COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 997 Konkoly Observatory Budapest 1975 May 13 OPTICAL OBSERVATIONS OF UV CETI FLARE STARS SIMULTANEOUS WITH RADIO COVERAGE During January and February 1974, extensive radio observations of the flare stars, YZ CMi, AD Leo, Wolf 424AB, and CN Leo were obtained by Steven R. Spangler using the 1000 ft. radio telescope at Arecibo, Puerto. In this same period, simultaneous high-time-resolution optical coverage was provided at McDonald Observatory. A discussion of the flare events, observed in common at both stations, is given by Spangler and Moffett (1975). This report gives only the optical results obtained at McDonald. Since the optical coverage was incompleted, due to weather conditions, we urge other optical observers to communicate any data which they may have acquired during this observing interval. INSTRUMENTATION The optical observations were obtained with a high-speed- pulse-counting photometer attached to either the 91- or 76-cm reflector at McDonald Observatory. The basic instrument is described by Nather and Warner (1971). Due to scheduling difficulties, several different photomultiplier tubes had to be used during the course of the program (RCA 1P21, RCA 4516, Amperex 56DVP, and a FW-130). The standard PMT used in the system is the 56 DVP, which is very similar to the others used except for the FW-130, which has an S-20 photocathode. This unfortunate circumstance means that the observations are not entirely homogeneous. Since the instrumental system employing the FW-130 is not well defined, certain flare parameters have been omitted for event detected using that system. OBSERVATIONS The reduction methods and notation used are described by Moffett (1974). The four flare stars were observed for a total of 102.47 hours, during which, 119 flares were detected. Tables 1-4 give the coverage intervals together with the telescope and filter used in the monitoring. Tables 5-8 give the optical flare parameters for the flares detected on each star. The last column (Notes) states the photomultiplier in use at the time. Table 9 provides a summary of the observations. The flare frequency given is just a mean without consideration of flare amplitude, detection effects etc. The University of Texas at Austin and THOMAS J. MOFFETT McDonald Observatory References: Nather, R.E., and Warner, B. 1971, M.N.R.A.S., 152, 209 [BIBCODE 1971MNRAS.152..209N ] Moffett, T.J. 1974, Ap.J.Suppl., 29, No. 273 [BIBCODE 1974ApJS...29....1M ] Spangler, S.R., and Moffett, T.J. 1975, Ap.J., (in press) [BIBCODE 1976ApJ...203..497S ] Table 1 Coverage of YZ Canis Minoris Date (UT) From (UT) To (UT) Delta T (s) Tel. Filter (s) (cm) 1974 January 15 03 08 01 03 33 28 1527 76 U (2442062.5) 03 33 43 05 31 43 7080 76 U 1974 January 16 02 42 37 05 31 39 10142 76 U (2442063.5) 1974 January 11 02 38 11 05 31 09 10378 76 U (2442064.5) 1974 January 18 02 21 57 03 16 41 3284 76 C (2442065.5) 1974 January 20 02 12 08 02 28 32 984 76 U (2442067.5) 02 34 04 03 54 40 4836 76 U 03 56 18 05 05 52 4174 76 U 05 07 01 05 30 25 1404 76 U Table 1 (Continued) 1974 January 21 02 30 38 02 54 06 1408 76 C (2442068.5) 02 55 48 04 02 24 4176 76 U 04 05 31 05 29 33 5042 76 U 1974 January 26 02 14 50 02 27 40 707 91 C (2442073.5) 03 00 30 04 17 30 4623 91 C 04 18 30 05 03 56 2726 91 C 1974 January 28 02 47 22 03 44 32 3440 91 C (2442075.5) 03 46 10 03 51 10 306 91 C 03 52 00 05 12 10 4864 91 U 1974 January 29 02 26 44 03 59 44 5592 91 U (2442076.5) 04 00 02 05 10 22 4284 91 U 1974 January 30 02 51 45 05 34 05 9760 91 U (2442077.5) 1974 January 31 02 09 15 03 45 55 5832 91 U (2442078.5) 04 08 08 05 16 08 4254 91 U 1974 February 01 02 53 24 03 53 46 3622 91 C (2442079.5) 03 54 39 05 21 21 5202 91 C 1974 February 16 01 45 20 02 31 00 2740 91 u (S-20) (2442094.5) 02 39 19 03 21 39 2540 91 u (S-20) 1974 February 17 02 13 10 03 24 45 4295 91 v (S-20) (2442095.5) 1974 February 19 01 52 08 03 15 48 5020 91 B (S-20) (2442097.5) 1974 February 20 02 08 39 03 18 52 4213 91 B (S-20) (2442098.5) 1974 February 22 01 51 02 03 00 06 4144 91 B (S-20) (2442100.5) Table 2 Coverage of CN Leo 1974 January 27 10 05 45 10 29 39 834 91 C (2442074.5) 10 45 32 11 50 08 3876 91 C 1974 January 28 10 26 13 11 51 34 5121 91 C (2442075.5) 1974 January 30 10 05 51 11 01 08 3317 91 C (2442077.5) 11 02 39 11 32 31 1792 91 C 1974 January 31 05 32 00 06 28 10 3374 91 C (2442078.5) 06 31 41 07 42 11 4234 91 C Table 3 Coverage of AD Leonis Date (UT) From (UT) To (UT) Delta T (s) Tel. Filter (s) (cm) 1974 January 15 06 03 02 08 22 58 8396 76 U (2442062.5) 1974 January 16 05 39 57 08 31 31 10294 76 U (2442063.5) 1974 January 17 05 38 14 08 42 02 11028 76 U (2442065.5) 1974 January 18 08 05 17 08 31 39 1582 76 U (2442065.5) 1974 January 20 05 35 50 08 27 20 10290 76 U (2442067.5) 1974 January 21 05 38 38 07 41 12 7354 76 U (2442068.5) 07 41 56 08 27 22 2726 76 U 1974 January 26 05 12 58 05 58 18 2718 91 C (2442073.5) 06 02 07 06 37 07 2108 91 C 1974 January 28 05 25 00 05 46 10 1281 91 U (2442075.5) 06 01 45 06 10 15 515 91 U 1974 January 29 05 18 18 06 29 58 4336 91 U (2442076.5) 06 30 40 07 44 20 4464 91 U 1974 January 30 05 39 18 07 14 10 5692 91 U (2442077.5) 1974 February 01 05 25 11 07 39 11 8058 91 U (2442079.5) 1974 February 16 03 29 00 04 32 15 3715 91 u (S-20) (2442094.5) 04 32 47 06 03 57 5470 91 u (S-20) 1974 February 17 03 33 07 05 15 46 6159 91 v (S-20) (2442095.5) 05 16 33 06 24 43 4090 91 v (S-20) 1974 February 19 03 23 21 05 02 15 5934 91 B (S-20) (2442097.5) 05 04 51 06 11 03 4449 91 B (S-20) 1974 February 20 03 24 24 05 04 34 6010 91 C (S-20) (2442098.5) 05 07 33 05 49 43 2530 91 C (S-20) 05 50 22 06 14 04 1422 91 C (S-20) Table 4 Coverage of Wolf 424 AB Date (UT) From (UT) To (UT) Delta T (s) Tel. Filter (s) (cm) 1974 January 16 09 21 09 11 05 39 6270 76 C (2442063.5) 1974 January 17 08 55 29 09 56 35 3666 76 C (2442064.5) 09 57 15 11 07 44 4229 76 C 1974 January 18 08 38 02 11 00 53 8571 76 C (2442065.5) 1974 January 20 08 33 11 09 26 10 3179 76 C (2442067.5) 09 27 26 11 16 44 6558 76 C 1974 January 21 08 33 09 09 04 17 1868 76 C (2442068.5) 09 04 23 09 36 18 1915 76 C 09 36 56 10 20 22 2606 76 C 1974 January 29 08 10 07 08 47 47 2266 91 U (2442076.5) 08 48 11 09 49 11 3680 91 U 1974 January 30 07 56 44 09 09 44 4388 91 U (2442077.5) 09 12 11 10 00 31 2915 91 C 1974 January 31 07 48 31 10 01 54 7992 91 U (2442078.5) 1974 February 01 07 51 36 09 59 16 7820 91 C (2442079.5) 1974 February 16 06 27 23 06 44 41 1038 91 u (S-20) (2442094.5) 07 01 33 08 24 38 4985 91 u (S-20) 1974 February 17 06 40 27 07 16 17 3704 91 v (S-20) (2442095.5) 07 44 23 08 25 33 2470 91 v (S-20) 1974 February 19 06 30 07 08 16 17 6370 91 B (S-20) (2442097.5) 1974 February 22 06 10 00 07 26 00 4560 91 B (S-20) (2442100.5) 07 28 56 08 02 39 2023 91 B (S-20) Table 5 Flare Parameters for YZ CMi Flare HJD (MAX) RISE DECAY F I_max sigma/I_0 E.D. log E NOTES No. 2440000.+ (s) (s) (s) (ergs) 1 2062.71737 30 406 U 1.5 .11 73.6 30.44 1P21, spike 2 2063.64372 15 158 U 0.6 .11 19.2 29.85 56DVP, spike, double peak 3 2063.66689 136 178 U 0.5 .11 11.4 29.63 56DVP 4 2063.68955 30 99 U 0.9 .11 24.8 29.96 56DVP, spike 5 2063.71990 125 354 U 0.6 .11 45.9 30.23 56DVP 6AP 2064.69071 36 198 U 0.5 .07 5.7 29.33 56DVP, spike 6BP 2064.69474 150 627 U 0.3 .07 36.9 30.14 56DVP, slow 6C 2064.70326 31 996 U 0.9 .07 114.7 30.63 56DVP 7A 2067.63097 128 284 U 0.9 .15 71.6 30.43 56DVP 7B 2067.64130 108 102 U 0.9 .15 73.6 30.44 56DVP, double peak 7C 2067.64401 72 166 U 0.6 .15 31.4 30.07 56DVP 7D 2067.65100 278 266 U 0.6 .15 76.8 30.46 56DVP, slow 8A 2067.67554 12 20 U 1.6 .08 12.2 29.66 56DVP, spike 8B 2067.68800 447 273 U 0.4 .08 176.3 30.82 56DVP, slow 8C 2067.70545 391 213 U 0.5 .08 56.2 30.32 56DVP, slow 9 2068.63998 14 110 U 0.6 .09 9.1 29.53 56DVP, spike 10A 2068.65926 8 70 U 0.9 .09 14.2 29.72 56DVP, spike 10B 2068.66055 42 498 U 0.8 .09 53.4 30.30 56DVP 10C 2068.67292 32 250 U 0.8 .09 60.8 30.35 56DVP, multi-peak? 11AP 2068.67844 18 142 U 0.4 .08 15.9 29.77 56DVP 11B 2068.68587 120 440 U 1.8 .08 261.4 30.99 56DVP, multi-peak? 11C 2068.70205 12 144 U 2.4 .08 63.1 30.37 S6DVP, spike 11D 2068.71135 12 92 U 2.1 .08 27.9 30.02 S6DVP, spike Table 5 (Continued) 11E 2068.71552 10 16 U 0.6 .08 4.7 29.24 56DVP, spike 11F 2068.71930 51 175 U 0.4 .08 27.2 30.01 56DVP 12 2073.66493 140 93 C 0.1 .02 5.1 30.55 RCA4516 13A 2076.61319 -- 1220 U 0.5 .06 >175.2 >30.81 RCA4516, missed start 13B 2076.62752 18 738 U 0.5 .06 49.4 30.26 RCA4516 13C 2076.63768 14 110 U 0.3 .06 6.4 29.38 RCA4516 14A 2077.63530 77 649 U 0.3 .07 49.3 30.26 RCA4516 14B 2077.64319 33 745 U 0.6 .07 43.8 30.21 RCA4516, spike 14C 2077.65610 74 1496 U 0.3 .07 87.0 30.51 RCA4516 14D 2077.67441 60 212 U 0.3 .07 16.9 29.80 RCA4516 14E 2077.69200 52 960 U 0.3 .07 72.5 30.43 RCA4516 14F 2077.70334 20 938 U 0.7 .07 48.0 30.25 RCA4516, spike 14G 2077.72501 66 260 U 0.7 .07 33.0 30.9 RCA 4516, multi-peak 15AP 2078.68731 42 318 U 0.3 .06 27.8 30.01 56DVP 15B 2078.69--- -- --- U --- .06 >15.2 >29.75 56DVP, missed start 15C 2078.69400 24 886 U 0.3 .06 72.1 30.43 56DVP, slow Table 6 Flare Parameters for CN Leo FLARE HJD (MAX) RISE DECAY F I_MAX sigma/I_0 E.D. Log E NOTES No. 2440000.+ (s) (s) (s) (ergs) 1 2074.96859 6 19 C 0.9 .06 3.2 28.57 RCA4516, spike 2AP 2075.95064 6 23 C 0.6 .06 3.4 28.60 RCA4516, spike 2BP 2075.95855 22 1213 C 1.5 .06 118.4 30.14 RCA4516 2CP 2075.97280 9 207 C 1.9 .06 --- ---- RCA4516, spike 2D 2075.97526 5 --- C 3.1 .06 --- ---- RCA4516 3AP 2077.93576 23 254 C 1.8 .07 35.6 29.62 RCA4516, spike 3BP 2077.94159 5 99 C 0.4 .07 6.5 28.88 RCA4516 3CP 2077.95037 15 176 C 0.4 .07 18.0 29.32 RCA4516 3D 2077.95689 14 607 C 10.4 .07 555.9 30.81 RCA4516, double spike 4 2077.96627 -- 495 C 0.6 .07 >74.7 >29.94 RCA4516, missed start 5A 2078.80112 11 73 C 0.4 .07 8.0 28.97 56DVP 5B 2078.80436 79 194 C 0.3 .07 10.6 29.09 56DVP 5C 2078.81008 7 68 C 0.2 .07 1.7 28.29 56DVP Table 7 Flare Parameters for AD Leo FLARE HJD (MAX) RISE DECAY F I_MAX sigma/I_0 E.D. Log E NOTES No. 2440000.+ (s) (s) (s) (ergs) 1AP 2063.76555 22 855 U 0.1 .03 51.2 30.83 56DVP, slow 1B 2063.78088 33 405 U 0.5 .03 24.6 30.51 56DVP, spike 1C 2063.78652 83 334 U 0.1 .03 15.6 30.31 56DVP, slow 1D 2063.79645 124 531 U 0.3 .03 67.3 30.95 56DVP, slow 2 2063.83005 65 169 U 0.1 .03 6.6 29.94 56DVP, slow 3 2063.84715 8 178 U 0.2 .03 9.4 30.09 56DVP, flat top 4 2064.74307 214 606 U 0.2 .03 40.7 30.73 56DVP, slow 5AP 2064.78240 78 194 U 0.1 .03 7.2 29.98 56DVP, slow 5B 2064.78529 43 649 U 0.3 .03 29.7 30.59 56DVP, double peak 5CP 2064.78529 52 259 U 0.1 .03 8.0 30.02 56DVP, complex 5D 2064.82969 55 374 U 0.3 .03 19.2 30.40 56DVP, flat top 5E 2064.84529 42 320 U 0.2 .03 13.4 30.25 56DVP 5F 2064.85530 544 783 U 0.2 .03 91.0 31.08 56DVP, slow complex 6 2065.84356 14 126 U 0.1 .03 2.8 29.57 56DVP, spike 7AP 2067.80047 46 46 U 0.1 .04 2.5 29.52 56DVP 7B 2067.82239 196 484 U 1.6 .04 123.4 31.21 56DVP, double 7C 2067.83025 194 292 U 0.1 .04 26.9 30.55 56DVP, slow 8 2068.75297 6 32 U 0.1 .03 2.5 29.52 56DVP 9 2068.80027 280 1472 U 0.5 .03 122.6 31.21 56DVP, complex 10 2068.83698 58 436 U 0.1 .03 6.9 29.96 56DVP 11A 2076.79435 73 472 U 0.1 .02 16.0 30.32 RCA4516, slow 11B 2076.81294 618 1274 U 0.3 .02 86.0 31.06 RCA4516, complex slow Table 7 (Continued) 12A 2077.75529 12 1172 U 0.2 .02 22.3 30.47 RCA4516, complex 12B 2077.77330 322 1030 U 0.2 .02 28.3 30.47 RCA4516, multi-peak 13AP 2079.75807 23 216 U 0.2 .02 10.5 30.14 56DVP 13BP 2079.76897 188 1212 U 0.3 .02 41.2 30.74 56DVP 13C 2079.80221 234 1458 U 1.9 .02 507.8 31.83 56DVP, complex, 2 major peaks 14AP 2094.70272 116 476 u 4.1 -- --- ---- S-20 PMT 14B 2094.71091 232 2756 u 139.8 -- --- ---- S-20 PMT 14C 2094.74327 36 1392 u 5.0 -- --- ---- S-20 PMT 15AP 2098.67815 50 1050 C 0.3 -- --- ---- S-20 PMT 15B 2098.69348 260 2040 C 1.7 -- --- ---- S-20 PMT Table 8 Flare Parameters for Wolf 424AB FLARE HJD (MAX) RISE DECAY F I_MAX sigma/I_0 E.D. Log E NOTES No. 2440000.+ (s) (s) (s) (ergs) 1 2063.89781 9 198 C 0.2 .02 7.2 29.90 56DVP, double spike 2 2063.95943 17 206 C 0.5 .03 11.8 30.11 56DVP, spike 3AP 2064.88545 6 47 C 0.1 .03 1.0 29.04 56DVP, very small 3B 2064.88741 35 137 C 0.2 .03 6.2 29.83 56DVP, multi-peaked? 4 2064.92707 14 253 C 0.2 .03 14.9 30.21 56DVP, flat top 5 2065.91720 4 242 C 0.2 .03 7.3 29.90 56DVP, double peaked? 6A 2067.87823 3 363 C 0.3 .04 12.6 30.14 56DVP, spike 6B 2067.88680 25 35 C 0.2 .04 2.1 29.36 56DVP 7 2067.93552 10 136 C 0.7 .04 9.4 30.01 56DVP, spike 8 2067.96048 11 14 C 0.2 .04 0.6 28.82 56DVP 9 2068.87063 7 147 C 0.3 .03 4.5 29.69 56DVP, spike 10 2076.86162 54 699 U 1.1 .22 86.2 29.55 RCA4516 11 2076.88768 11 287 C 0.1 .02 5.3 29.77 RCA4516 12 2076.90780 156 156 C 0.1 .02 4.7 29.71 RCA4516, slow 13AP 2077.85407 22 148 U 0.7 .18 37.6 29.19 RCA4516 13B 2077.85671 80 704 U 2.7 .18 347.1 30.16 RCA4516, multi-peak 13C 2077.86504 16 604 U 2.3 .18 109.5 29.66 RCA4516, spike 13D 2077.87296 80 118 U 1.3 .18 17.7 28.87 RCA4516, pure spike 13E 2077.87738 12 374 U 2.0 .18 54.4 29.35 RCA4516, double spike 14 2077.89086 18 56 C 0.1 .03 1.5 29.22 RCA4516,max not well defined 15 2077.89606 5 82 C 0.1 .03 1.4 29.19 RCA4516 16 2077.89951 18 43 C 0.1 .03 1.6 29.25 RCA 4516 17 2077.91029 8 14 C 0.2 .03 0.5 28.74 RCA4516, spike 18 2078.83912 22 422 U 3.7 .20 148.9 29.79 56DVP, complex 19A 2078.86473 86 130 U 4.7 .20 85.8 29.55 56DVP, complex spike 19B 2078.86769 16 486 U 3.1 .20 177.9 29.87 56DVP, multi- -peak spike 19C 2078.90414 5 249 U 3.4 .20 152.3 29.80 56DVP, multi- -peak spike 20 2079.84103 8 56 C 0.2 .02 1.3 29.16 56DVP, spike 21 2079.88198 34 60 C 0.1 .02 2.1 29.36 56DVP 22 2079.90971 10 794 C 0.2 .02 16.0 30.25 56DVP, spike 23 2100.79879 8 10 B 0.1 -- --- --- S-20 PMT, spike 24 2100.79939 2 18 B 0.2 -- --- --- S-20 PMT, spike 25 2100.81671 - -- B 0.1 -- --- --- S-20 PMT, spike 26 2100.83659 - -- B 0.1 -- --- --- S-20 PMT, spike 27 2100.83886 - -- B 0.1 -- --- --- S-20 PMT, spike Table 9 Summary STAR COVERAGE No. OF FLARES FLARES/HR (hr) (1/hr) YZ CMi 36.83 39 1.06 AD Leo 33.53 32 0.95 Wolf 424AB 25.85 35 1.35 CN Leo 6.26 13 2.08 TOTAL 102.47 119 1.16