Central Bureau for Astronomical Telegrams
IAUC 5578: 1992at; V1727 Cyg = 4U 2129+47; SATURN
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Read IAUC 5579
Circular No. 5578
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1992at IN ANONYMOUS GALAXY
M. Della Valle and A. Smette, European Southern Observatory,
report: "A spectrogram (range 400-840 nm, resolution about 2 nm)
was obtained with the New Technology Telescope on Aug. 7.4 UT under
poor meteorological conditions. Preliminary analysis reveals SN
1992at to be a type-Ia supernova 2-3 weeks past maximum. The
expansion velocity deduced from the minimum of the Si II 635-nm
absorption is about 9500 km/s."
V1727 CYGNI = 4U 2129+47
M. Garcia and J. Grindlay, Center for Astrophysics; and C.
Bailyn, Yale University, report: "We report the first x-ray
detection of 4U 2129+47 since it was found in a low (or off?) x-ray
state in 1983 Sept. ROSAT pointed observations taken during 1991
Dec. and 1992 Jan. find a flux of 0.75 +/- 0.14 x 10E-12 erg cmE-2
sE-1 in the 0.3- to 2.4-keV bandpass. The flux from this source
was about 100 times higher than this during the 1970s, but EXOSAT
observations in 1983 Sept. failed to detect it and set a 2-sigma
upper limit of 10E-12 erg cmE-2 sE-1 in the 0.3- to 2.4-keV bandpass.
Since then the source has been in an x-ray and optical low
(or off?) state. As the ROSAT detection and EXOSAT upper limits
are commensurate, it is not clear if the source is turning back on
or if it has been at a low flux level during the 1980s. Optical
observations are encouraged in order to measure the expected
brightening which should accompany an x-ray turn-on."
SATURN
S. J. O'Meara, Sky & Telescope; and W. Sheehan, St. Paul, MN,
write: "Using the 1-m reflector at Pic du Midi Observatory, we
have observed cloud activity at Saturn's central meridian. On Aug.
2.11 UT, the main activity followed a large, low-contrast, oval
cloud with a bright white core at System I longitude 122 deg. The
oval was nestled in the southern edge of the North Equatorial Belt
(NEB) and extended southward to the EB; swirling white clouds with
scalloped edges filled the zone following the oval between the NEB
and EB. Some thin white-cloud activity extended northward, dimming
parts of the NEB. An observation made on Aug. 1 of the region
around longitude 0 deg showed no signs of white-spot activity, and
the Equatorial Zone appeared salmon colored. On Aug. 4.05, however,
the white oval was observed with its following edge at longitude 3
deg. The white spot was confirmed by A. Dollfus."
1992 August 8 (5578) Daniel W. E. Green
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