COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1018 Konkoly Observatory Budapest 1975 July 7 FLARE PHOTOMETRY OF YZ CANIS MINORIS During January 1975 the flare star YZ Canis Minoris [R.A.= 7h42m, declination=3d39' (1968.0), visual magnitude 11.6] was monitored at Boyden Observatory for a total time of 30h02m54s. The telescope used in this work was the 41 cm Nishimura Reflector fitted with a Johnson B filter. An uncooled EMI6256A photomultiplier tube was used as a detector. From the following table it will be seen that there was one major flare and one minor flare. Other small flares are marked as questionable due to poor observing conditions with an ensuing noisy signal. The flare of (I_0+f - I_0)/I_0 value = 9.06 at 22h49m35s on the night of 10-11th January was confirmed visually. 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 YZ CMi - JANUARY 1975 ----------------------------------------------------------------------------------------------------------------- Total Max. Air Date hours Rise U.T. Ends Comments (I_o+f - I_o)/I-o mass Max. ----------------------------------------------------------------------------------------------------------------- 03-04 3h18m00s No flares Monitoring Times: 22h43m46s - 22h47m48s U.T. 23 56 30 - 02 10 18 ----------------------------------------------------------------------------------------------------------------- 04-05 3h46m48s No flares Monitoring Times: 22h21m00s - 23h53m30s discernable above U.T. 23 59 30 - 02 13 48 noisy level ----------------------------------------------------------------------------------------------------------------- 05-06 2h45m24s 01h11m44s 01h11m48s 01h13m42s Flare? Moonlit 0.21+-0.10 1.4304 Monitoring Times: 23h23m12s - 00h24m00s and some U.T. 00 31 00 - 02 15 48 clouds ----------------------------------------------------------------------------------------------------------------- 08-09 1h43m30s 00h41m48s 00h42m06s 00h43m18s Slow flare? 0.26+-0.12 1.3615 Moonlit high cloud present ----------------------------------------------------------------------------------------- 00 53 06 00 53 30 00 56 30 Flare. Moonlit 0.32+-0.11 1.4035 high cloud resent ----------------------------------------------------------------------------------------- Monitoring Time: 00h33m12s- 02h16m42s U.T. ----------------------------------------------------------------------------------------------------------------- 09-10 3h02m54s 22h48m24s 22h48m54s 22h51m00s Could be a slow 0.17+-0.14 1.1857 flare but noisy signal --------------------------------------------------------------------------------------------- 23 02 24 23 02 42 23 04 00 Could be a slow 0.1+-0.1 1.1900 small flare but very doubtful. --------------------------------------------------------------------------------------------- Monitoring Times: 22h20m30s - 00h07m24s U.T. 00 12 36 - 00 47 12 00 56 48 - 02 18 12 ----------------------------------------------------------------------------------------------------------------- 10-11 3h56m54s 22h47m54s 22h149m35s 00h54m00s Flare visually 9.06+-0.19 1.1866 confirmed --------------------------------------------------------------------------------------------- Monitoring Times: 22h18m48s - 01h06m54s U.T. 01 12 06 - 02 20 54 ----------------------------------------------------------------------------------------------------------------- 11-12 4h00m18s 00h02m36s 00h02m58s 00h18m30s Flare 1.11+-0.12 1.2925 --------------------------------------------------------------------------------------------- Monitoring Times: 22h14m36s - 22h44m00s U.T. 22 48 12 - 02 19 06 ----------------------------------------------------------------------------------------------------------------- 12-13 3h19m00s 23h49m18s 23h49m25s 23h49m42s Possibly a 0.18+-0.07 1.2618 Monitoring Times: 22h14m24s - 22h47m06s small flare, U.T. 22 53 48 - 01 40 06 preceeded by a slight dip in trace ----------------------------------------------------------------------------------------------------------------- 16-17 4h10m06s Nothing clearly Monitoring Time: 22h14m30s - 02h24m24s greater than noise U.T. and sky variations Atmosphere was dusty