Central Bureau for Astronomical Telegrams

IAUC 6823: 4U 1630-47; SNe; 78P

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                                                 Circular No. 6823
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


4U 1630-47
     S. Dieters, University of Alabama in Huntsville; T. Belloni,
Astronomical Institute 'Anton Pannekoek', University of Amsterdam;
E. Kuulkers, Oxford University; A. Harmon, Marshall Space Flight
Center, NASA; and R. Sood, Australian Defence Force Academy,
University of New South Wales, report:  "We have analyzed RXTE/PCA
observations of the present outburst of the x-ray transient 4U
1630-47 (IAUC 6822) taken on Feb. 9.07 and 9.7 UT.  We report the
discovery of two strong quasiperiodic oscillation (QPO) peaks and
band-limited noise in the power spectrum of the 2-14-keV x-ray flux.
During our observations, the source flux (2-60 keV) was about 60
and about 140 mCrab, respectively.  The first QPO peak is
asymmetric and has centroid frequencies of 2.67 +/- 0.01 and 3.19
+/- 0.01 Hz, FWHM of 0.19 +/- 0.02 and 0.33 +/- 0.02 Hz, and
fractional rms amplitudes of 16 +/- 4 and 14 +/- 3 percent, during
the first and second observations, respectively.  The second QPO
peak has centroid frequencies of 5.59 +/- 0.07 and 6.53 +/- 0.07
Hz, FWHM of 1.2 +/- 0.2 and 1.3 +/- 0.3 Hz, and fractional rms
amplitudes of 5.5 +/- 2 and 6 +/- 2 percent, during the first and
second observations, respectively.  The second peak is most likely
a harmonic of the first.  The band-limited noise component has a
break frequency between 2 and 5 Hz and a fractional rms amplitude
of about 30 percent.  Our results indicate that 4U 1630-47 is in a
rare state (so-called very high state) seen previously only in two
other blackhole x-ray transients (GX 339-4 and GS 1124-68)."


SUPERNOVAE
     Unfiltered CCD magnitudes using GSC reference-star magnitudes
by S. Moretti and S. Tomaselli, Forli, Italy (0.35-m telescope; MT)
and by L. Boschini, Monte di Nese, Bergamo, Italy (0.25-m telescope;
B):  SN 1997dq in NGC 3810, Feb. 5.96 UT, 16.9 (MT); SN 1997ef in
UGC 4107, Feb. 5.94, 17.6 (MT).  SN 1997eg in NGC 5012, Feb. 7.15,
15.1 (B).  SN 1998A in IC 2627, Feb. 7.01, 16.7 (B).  SN 1998C in
UGC 3825, Feb. 6.86, 17.1 (B).  SN 1998D in NGC 5440, Feb. 7.17,
15.8 (B).


COMET 78P/GEHRELS 2
     Visual m_1 estimates (L = reflector):  Jan. 2.24 UT, 11.7 (R.
Keen, Mt. Thorodin, CO, 0.32-m L); 21.98, 11.4 (A. Pereira, Cabo
da Roca, Portugal, 0.25-m L); 27.83, 11.9 (K. Hornoch, Lelekovice,
Czech Republic, 0.35-m L); Feb. 1.94, 12.8 (R. J. Bouma, Groningen,
The Netherlands, 0.25-m L).

                      (C) Copyright 1998 CBAT
1998 February 12               (6823)            Daniel W. E. Green

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