COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 736 Konkoly Observatory Budapest 1972 November 8 OBSERVATIONS OF UV CETI DURING THE 1972 OCTOBER 1-15 INTERNATIONAL PATROL During part of the International Patrol of 1972 October, UV Ceti was observed for a total of 26.5 hours resulting in 50 detected flare events. All photoelectric observations were obtained on the 76-cm reflector at McDonald Observatory. A few time-resolved spectroscopic observations were also obtained by B. W. Bopp on the 208-cm Struve reflector at McDonald Observatory. This report is only preliminary. A complete discussion of these observations will be published at a later date. INSTRUMENTATION The photoelectric observations were obtained with a high speed pulse counting photometer using a specially selected Amperex 56 DVP photomultiplier tube operated uncooled. The basic instrument is described by Nather and Warner 1971 (1). In most cases, no filter (NF) was used in order to study very rapid variations during flare events (2). With no filter employed, the band-pass of the system is defined by the spectral response of the Amperex 56 DVP. The photocathode is a bialkali type D which has a maximum response (25% Q.E.) at 4000 A, and half response points at 3100 and 5200 A. When using integration times of less than one second, the data is stored in the computer's memory (8K). Approximately two hours are required to dump the memory onto paper tape and, for this reason, some flares were observed for which the data was not saved. These flares are indicated by (*) in Table 2. OBSERVATIONS Table 1 gives the exact times (UT) of the observations. Sky readings are included in these intervals but since a sky measurement required only 10 seconds the coverage can be considered almost complete over any time interval. Table 2 gives preliminary values of some flare characteristics of the observed events. Columns 3 and 4 give the heliocentric Julian date and Universal Time (with heliocentric time correction included) of the peak intensities. Approximate heliocentric time corrections for UV Ceti are given below: ----------------- 72 OCT 10 +447s 72 OCT 11 +446s 72 OCT 13 +445s 72 OCT 14 +444s 72 OCT 15 +443s ----------------- Column 5 contains the maximum flare intensity defined by: I_max = ((I_0 +I_flare) / I_0) - 1 where I_0 is the intensity of the star a short time before the onset of the flare. Column 6 was included to conform to suggestions made by the IAU Working Group on Flare Stars 93). It should be noted that for pulse counting observations, this term (3sigma/I_0) overestimates the error associated with the peak intensity since it does not take into account that the photon noise is a function of the count rate. Column 7 is the total relative energy (R.E.) of the flare event. The unit of relative energy is the amount of energy radiated by the quiescent star in the stated bandpass in one second. The integration time (IT) is stated in column 8. The University of Texas at Austin T. J. MOFFETT and B. W. BOPP McDonald Observatory October 30, 1972 REFERENCES (1) Nather, R.E., and Warner, B. 1971, M.N.R.A.S., 152, 209. [BIBCODE 1971MNRAS.152..209N ] (2) Moffett, T.J. 1972, Nature (in press). (3) Chugainov, P.F. 1971, IBVS No. 605. TABLE 1 COVERAGE OF UV CETI ------------------------------------------------ UT DATE FROM(UT) TO(UT) DeltaT(s) ------------------------------------------------ 72 OCT 10 05 46 30 06 21 00 2070 06 25 36 07 09 53 2657 07 11 15 07 42 56 1901 07 43 07 08 17 03 2036 08 17 11 08 47 12 1801 08 48 13 09 22 11 2038 72 OCT 11 03 58 00 04 34 15 2175 04 37 44 05 07 56 1812 05 08 05 05 38 07 1802 05 38 16 06 08 18 1802 06 08 25 06 31 26 1381 06 37 30 07 07 31 1801 07 07 40 07 37 41 1801 07 37 48 08 07 51 1803 08 08 00 08 47 30 2370 08 48 12 09 14 59 1607 09 16 03 09 37 44 1301 72 OCT 12 03 55 57 04 50 12 3255 08 04 00 09 48 00 6240 72 OCT 13 03 23 00 03 26 00 180 03 30 16 04 31 06 3650 04 31 50 05 01 50 1800 05 02 01 05 32 01 1800 05 34 00 06 12 35 2315 06 17 38 06 47 38 1800 06 48 16 07 18 16 1800 07 18 46 07 48 46 1800 07 48 53 08 18 53 1800 08 20 01 08 50 01 1800 08 50 07 09 20 07 1800 09 20 14 09 50 14 1800 72 OCT 14 03 25 02 03 55 02 1800 03 55 12 04 25 12 1800 04 25 18 05 09 46 2068 05 22 00 06 52 30 5430 06 56 42 07 26 59 1817 07 31 27 08 04 54 2007 08 05 04 08 39 30 2066 08 39 39 09 27 59 2900 72 OCT 15 03 47 14 04 27 17 2403 04 27 26 04 58 21 1855 05 00 07 05 30 16 1809 05 38 00 07 15 00 5407 --------------------------------------------- SUMMARY -------------------------------------------------------- UT DATE TOTAL TIME(s) TOTAL TIME(hr,min,s) -------------------------------------------------------- 72 OCT 10 12503 03 28 23 72 OCT 11 19655 05 27 35 72 OCT 12 9495 02 38 15 72 OCT 13 22345 06 12 25 72 OCT 14 19888 05 31 28 72 OCT 15 11474 03 11 14 -------------------------------------------------------- TABLE 2 Flare Characteristics UV CETI -------------------------------------------------------------------------------- FLARE JD_Hel (UT)_Hel I_max 3sigma/I_0 R.E. IT F NO. UT Date 2441600.+ -------------------------------------------------------------------------------- 1 72OCT10 0.748596 5 57 58.7 .86 .15 4.35 0.25 NF 2 0.790763 6 58 41.9 .14 .08 5.56 1.00 NF 3 0.797916 7 85 9.9 .27 .08 2.13 1.00 NF 4(1) 0.798958 7 10 30.0 .17 .08 1.00 NF 5(1) 0.799085 7 10 40.9 .14 .08 12.51 1.00 NF 6(1) 0.799236 7 10 54.0 .38 .08 1.00 NF 7 0.857453 8 34 43.9 .51 .07 6.73 1.00 NF 8 0.861990 8 41 15.9 .14 .07 0.41 1.00 NF 9 0.866446 8 47 40.9 .58 .07 9.51 1.00 NF 10 0.877476 9 33 3.9 1.08 .09 23.23 1.00 NF 11 0.892916 9 25 47.9 .18 .09 3.31 1.00 NF 12 72OCT11 1.674280 4 10 57.8 .29 .21 2.44 0.25 NF 13 1.681595 4 21 29.8 1.81 .21 22.55 0.25 NF 14 1.701731 4 50 29.6 .17 .09 6.43 1.00 NF 15 1.713259 5 7 5.6 .31 .09 7.70 1.00 NF 16 1.758108 6 11 40.5 .13 .10 1.12 1.00 NF 17 1.764983 6 21 34.5 .26 .09 4.35 1.00 NF 18 1.772448 6 32 19.5 .15 .09 4.80 1.00 NF 19 1.791626 6 59 56.5 .23 .09 18.81 1.00 NF 20 1.802726 7 15 55.5 .95 .09 5.81 1.00 NF 21 1.857818 8 35 15.5 .73 .09 90.10 1.00 NF 22 1.865028 8 45 38.4 .24 .09 6.36 1.00 NF 23 1.866568 8 47 51.5 .47 .09 59.64 1.00 NF 24 1.875353 9 00 30.5 .57 .09 10.03 1.00 NF 25 1.878952 9 54 1.5 .22 .09 9.20 1.00 NF 26 1.885654 9 15 20.5 .21 .09 13.10 1.00 NF 27 1.887656 9 18 13.5 2.73 .09 39.33 1.00 NF 28 72OCT13 3.742235 5 48 49.1 .52 .19 21.81 0.25 NF 29 3.747246 5 56 2.1 .52 .19 15.69 0.25 NF 30 3.818568 7 38 44.3 .22 .10 2.13 1.00 NF 31 3.839285 8 83 4.2 .16 .09 4.63 1.00 NF 32 3.856970 8 34 2.2 1.19 .10 58.05 1.00 NF 33 3.858105 8 35 40.3 2.91 .10 306.59 1.00 NF 34 3.873706 8 58 8.2 1.37 .10 25.25 1.00 NF 35 3.898022 9 33 9.1 .42 .11 24.37 1.00 NF 36 72OCT14 4.700006 4 48 0.5 .21 .09 4.86 1.00 NF 37* 4.734371 5 37 24.5 -- -- -- 0.25 NF 38 4,771767 6 31 20.7 1.43 .16 40.24 0.25 NF 39 4.776767 6 38 32.7 .40 .16 5.80 0.25 NF 40(2) 4.823257 7 45 29.4 3.39 .81 450.59 1.00 U 41(2) 4.859380 8 37 30.4 8.15 .70 606.99 1.00 U 42(2) 4.868407 8 50 30.4 127.11 .78 5068.99 1.00 U 43(2) 4.892006 9 24 29.3 1.74 .78 51.51 1.00 U 44 4.894148 9 27 34.4 1.37 .78 119.26 1.00 U 45* 72OCT15 5.750561 6 00 48.0 -- -- -- 0.25 NF 46*(2) 5.759994 6 14 23.0 -- -- -- 0.25 NF 47*(2) 5.766938 6 24 00.0 -- -- -- 0.25 NF 48*(2) 5.771452 6 30 53.0 -- -- -- 0.25 NF 49*(2) 5.778917 6 41 38.0 -- -- -- 0.25 NF 50*(2) 5.800271 7 12 23.0 -- -- -- 0.25 NF ------------------------------------------------------------------------------- NOTES: (1) FLARE No. 4, 5 and 6 are included in the relative energy of No. 5 (2) Spectra (*) ORIGINAL DATA NOT SAVED. SMALL FLARE I_max < 0.2.