Central Bureau for Astronomical Telegrams
IAUC 6426: GRS 1739-278; 4U 0614+091; CH Cyg
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Circular No. 6426
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
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)
Phone 617-495-7244/7440/7444 (for emergency use only)
GRS 1739-278
K. Dennerl and J. Greiner, Max-Planck-Institut fur
Extraterrestrische Physik, Garching, communicate: "The recent x-ray
transient GRS 1739-278 (IAUC 6350) was observed for 620 s with the
ROSAT High Resolution Imager on Mar. 31.142 UT. A bright x-ray
source with 20 counts/s was found at R.A. = 17h42m40s.3, Decl. =
-27o44'54" (equinox 2000.0; uncertainty +/- 8"), consistent with
the TTM position (uncertainty +/- 1'). The variable radio source
(Hjellming et al., IAUC 6383) is inside the ROSAT error radius,
suggesting it to be the radio counterpart. Although there is a
faint star within the x-ray error circle, it is 6" off the radio
position. Deep imaging is encouraged to identify the optical/
infrared counterpart."
4U 0614+091
E. Ford, P. Kaaret, and M. Tavani, Columbia University; B. A.
Harmon, Marshall Space Flight Center (MSFC), NASA; S. N. Zhang,
MSFC and Universities Space Research Association; and D. Barret, P.
Bloser, and J. Grindlay, Harvard-Smithsonian Center for
Astrophysics, report the detection of high-frequency,
quasiperiodic oscillations (QPOs) from the x-ray burster 4U
0614+091 with the Rossi X-ray Timing Explorer: "Using 125-
microsecond-resolution PCA data, two peaks are apparent in the
power-density spectrum with frequencies near 900 and 570 Hz. The
frequency of each peak is approximately linearly proportional to
the total countrate, varying from 750 to 950 Hz (high-frequency
peak) and 400 to 600 Hz (low-frequency peak) as the countrate
varies from 750 to 850 counts/s (full PCA). The frequency
difference between the two QPOs is constant at 327 +/- 4 Hz. The
relative widths (FWHM/nu) are constant at 15 and 6 percent,
respectively. From gaussian fits, the amplitude above the poisson
noise appears constant. A feature at 326 +/- 8 Hz with marginal
significance is present during one 30-min interval. This feature,
if confirmed, may be direct evidence for a 3.0-ms spin period of
the neutron star."
CH CYGNI
J. A. Mattei, AAVSO, reports that this symbiotic star has
faded and is now fainter than at any time on record (since 1929),
as indicated by the following AAVSO observations: May 23.1 UT,
9.4 (J. Bortle, Stormville, NY); June 6.15, 9.9 (Bortle); 15.9,
10.0 (R. Fidrich, Rakoczi, Hungary); 20.30, 10.4: (G. Hanson, Cave
Creek, AZ); 25.23, 10.3: (Hanson).
(C) Copyright 1996 CBAT
1996 June 26 (6426) Daniel W. E. Green
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