Central Bureau for Astronomical Telegrams
IAUC 6063: X-RAY N IN Sco
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Circular No. 6063
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)
X-RAY NOVA IN SCORPIUS
J. Reynolds and D. Jauncey, Australia Telescope National
Facility, on behalf of the Southern Hemisphere Very Long Baseline
Interferometry (SHEVE) team, report the results of 2.3-GHz VLBI and
Parkes-Tidbinbilla Interferometer (PTI) observations of GRO
J1655-40: "Over the 7-day period Aug. 17-24, the PTI and VLBI
observations show the source to consist of a linear, highly-
collimated structure dominated by two well-separated components.
These components are moving apart at the rate of 0".095/day. At
the 3.5-kpc minimum distance implied by AT Compact Array H I
absorption observations, this corresponds to an apparent separation
velocity of 1.9c and an overall size of 11.1 light-days on Aug.
21.3 UT. The observed angular size and expansion rate point to an
origin on Aug. 15.5, which corresponds closely with the Aug. 15.2-
15.3 early maximum seen at 843 MHz (see IAUC 6062 and 6055)."
R. J. Ivison, Royal Observatory, Edinburgh; and E. I.
Robson, Joint Astronomy Centre, report: "The James Clerk Maxwell
Telescope detected the x-ray transient GRO J1655-40 on Aug. 22.3 UT
at the position reported on IAUC 6055. The 1.1- and 1.3-mm flux
densities were 0.13 +/- 0.02 and 0.13 +/- 0.03 Jy, consistent with
an extrapolation of the power law observed by the Very Large Array
on Aug. 19.1 (IAUC 6060)."
H. Inoue, F. Nagase, M. Ishida, T. Sonobe, and Y. Ueda
communicate, on behalf of the ASCA Team: "This object was observed
with ASCA during Aug. 23.47-23.93 UT. The location of the x-ray
source is R.A. = 16h53m57s.0, Decl. = -39o50'55" (equinox 2000.0),
close to the positions of the optical nova (IAUC 6050) and radio
emission (IAUC 6055), within the systematic uncertainty of the ASCA
image (error circle radius 1'). The flux in the range 1-10 keV
changed by a factor of four, starting at 80 mCrab and increasing
from 2 to 8 x 10E-9 erg cmE-2 sE-1 during the observation. No
apparent pulsation was found in the period range 1-1000 s. The
spectrum in the range below 7 keV of the low-intensity state is
represented by a power-law spectrum with photon index of about 2.1
and interstellar absorption column density of 5 x 10E21 cmE-2. An
iron absorption edge is visible at 7.1 keV. An iron emission line
around 6-7 keV and fine structures in the range 1-4 keV are
possibly seen in the spectrum. The spectrum in the high-intensity
state is similar but a little harder than that in the low-intensity
state."
1994 August 29 (6063) Daniel W. E. Green
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