Circular No. 3745 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758 POSSIBLE SUPERNOVA IN ESO 308-G16 J. Maza, Department of Astronomy, University of Chile, telexes that M. Wischnjewsky has found a possible supernova in the Sc galaxy ESO 308-G16 (R.A. = 6h34m0, Decl. = -39deg13', equinox 1950.0). The object is 4" east and 9" south of the galaxy's nucleus. On the discovery plate, taken on Nov. 11 by L. E. Gonzalez, the object was of photographic magnitude 16. 1E 2259+586 J. Middleditch, Los Alamos National Laboratory: and G. Fahlman, University of British Columbia, write: "Time-series data taken with the Kitt Peak 2.1-m reflector in the 350-900-nm band at five separate positions in the field of 1E 2259+586 show power at 285.51 +/- 0.04 mHz during a 1-hr run on candidate D, 2".2 south and 3".3 east of star A, the faint object mentioned by Fahlman et al. (1982, Ap. J. 261, L1). Star D is located 3" outside a 6" radius HRI error circle. Since star D is 1.5 mag fainter than A in the B band, the identical R-band relationship (Margon and Anderson, IAUC 3739) is unremarkable. However, our nearly equal Sept. RCA C31034 count rates for A and D indicate that star D is very red beyond the R band. The ~ 3-sigma pulsations correspond to B ~ 25 but could rise to 20.5 in I. The 1-mHz downshift of this observation and the previously observed 285.6-mHz pulsations (IAUC 3701), together with the weak phase modulation indicated by these observations, as well as the analysis of the recently corrected Einstein data by Fahlman and Gregory (1982, Proc. IAU Symp. No. 101), and the true fundamental pulse frequency of 143.3 mHz, are all consistent with an orbital period of ~ 2300 s. In addition, 3-hr and 6-hr sets of observations of star D in Oct. with the NASA/University of Arizona 1.5-m telescope in the 320-750-nm band did not detect 285.6-mHz pulsations but possibly detected, on one occasion, 573.2-mHz (fourth harmonic) pulsations. From this we conclude that down-shifted pulsations from star D are not apparent at wavelengths shorter than 750 nm." COMET BOWELL (1980b) Total visual magnitude estimate by J. E. Bortle, Stormville, NY (0.32-m reflector); Aug. 20.09 UT, 12.2. 1982 November 19 (3745) Brian G. Marsden
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