Central Bureau for Astronomical Telegrams
IAUC 5592: 1987A; GRO J0422+32
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Circular No. 5592
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 1987A IN THE LARGE MAGELLANIC CLOUD
P. Plait and R. Chevalier, University of Virginia; and R.
Kirshner, Center for Astrophysics, communicate: "We report the
discovery of a star near SN 1987A, superposed on the circumstellar
ring around the supernova. Images taken by the NASA Hubble Space
Telescope as part of the Supernova INtensive Study on Apr. 11 and
13, using the Planetary Camera (PC) and the ESA Faint Object Camera
(FOC), reveal a star 0".54 west and 0".50 south of the supernova
(+/- 0".02). The object is seen in continuum as well as narrow
bandpasses; the following photometry was obtained with the FOC
(175-501 nm) and the PC (547-814 nm): wavelength 175 nm, bandpass
36.4 nm, magnitude > 20.3 +/- 0.4; 275, 32.5, 21.2 +/- 0.3; 307,
34.8, 21.2 +/- 0.4; 346, 14.4, 20.3 +/- 0.3; 486, 3.7, 19.9 +/-
0.4; 501, 3.6, 19.8 +/- 0.4; 547, 18.6, 20.2 +/- 0.3; 702, 64.5,
20.5 +/- 0.3; 814, 74.7, 21.9 +/- 0.3. The instrumental magnitude
of the supernova at this epoch in the 547-nm filter was 19.3 +/-
0.2. The magnitude quoted for the 175-nm filter is a lower limit,
as the star is marginally detected above the background. The largest
contributors to the photometric error are the large background
from the ring and Stars 2 and 3, and photon statistics of the stellar
image. The magnitudes and colors of the star suggest it is an
A-type dwarf in the LMC reddened by an amount E(B-V) = 0.15. It
seems unlikely that there is a physical connection with the
supernova or the circumstellar material."
GRO J0422+32
C. Kouveliotou, University Space Research Association; M. H.
Finger, Computer Sciences Corporation; G. J. Fishman, C. A. Meegan,
and R. B. Wilson, Marshall Space Flight Center, NASA; and W. S.
Paciesas, University of Alabama at Huntsville, report for the BATSE
team: "Quasiperiodic oscillations (QPO) have been detected in the
hard x-ray flux of the x-ray transient GRO J0422+32 (IAUC 5580,
5584). The QPOs are centered at frequencies of about 0.04 and 0.2
Hz and have FWHM about 0.03 and 0.1 Hz, respectively. The power
spectrum is flat between 0.002 Hz and the first QPO, and falls as
1/f between the two QPOs. These features have been seen in 3
separate energy bands (20-60, 60-110, and 110-320 keV). The presence
of the QPO is not related to the source brightness; we are currently
searching for correlations of the QPO behavior with other source
characteristics."
1992 August 20 (5592) Daniel W. E. Green
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