Circular No. 4606 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 617-495-7244/7440/7444 MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN ASM 2000+25 R. Sunyaev and the Kvant Team, Space Research Institute, U.S.S.R. Academy of Sciences, report: "The MIR-Kvant Rontgen Observatory detected this x-ray nova on May 15 and 17 in the spectral band 4-250 keV. The Pulsar X1 Phoswich device discovered a hard power-law x-ray tail in the spectral band 20-250 keV with flux 0.5 E**-1.7 photons cm**-2 s**-1 keV**-1, where E is the photon energy measured in keV. The Hexe device discovered the same tail in the band 15-150 KeV. On May 17 the GSPC device detected the soft component of the spectrum in the band 4-15 keV. For a thermal bremsstrahlung model the best fit gives a plasma temperature of 1.86 +/- 0.05 keV. The soft component, which was reported earlier by the Ginga Team, corresponds to a luminosity of 3 x 10**36 erg/s for a distance of 1 kpc; the luminosity of the hard component is three times smaller. These values refer only to to the spectral bands mentioned above." PERIODIC COMET SCHWASSMANN-WACHMANN 1 J. Gibson reports that his observations with the 1.5-m reflector (+CCD and Gunn R filter) at Palomar on May 27.44 UT showed this comet to be in outburst at m1 about 14.4. There was a coma of diameter 25" and a tail 10" long in p.a. 190 deg. PERIODIC COMET GUNN Total visual magnitude estimate by D. Levy, Mt. Lemmon, AZ (1.5-m reflector): May 7.24 UT, 14.6 (coma diffuse with slight condensation). PERIODIC COMET TEMPEL 2 (1987g) Total visual magnitude estimates by E. A. Jacobson, Evansville, MN (0.25-m reflector): May 24.35 UT, 13: (suspected); 26.38, 13.2 (confirmed with 0.29-m reflector at m1 = 13.3). COMET LILLER (1988a) Total visual magnitude estimates: May 22.92, 6.3 (A. Pereira, Linda-a-Velha, Portugal, 9 x 34 binoculars); 24.17, 6.6 (Jacobson, 10 x 50 binoculars; in moonlight); 27.96, 6.7 (Pereira, 0.15-m reflector); 30.87, 6.9 (S. Baroni, Milan, Italy, 20 x 80 binoculars). 1988 June 2 (4606) Brian G. Marsden
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