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IAUC 5504: 4U 1543-47; CH Cyg; HV Vir

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                                                  Circular No. 5504
Central Bureau for Astronomical Telegrams
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

4U 1543-47
     B. A. Harmon, R. B. Wilson, M. H. Finger, W. S. Paciesas, B. C.
Rubin and G. J. Fishman, NASA Marshall Space Flight Center, report, on
behalf of the BATSE-Compton Gamma Ray Observatory Experiment Team:
"Beginning Apr. 18, hard x-ray flux has been detected using earth
occultation at a location consistent (within 0.25 deg) with the
position of the recurrent x-ray nova 4U 1543-47 (IAUC 3854, 3858).
The flux increased over a three-day period to an apparent maximum on
Apr. 20, where the one-day average flux level relative to the Crab
Nebula in the energy bands 20-50, 50-120 and 120-230 keV was
1.08 +/- 0.02, 0.54 +/- 0.02 and 0.29 +/- 0.04, respectively.  Single
power-law fits to the photon spectrum yielded spectral indices of 2.2
+/- 0.1, 2.9 +/-0.1 and 2.9 +/- 0.1 on Apr. 19, 20 and 21.  Monitoring
of the source for changes in intensity and spectral characteristics is
continuing. Observations at other wavelengths are encouraged."

     A. Skopal, L. Hric and R. Komzik, Astronomical Institute of the
Slovak Academy of Sciences, Skalnate Pleso Observatory, communicate:
"There has been a sudden increase in the activity of the symbiotic
star CH Cyg.  A spectrogram (range 360-490 nm, dispersion 1.7 nm/mm)
was obtained with the Czechoslovak Academy of Sciences' 2-m telescope
at the Ondrejov Observatory on Apr. 12.08 UT.  The spectrum shows
strong emissions of H I, He I, Ca II H and K, Fe II, [Fe II] and [S
II].  The Ca I 422.7-nm line is very weak and broad.  The Balmer lines
are seen up to H27.  Ca II H and K, as well as the hydrogen lines,
exhibit a P-Cyg profile.  Weak absorption components of Ti II 444.4,
450.1 and 453.4 nm are also present.  Photoelectric photometry carried
out at Skalnate Pleso indicate a recent increase in the star's
brightness, particularly in U and B: 1991 Nov. 12.88 UT, V = 8.730, B
= 10.704, U = 11.704; Dec. 12.79, 8.696, 10.434, 10.854; 1992 Mar.
10.04, 8.430, 9.308, 8.696; Apr. 18.96, 8.631, 9.399, 8.411."

     Visual magnitude estimates: Apr. 22.89 UT, 11.7 (H. Dahle, Oslo,
Norway); 23.02, 11.8 (B. H. Granslo, Fjellhamar, Norway); 23.85, 12.5
(M. Verdenet, Bourbon-Lancy, France); 23.88, 12.4 (Dahle); 23.90, 12.0

1992 April 24                  (5504)              Brian G. Marsden

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