Circular No. 5526 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Telephone 617-495-7244/7440/7444 (for emergency use only) TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505 MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU) PROBABLE NOVA IN SCORPIUS Paul Camilleri, Cobram, Victoria, reports his discovery of what appears to be a nova at R.A. = 17h03m.9, Decl. = -43 12' (equinox 1950.0). The following magnitude estimates are by Camilleri unless otherwise noted, and all are photovisual except for those on May 24 (which are visual): Apr. 28.600 UT, [12; May 22.492, 8.2; 23.511, 8.3; 24.371, 8.3 (P. Williams, Heathcote, N.S.W.); 24.425, 8.4. NOVA CYGNI 1992 G. M. Hurst, The Astronomer, reports that inspection of 0.5- day means of visual data of Nova Cyg 1992 taken by The Astronomer Group are suggestive of an about 2.5- or 5-day periodicity postmaximum. Subsequent periodicity analysis by M. Kidger (Instituto de Astrofisica de Canarias), using the Jurkevich method, of > 400 visual data points in The Astronomer Group archive supports a 4.7- day period with regular minima of amplitude 0.3 mag, and Kidger notes: "There is also some evidence of a possible intermediate shallow secondary minimum. Analysis of all available V-band photometric data from IAUCs, The Astronomer Group, and Agrupacion Astronomica de Tenerife shows regular oscillations in the light curve until late April. Periodicity analysis gives a best period of 4.6 +/- 0.2 days. There are insufficient data to define the mean light curve form, but the photometric amplitude agrees with that from the visual data. These oscillations are similar to those of V1668 Cyg = N Cyg 1978 (Campolonghi et al. 1980, A.Ap. 85, L4), but are considerably slower. No obvious color variations are seen with this period. Since t3, which was 47 days, the oscillations have apparently disappeared." Photometry by B. Dintinjana and H. Mikuz obtained with the 0.25-m Schmidt-Cassegrain telescope (+ CCD) at the the University of Ljubljana Astronomical Observatory: May 9.103 UT, V = 8.46 +/- 0.01, B-V = -0.34 +/- 0.03, V-R = +1.21 +/- 0.02 (comparison star HR 7730); May 14.083, 8.43, -0.35, +1.10 (comparison star HD 195664). Further visual magnitude estimates: May 6.40 UT, 8.4 (G. W. Kronk, Troy, IL); 13.88, 8.0 (E. Schweitzer, Strasbourg, France); 16.99, 8.3 (B. H. Granslo, Fjellhamar, Norway); 20.96, 8.3 (Granslo); 23.19, 8.4 (W. G. Dillon, Missouri City, TX); 24.46, 8.4 (A. Jones, Nelson, N.Z.). 1992 May 24 (5526) Daniel W. E. Green
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