Central Bureau for Astronomical Telegrams
IAUC 6419: X-RAY TRANSIENT IN THE LMC; ROSAT SOFT-X-RAY MAPS
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Circular No. 6419
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)
X-RAY TRANSIENT IN THE LARGE MAGELLANIC CLOUD
F. E. Marshall, Laboratory for High Energy Astrophysics,
Goddard Space Flight Center (LHEA/GSFC); and R. Corbet and T.
Strohmayer, Universities Space Research Association and LHEA/GSFC,
report the discovery of a new hard-x-ray source in the direction of
the LMC using the RXTE's Proportional Counter Array. The 2- to 10-
keV flux on June 8.19 and 11.31 UT was about 18 mCrab (luminosity
1.3 x 10E38 erg/s at the distance of the LMC). The best-fit
position is R.A. = 5h22m.5 +/- 0m.2, Decl. = -69o37' +/- 9'
(equinox 2000.0). An absorption event on June 11.3154 lasting
about 100 s suggests a high-inclination binary system. No
pulsations were seen, with an upper limit on the pulsed fraction of
1 percent for frequencies between 0.1 and 40 Hz. Additional x-ray
observations are urged to establish an accurate position and
possibly to determine a binary period.
ROSAT SOFT-X-RAY MAPS
S. L. Snowden, M. J. Freyberg, P. P. Plucinsky, J. H. M. M.
Schmitt, J. Trumper, and W. Voges, Max-Planck-Institut fur
Extraterrestrische Physik, Garching; R. J. Edgar, D. McCammon, and
W. T. Sanders, University of Wisconsin, Madison, report: "The
first maps of the soft x-ray diffuse background (SXRB) from the
ROSAT XRT/PSPC All-Sky Survey have been released and are available
through the World Wide Web (URL http://www.rosat.mpe-
garching.mpg.de/survey/sxrb/) and via anonymous ftp (host
ftp.rosat.mpe-garching.mpg.de, directory archive/survey/sxrb). A
detailed description of the data and maps has appeared in Ap.J.
454, 643 (1995). The maps cover about 98 percent of the sky in
the bands 0.25, 0.75, and 1.5 keV, with about 2-degree angular
resolution and high sensitivity for low-surface-brightness,
extended features. The effects of non-x-ray contamination and x-
rays of solar-system origin have been eliminated to the greatest
possible extent, but discrete x-ray sources have not been removed.
The much-improved angular resolution, statistical precision, and
completeness of coverage of these maps reveal considerable
structure over the entire energy range 0.1-2.0 keV that was not
observed previously. The data compare well with previous all-sky
surveys in terms of absolute normalization and zero point. For
each energy band, an intensity map, as well as an exposure map, is
available in FITS format. All maps were constructed using a
Hammer-Aitoff equal-area projection in zero-centered galactic
coordinates with longitude increasing to the left. Questions or
comments may be directed to sxrb@rosat.mpe-garching.mpg.de."
(C) Copyright 1996 CBAT
1996 June 17 (6419) Daniel W. E. Green
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