COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 538 Konkoly Observatory Budapest 1971 April 19 OBSERVATIONS OF THE FLARE STAR UV Cet DURING THE 1970 SEPTEMBER 22-OCTOBER 9 INTERNATIONAL PATROL. a) PHOTOELECTRIC OBSERVATIONS The results of UV Cet observations carried out at the Auckland Observatory, N.Z. during the 1970 campaign arranged by the I.A.U. Working Group on Flare Stars are reported. The observations were carried out in B light, except for September 22 when V filter used, with a 50 cm Cassegrain Zeiss reflector. The photomultiplier tube was an unrefrigerated EMI 9502 used with a capacitor integrating output and a digital readout. Each observation comprised one ten second integrating period. In Table 1 the detailed coverage is given together with notes on sky conditions. Table 2 lists the characteristics of the six flares observed during 13.4 hours of monitoring. In this table the columns give data as defined in IBVS 326. Flares 2, 3 and 4 are depicted in Figures 1-3, The remaining three flares are considered very doubtful. [FIGURE 1] [FIGURE 2] [FIGURE 3] Table 1 Coverage (U.T) ----------------------------------------------------------------------- 1970 Total Sky ----------------------------------------------------------------------- Sept 22 1021-1049; 1052-1100; 1108-1132 V. good between 1142-1224; 1229-1239; 1309-1320; cloudy 1334-1409; 1415-1428. 2h51m patches. 23 1108-1121; 1133-1138 0 18 Fair 29 1200-1234; 1238-1314; 1318-1331 1 23 Haze and clouds, 28 1053-1055; 1118-1131; 1137-1157 Odd 1159-1215; 1220-1252; 1301-1329; showers 1348-1401; 1406-1416. 2 14 from S.W Oct. 2 1041-1045; 1049-1054 0 09 Cloudy 3 1344-1417; 1418-1434; 1444-1446; 1450-1503; 1504-1524; 1540-1542 1 26 Poor 4 1011-1058; 1105-1149. 1 31 Cloudy; poor 7 1032-1036; 1038-1039; 1106-1117; 1124-1200; 1202-1209; 1214-1222; Passing 1224-1237; 1243-1249; 1250-1251; clouds; 1255-1256; 1258-1259; 1304-1305 1 30 Poor. 8 1052-1117; 1120-1127; 1130-1146; Inter- 1150-1216; 1217-1306 2 03 mittent cloud; poor. ---------------------------------------------------------------------- Table 2 Observed Flares -------------------------------------------------------------------- t Max(UT) Duration Integr. No. 1970 d_b d_a 3 S.D. Max. Intens. Air Notes Mins Magn. mag/min Mas Sept -------------------------------------------------------------------- 1 22 12h11.4m - - 0.045 0.16V 0.003 1.144 (1) 2 28 12 25.0 4.5 5 0.1 0.23B 0.769? 1.089 (2) 3 28 12 32.5 0.3 2.5 0.1 0.47B 0.623 1.082 Oct. 4 3 13 55.6 0.2 3.0 0.1 0.29B 0.474 1.06 5 3 14 20.6 Very doubtful because of cloud 6 8 11 24.3 Very doubtful because of cloud. ------------------------------------------------------------------- Notes: (1) Doubtful validity. May have been a recorder error. (2) Multiple activity. FRANK M. BATESON B.F. MARINO W.S.G. WALKER b) PHOTOGRAPHIC OBSERVATIONS During the 1970 campaign on UV Cet photographic monitoring was carried out with the Baker Nunn camera of the USAF Tracking Station at Mount John, N.Z. Exposure times varied and each film consisted of exposures of 3.2, 7, 15, 30 and 80 seconds. The periods covered by the monitoring are listed below together with the number of frames taken. Coverage (U.T.) --------------------------------------------- 1970 U.T. No. of Frames --------------------------------------------- Oct. 1 08h39m40s to 09h20m33s 78 1 12 06 39 12 39 29 62 4 10 42 17 11 29 28 106 4 13 50 03 14 19 39 58 --------------------------------------------- All observations were obtained under first class conditions with no cloud. A few frames could not be used through over exposure. One minor flare, estimated at 0.4m, was recorded on the frame exposed at 1970 Oct. 4 10h56m51s (U.T.). There is a suggestion that flare activity had not completely died down when the succeeding frame was exposed at 10h57m25s. FRANK M. BATESON c) VISUAL OBSERVATIONS Visual monitoring of UV Cet was carried out at the Carter Observatory, Wellington, N.Z. with the 23 cm refractor, Summary of monitoring times is given in Table 1 with notes on sky conditions, Table 2 lists possible flares observed, These should be treated with reserve unless confirmed elsewhere. Table 1 Coverage (U.T.) ------------------------------------------------------------- 1970 Total Sky ------------------------------------------------------------- Sept.22 1949-1232, 0h43m Some haze. 26 1108-1335; 1414-1514; 1550-1554; 1605-1940 4 06 Good, 27 0900-0904; 0921-1100; 1130-1230; 1245-1345; 1410-1440; 1455-1620; Cloud at 1825-1645. 5 58 times. 28 0905-1305 1330-1400; 1405-1510; 1520-1640, 6 55 Good, Oct. 7 1010-1045; 1120-1250; 1340-1440; 1450-1510, 3 25 Haze. Total 21 07 ------------------------------------------------------------- Table 2 Possible Flares ------------------------------------------ Flare Max. Duration (Minutes) Max No. 1970 (U.T.) d_b d_a Mag V ------------------------------------------ 1 Sept 22 12h15.0m 2.0 3.5 0.6 2 28 10 55.7 1.2 2.3 0.5 3 Oct 7 10 28.5 0.5 0.5 0.3 4 7 11 34.0 1.0 1.0 0.4 ------------------------------------------ VSS RASNZ 18 Pooles Road, Greerton, FRANK M. BATESON TAURANGA. D.J. CAMERON P.D. CAIN NEW ZEALAND