBER 27 - OCTOBER 14, 1975 At the end of September and for two weeks in October 1975, the flare star UV Ceti (RA = 01h37m12s, decl.=-18d08' (1966.0)), visual magnitude 12.9, spectral type dM5.5e) was monitored from Boyden Observatory with the 41 cm aperture Nishimura Reflector. The detector was a dry ice cooled EMI6256A photomultiplier tube. A standard Johnson B. filter was used throughout the observations. The Table gives details of the observations over a total monitoring time of 77h04m24s. Throughout the period level of activity was reasonably high, twenty-six flares being noted. There were many other which are marked as uncertain due to unfavourable observing conditions. Especially interesting is the very intense flare peaking at 01h35m21s U.T. on the 10th October. Although we have recorded larger flares from UV Ceti,this one was very prominent with an ((I_0+f)-(I_0))/(I_0) value of approximately 17.7. Also on the 10th another relatively intense flare of. ((I_0+f)-(I_0)/(I_0) value 8.3 peaked at 23h39m48s. Both these flares showed the characteristic flash phase followed by the gradual decline of UV Ceti type flare stars. They are similar in contour to those recorded on previous occasions from UV Ceti by A.H. Jarrett, J.P. Eksteen and J.B. Gibson. A.H. JARRETT and J.B. GIBSON Boyden Observatory, Department of Astronomy University of the Orange Free State Bloemfontein, Republic of South Africa References: 1. Jarrett A.H. and Eksteen J.P., 1969, I.B.V.S. No. 349 2. Jarrett A.H. and Eksteen J.P., 1969, I.B.V.S. No. 406 3. Jarrett A.H. and Eksteen J.P. 1970, I.B.V.S. No. 412 4. Jarrett A.H. and Eksteen J.P. 1970, I.B.V.S. No. 434 5. Jarrett A.H. and Eksteen J.P. 1970, MNASSA, 29, p. 115 [BIBCODE 1970MNSSA..29..115J ] 6. Jarrett A.H. and Gibson J.B. 1975, I.B.V.S. No. 979, 7. Jarrett A.H. and Gibson J.B. 1975, I.B.V.S. No. 1017. Flare Summary for UV Ceti - September 27 - 19 October 1975 Date Total Rise Max. Ends Comments ((I_0+f)-(I_0))/(I_0) Air Hours (U.T.) Mass Max. 27th 3h20m30s 20h36m02s 20h36m06s 20h36m36s Possibly a small flare 0.26+-0.092 1.3172 20 38 51 20 38 57 20 39 11 Possibly a small spike 0.45+-0.082 1.3052 This is 21 03 46 21 03 48 21 04 30 Small spike 0.81+-0.09 1.2150 probably 21 04 46 21 04 51 21 05 18 Poss. a small slow flare 0.31+-0.09 1.2117 one event. 21 05 18 21 05 36 21 06 00 Poss.a small slow flare 0.25+-0.09 1.2094 22 53 38 22 53 40 22 54 00 Small spike 0.69+-0.10 1.0281 23 52 17 23 52 18 23 52 20 Probably a narrow spike 4.09+-0.15 1.0236 Monitoring Times(U.T.) 20h18m48s- 22h57m24s There was apparently distant lightning throughout night. 22 59 36 - 23 05 18 23h36m24s- 24h00m00s 23 10 36 - 23 23 12 28th 6h53m36s 00 05 45 00 05 52 - Spike 3.60+-0.14 1.0307 - 00 06 02 00 09 06 Spike with exponential 1.36+-0.14 decay 00 41 07 00 41 09 00 41 17 Low intensity spike 0.91+-0.15 1.0648 01 27 19 01 28 09 01 32 48 Flare 1.51+-0.14 1.1507 20 02 02 20 02 19 - Spike 3.53+-0.13 1.4697 - 20 02 31 20 20 - Exponential decay 0.86+-0.13 - 20 24 - 20 26 - 20 34 - Probably a slow flare 0.13+-0.08 1.3446 20 38 03 20 38 07 20 38 28 Spike 1.99+-0.10 1.2925 Monitoring Times (U.T.) 00h00m00s - 01h01mm18s 19h54m18s- 23h20m24s 01 07 12 - 02 21 54 23 26 42 - 23 31 18 02 23 12 - 03 02 48 23 32 42 - 24 00 00 29th 7h03m30s 00 26 30 00 27 54 00 30 06 Slow flare 0.69+-0.11 1.0535 00 30 17 00 30 20 00 32 00 Spike 1.00+-0.11 1.0563 02 03 54 02 04 24 02 06 - Slow flare 0.53+-0.11 1.2740 20 31 26 20 31 28 20 31 36 Low intensity spike 0.84+-0.10 1.3036 Table (continued) ((I_0+f)-(I_0)/(I_0) Air Date Total Rise Max. Ends Comments Mass Hours (U.T.) Max. 29th 7h03m30s 20h46m58s 20h47m01s - Spike 0.75+-0.10 1.2445 - 20 47 06 20h48m48s Exponential decay 0.31+-0.10 20 49 30 20 49 40 20 51 06 Probably a slow flare 0.45+-0.10 1.2354 20 53 24 20 53 30 20 53 42 A low intensity spike 0.75+-0.12 1.2228 - 20 54 10 20 57 30 Slow flare 0.63+-0.12 1.2206 21 10 30 21 11 01 21 13 06 Flare 1.00+-0.11 1.1713 21 18 46 21 18 50 - Spike 1.73+-0.11 1.1514 - 21 18 52 21 19 55 Exponential decay 0.93+-0.11 21 25 51 21 25 54 - Spike 2.47+-0.11 1.1350 - 21 25 59 21 27 30 Exponential decay 1.33+-0.11 Monitoring Times (U.T.) 00h00m00s- 01h09m36s 19h38m24s- 20h07m24s 01 27 42 - 03 02 36(dawn) 20 09 30 - 23 16 18 19 31 06 - 19 37 00 23 22 42 - 24 00 00 30th 4h41m18s 00 08 27 00 08 44 00 09 42 Small flare 0.22+-0.11 1.0387 00 16 33 00 16 38 - Spike 2.47+-0.11 1.0458 - 00 16 45 00 19 36 Decay 1.33+-0.11 00 20 29 00 20 30 00 20 34 Narrow spike 1.28+-0.11 1.0497 00 46 48 00 46 52 - Spike 1.10+-0.11 1.0844 - 00 47 00 00 47 36 Decay 0.39+-0.11 00 31 46 01 31 51 - Spike 1.40+-0.11 1.1807 - 01 31 59 01 32 54 Decay 0.33+-0.11 01 49 27 01 99 32 01 52 12 Flare (noisy trace) 1.20+-0.19 1.2348 02 34 30 02 35 18 02 37 42 Probably a slow flare 0.29+-0.12 1.4363 21 19 29 21 14 30 21 15 00 Possibly a flare 1.00+-0.15 1.1524 22 03 41 22 03 43 22 04 30 Possibly a flare.Noisy 0.90+-0.22 1.0628 trace. 22 23 30 22 23 33 22 23 43 Spike 1.82+-0.20 1.0414 Table (continued) Air Date Total Rise Max. Ends Comments ((I_0+f)-(I_0))/(I_0) Mass Hours (U.T.) Max. Monitoring Times(U.T.) 00h00m00s- 03h02m06s 20 48 42 - 21 52 18 21 53 30 - 22 12 00 22 14 54 - 22 32 00 1st 0h47m06s No flares observed.The sky was good after clouds. Monitoring Times(U.T.) 23h09m54s- 23h25m30s 23 27 18 - 23 45 18 23 46 30 - 24 00 00 2nd 7h56m30s 00h08m43s 00h08m53s - Spike 0.92+-0.14 1.0459 - 00 08 58 00h10m30s Decay 0.37+-0.14 01 28 50 01 29 11 01 34 30 Flare 1.90+-0.12 1.1955 01 34 37 01 34 53 01 36 30 Flare 0.95+-0.11 1.2127 01 59 01 01 59 18 01 59 31 Possibly a flare 0.78+-0.10 1.3005 19 07 24 19 07 32 - Flare 0.67+-0.13 1.7728 19 08 47 19 10 00 19 16 00 Slow flare 0.72+-0.13 1.7488 22 48 35 22 98 37 22 48 57 Possibly a precursor 0.29+-0.09 1.0216 22 50 00 22 51 01 22 51 48 Probably a slow flare 0.93+-0.08 1.0209 23 54 56 23 54 58 23 55 12 Possibly a spike 0.50+-0.10 1.0370 Monitoring Times (U.T.) 00h00m00s- 03h00m00s 18 55 30 - 23 02 36 23 10 36 - 24 00 00 3rd 8h11m30s 19 11 52 19 11 53 - Narrow spike 1.57+-0.10 1.6953 19 12 02 19 12 03 19 12 15 event 1.04+-0.10 1.6938 20 40 49 20 40 56 20 41 06 Possibly a precursor 0.53+-0.10 1.2127 20 45 05 20 45 17 20 49 06 Flare 1.06+-0.08 1.1994 20 57 43 20 57 44 20 57 54 Possibly a precursor 0.63+-0.12 1.1649 Table (continued) ((I_0+f)-(I_0))/(I_0) Air Total Rise Max. Ends Comments Mass Date hours (U.T.) Max. 3rd 8h11m30s 20h58m28s 20h58m42s 21h02m12s Flare 1.74+-0.12 1.1624 21 52 22 21 52 25 - Flare 1.10+-0.09 1.0622 21 52 45 21 52 49 - Spike 1.47+-0.11 1.0617 - 21 53 01 21 54 42 Decay 0.74+-0.11 22 29 03 22 02 08 22 30 18 Maybe a small flare 0.38+-0.08 1.0286 22 34 53 22 34 53 22 35 01 Narrow spike 1.00+-0.11 1.0255 23 49 06 23 49 11 23 49 54 Flare 0.56+-0.10 1.0356 Monitoring Times (U.T.) 00h00m00s - 00h29m00s 23h06m18s- 23h29m30s 00 32 54 - 02 58 00 23 31 42 - 24 00 00 18 33 06 - 18 54 42 23 36 00 - 23 37 30 18 56 06 - 23 00 24 23 55 24 - 23 58 18 4th 3h57m48s 02h11m32s 02h11m34s 02h11m36s Possibly a narrow spike 1.69+-0.17 1.3931 02 13 13 02 13 24 02 14 24 Spike 1.25+-0.17 1.4027 18 57 03 18 57 05 18 57 24 Possibly a flare 0.54+-0.13 1.7988 19 02 24 19 02 36 - Probably weak slow 0.31+-0.12 1.7444 19 03 35 19 03 38 19 05 00 flares 0.23+-0.12 1.7346 19 05 14 19 05 16 19 06 00 Possibly a flare 0.54+-0.18 1.7195 18 10 18 19 10 48 19 27 - Possibly a slow flare 0.31+-0.13 1.6706 Monitoring Times (U.T.) 00h00m00s - 00h25m00s 00h47m24s- 01h32m00s 00 26 06 - 00 36 24 01 35 30 - 02 32 48 00 38 12 - 00 45 48 18 280 6 - 19 30 24 19 31 48 - 20 02 30 8th 5h29m24s 18 21 52 18 21 54 18 21 57 Spike 1.21+-0.18 2.0285 18 22 02 18 22 03 - Probably a spike 1.57+-0.18 2.0264 18 22 10 18 22 10 18 22 15 Probably associated with1.43+-0.18 2.0248 previous event 18 30 24 18 30 32 18 30 48 A spike-like flare 0.69+-0.14 1.9185 Table (continued) Date Total Rise Max. Ends Comments ((I_)+f)-(I_0))/(I_)) Air Hours (U.T.) Mass Max. 8th 5h29m24s 18h52m08s 18h52m11s 18h52m17s Signal scarcely 0.60+-0.17 1.6957 distinguished above noise 18 59 56 18 59 57 19 00 01 Spike 1.27+-0.15 1.6303 19 00 11 19 00 12 19 00 26 A low intensity spike 0.40+-0.15 1.6283 19 24 18 19 24 25 19 25 18 Probably a flare 0.53+-0.17 1.9612 21 11 48 21 12 00 - Possibly a spike 0.53+-0.14 1.0928 - 21 12 37 21 16 00 Possibly a slow flare 0.41+-0.14 1.0918 21 21 19 21 21 24 21 24 00 Maybe a flare 0.22+-0.10 1.0778 22 24 41 22 24 46 22 24 53 Maybe a spike 1.06+-0.13 1.0217 23 40 58 23 41 10 - Spike 0.74+-0.07 1.0457 One 23 41 19 23 41 25 - Spike 1.37+-0.09 1.0460 event 23 41 46 23 42 00 - Slow flare 0.63+-0.09 1.0466 23 42 48 23 43 42 23 59 30 Slow flare 0.44+-0.14 1.0483 Monitoring Times (U.T.) 18h19m48s- 22h40m30s 22 45 18 - 23 29 54 23 35 54 - 24 00 00 9th 7h20m42s 01 04 13 01 04 22 01 07 00 Flare 0.96+-0.13 1.2035 02 29 56 02 29 57 02 30 42 Flare 0.56+-0.12 1.6406 19 05 20 19 05 22 19 05 36 Probably a spike 0.54+-0.15 1.5596 20 41 29 20 41 30 20 41 39 Probably a spike 0.64+-0.15 1.1467 21 56 08 21 56 09 21 56 16 Probably a spike 0.56+-0.12 1.0349 23 11 26 23 11 37 - Spike 1.47+-0.11 1.0266 - 23 11 51 23 14 30 Decay 0.40+-0.11 Monitoring Times (U.T.) 00h00m00s- 01h45m42s 20h05m48s- 20h37m48s 01 49 24 - 02 41 48 20 39 00 - 21 92 18 18 10 06 - 19 13 48 21 43 30 - 22 12 18 19 15 00 - 19 29 42 22 18 18 - 22 37 18 19 39 42 - 19 59 36 22 49 12 - 22 56 18 20 00 48 - 20 04 12 23 08 12 - 23 28 18 23 49 24 - 24 00 00 Table (continued) Air Total Rise Max. Ends Comments ((I_0+f)-(I_)))/(I_o) Mass Date Hours U.T. Mass 10th 7h20m42s 01h14m22s 01h14m25s 01h18m48s 01h18m48s Flare 1.89+-0.16 1.2493 01 35 11 01 35 21 02 00 00 Flare 17.74+-0.12 1.3326 01 42 22 01 42 39 01 43 36 Slow flare(after 0.50+-0.18 1.3665 previous one) 02 10 16 02 10 18 02 11 00 Probably a flare 0.48+-0.11 1.5244 19 18 52 19 18 59 19 22 30 Probably a flare 0.35+-0.13 1.4470 19 40 20 19 40 21 19 40 28 Narrow spike 2.57+-0.18 1.3376 19 41 42 19 41 58 19 43 18 Probably a flare 0.44+-0.18 1.3304 (noisy trace) 20 32 43 20 32 57 20 33 54 Flare 0.50+-0.12 1.1579 21 26 58 21 27 07 21 28 30 Flare 0.53+-0.11 1.0594 21 21 00 21 31 13 21 33 18 Probably a flare 0.45+-0.12 1.0546 Noisy trace 8.31+-0.17 1.0525 23 39 46 23 39 48 - Spike flare 0.58+-0.09 - 23 40 11 23 47 00 Decay 23 49 55 23 49 56 23 49 58 Narrow spike 1.50+-0.12 1.0646 Monitoring Times (U.T.) 00h00m00s- 00h04m06s 18h20m00s - 18h53m42s 00 05 30 - 00 39 54 18 54 48 - 22 09 42 00 41 24 - 02 50 00 22 11 30 - 22 33 18 22 36 48 - 24 00 00 12th 4h04m48s 20 01 30 20 01 48 20 07 30 Flare 0.70+-0.17 1.2247 21 12 31 21 12 32 21 12 37 Narrow spike 1.27+-0.11 1.0680 21 56 48 21 57 04 22 01 00 Probably a slow flare 0.33+-0.13 1.0268 22 54 18 22 54 34 - Spike flare 5.33+-0.14 1.0241 - 22 55 00 23 03 00 Decay 0.57+-0.09 Monitoring Times (U.T.) 19h51m06s- 22h25m30s 22 28 36 - 24 00 00 13th 4h13m24s 00 29 00 00 29 14 00 29 39 Probably a weak spike 0.26+-0.09 1.1509 Table (continued) Max. Air Date Total Rise (U.T.) Ends Comments ((I_0+f)-(I_0))/(I_0) Mass Hours Max. 13th 4h13m24s 00h29m39s 00h30m00s 00h31m48s Probably a slow flare 0.32+-0.10 1.1528 00 34 08 00 34 12 00 36 42 Weak flare, 0.53+-0.06 1.1633 23 10 47 23 10 48 23 10 50 Possibly a precursor 1.17+-0.13 1.0363 (spike) 3.08+-0.13 1.0377 23 12 30 23 12 32 - Spike - 23 12 52 23 14 30 Decay 0.42+-0.13 Monitoring Times (U.T.) 00h00m00s - 02h04m36s 02 07 12 - 02 40 00 22 21 12 - 22 49 00 22 50 24 - 23 44 45 23 46 06 - 24 00 00 14th 5h42m36s 01 43 02 01 43 06 01 43 14 Spike 1.00+-0.14 1.4527 20 45 02 20 45 14 - Spike 12.00+-0.13 1.0984 - 20 45 20 21 02 00 Decay 6.15+-0.18 Monitoring Times (U.T.) 00h00m00s - 00h52m18s 21h28m12s- 21h32m00s 00 53 30 - 01 47 48 21 33 12 - 22 03 18 01 48 54 - 02 40 00 22 05 30 - 22 18 00 20 35 30 - 21 20 36 22 22 18 - 22 32 12 21 25 06 - 21 26 42 22 33 24 - 23 55 18