COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 557 Konkoly Observatory Budapest 1971 May 29 PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR YZ CMi The results of photoelectric observations of the flare star YZ CMi, made through a standard B filter with the 22" reflector of the Uttar Pradesh State Observatory, Naini Tal are given, During 22, 8 hours of monitoring spread over eight nights, during the period 27 December 1970 - 24 February 1971, 3 major flares were recorded. The details are given in Table I. Excluding one observation, all others were made during the clear dark moon-periods. The light curves of the observed flares are presented in Fig. 1-3. The preliminary results showing the flare characteristics viz. time of flare maximum, duration before and after maximum, relative errors of observations, integrated intensities and air masses are drawn out, following the notations proposed by OSKANIAN (IBVS No. 488) are given in Table II. We would like to mention that a few flarelike effects that appear on the tracings have been left over at this stage, pending verification, Uttar Pradesh State Observatory Manora Peak T. R. BHATT Naini Tal, INDIA S. D. SINVHAL Table I Coverage of YZ CMi (Times are rounded to the hearest minutes of U.T.) U.T. of Coverage in hours and minutes ------------------------------------------------------------------ Date 1970. 27 Dec. 19h55m-56m, 2001-15, 2019-23, 2024-31, 2034-41, 2043-50, 2052-2100, 2102-6, 2109-15, 2117-20, 2120-26, 2127-38, 2139-42, 2143-47, 2148-51, 2204-12. 1971 17 Jan. 1647-53, 1654-57, 1711-18, 1719-25, 1726-33, 1734-36, 1846-57, 1858-1904, 1909-16, 1919-30, 1931-35, 1936-47, 1948-54, 2028-44, 2053-2107, 2122-15. 29 Jan. 1431-32, 1435-39, 1440-41, 1449-53, 1454-1506, 1507-10, 1511-15, 1517-21, 1525-43, 1544-53, 1554-1601, 1608-12, 1613-16, 1620-30, 1632-33, 1716-17, 1719-26, 1733-42, 1743-53, 1754-1801, 1805-20, 1821-22, 1827-37, 1840-53, 1901-13, 1914-20, 1927-35, 1937-53, 1954-2005, 2006-22, 2027-39, 2041-47, 2048-53, 2054-2100, 2105-17, 2120-2123. 30 Jan. 1444-51, 1454-55, 1456-59, 1502-04, 1505-07, 1508-12, 1519-25, 1526-34, 1535-41, 1542-58, 1559-1604. 31 Jan. 1431-40, 1444-1502, 1503-14, 1517-32, 1534-43, 1544-45, 1552-1608, 1608-15, 1616-24, 1625-29, 1634-43, 1644-52, 1653-58, 1748-1804, 1805-09, 1813-24, 1825-41, 1842-51, 1852-1904, 1905-07, 1909-16, 1918-32, 1933-47, 1949-50, 1953-2011; 2012-17, 2019-31, 2033-41, 2046-58, 1059-2108 2118-25, 2128-31. 2 Feb, 1417-20, 1431-34, 1439-44, 1445-57, 1458-1504, 1505-13, 1514-26, 1527-33, 1534-40. 23 Feb. 1633-35, 1636-42, 1709-10, 1711-23, 1725-41, 1743-1801, 1803-22, 1824-41, 1848-49, 1850-58, 1859-1911, 1913-29, 1930-38, 1939-46, 1951-56. 24 Feb. 1417-18, 1420-37, 1439-41, 1446-47, 1449-52, 1453-1501, 1502-05, 1506-20, 1522-32, 1533-36, 1537-40, 1541-48, 1549-1610, 1611-12, 1613-28, 1630-39, 1639-46, 1648-56, 1657-1707, 1709-27; 1728-33, 1734-42, 1743-45, 1747-49, 1751-55, 1756-1802, 1804-20, 1821-36, 1838-44, 1845-55, 1857-1909, 1929-36, 1939-49, 1950-2008, 2010-20, 2021-32, 2033-36, 2037-38. --------------------------------------------------------------- Table II Flares of YZ CMi Observed at Uttar Pradesh State Observatory, Naini Tal 27 December 1970 - 24 February 1971 ----------------------------------------------------------------- Duration of flare before Date UT_max and after X_fm/X-s maximum sigma/X_s t_b t_a P Minutes F(z) ----------------------------------------------------------------- 1970 27 Dec. 20h08m52s 1.33 50.11 2.24 0.026 8.30 1.11 1971 29 Jan. 15h35m30s 0.38 12.75 0.51 0.040 1.78 1.33 24 Feb. 19 31 21 0.35 2.35 0.45 0.013 0.31 1.71 ----------------------------------------------------------------- [FIGURE 1] [FIGURE 2] [FIGURE 3]