Central Bureau for Astronomical Telegrams
IAUC 4308: GX 340+0; PKS 0048-09
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Circular No. 4308
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
GX 340+0
J. van Paradijs, University of Amsterdam; W. H. G. Lewin,
Center for Space Research, Massachusetts Institute of Technology; G.
Hasinger, Max-Planck-Institute for Extraterrestrial Physics, Garching;
M. van der Klis, Space Science Department, ESTEC; W. Penninx,
Center for Space Research, M.I.T.; M. Sztajno and A. Langmeier,
Max-Planck-Institute for Extraterrestrial Physics, Garching; and F.
Jansen, Space Research Laboratory, Leiden, communicate: "EXOSAT
observations of the bright galactic-bulge x-ray source GX 340+0 (4U
1642-45), made between 1986 Apr. 6.81 and 7.30 UT, revealed the
presence of quasi-periodic oscillations (QPO) in the x-ray flux of
this source. The source countrate (1-20 keV), which varied between
about 900 and about 1300 cts/s (effective detector area about 0.14 mE2),
is positively correlated with the (6-17 keV/3-6 keV) spectral
hardness ratio ('normal' branch in the hardness-intensity diagram).
QPO were only observed when the source was relatively bright, with
countrates in excess of about 1100 cts/s (about one-third of the
observation). The power spectrum then shows a broad peak at a centroid
frequency of 5.6 +/- 0.3 Hz, with FWHM of 2.7 +/- 0.9 Hz. The
rms variation of the QPO equals 1.6 +/- 0.2 percent. The probability
of a chance occurrence of this peak is about 10E-11. Low-frequency
noise, steeply rising below 0.1 Hz, is present with an rms variation
of 1.7 percent between 0.003 and 5 Hz. When the source countrate
is below 1100 cts/s, the (2-sigma) upper limit on the rms variation
of the 5.6-Hz QPO is 1 percent. The QPO reported here are similar
to the 5.6-Hz QPO in Cyg X-2 which were also detected when the
source was on the 'normal' branch in the hardness-intensity diagram
(IAUC 4153). GX 340+0 is the tenth bright low-mass x-ray binary
known to show the QPO phenomenon."
PKS 0048-09
R. Falomo, Padua; and L. Maraschi, E. G. Tanzi, and A. Treves,
Milan, telex: "International Ultraviolet Explorer observations of
the BL-Lac object PKS 0048-09 taken at Vilspa yield fluxes of 8 (at
140 nm) and 6 (at 250 nm) x 10E-15 erg/cm**2/s/A on Jan 7.5 and
8.5, respectively. The corresponding V magnitudes from the IUE
fine-error-sensor were 14.5 (Jan. 7.4) and 14.7 (Jan. 8.6).
Observations from La Silla and Asiago (1986 Sept. 12.3, V = 16.7; Dec.
5.1, 15.1; 1987 Jan. 6.1, 15.1; 8.1, 15.4) indicate that the high
state lasted for at least one month."
1987 January 30 (4308) Daniel W. E. Green
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