Central Bureau for Astronomical Telegrams
IAUC 5955: 4U 1145-619; GRS 1009-45
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Circular No. 5955
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)
4U 1145-619
R. B. Wilson, M. H. Finger, M. Stollberg, T. A. Prince, J. M.
Grunsfeld, B. A. Harmon, and S. N. Zhang report for the Compton
Gamma Ray Observatory BATSE team: "An outburst from an x-ray pulsar
is currently being observed. Pulsations were first detected on Mar.
12.5 UT. The measured barycentric pulse period was 293.4464 +/-
0.0016 s on Mar. 19.0. The location, determined on Mar. 19 using
earth-occultation mapping, is R.A. = 11h48m.6, Decl. = -62o03'
(equinox 2000.0), with an error radius of 0.2 deg. This location
is consistent with either of the transient x-ray binary systems 4U
1145-619 or 1E 1145.1-6141. Based on previously reported periods
of 292 and 297 s, respectively, the source is most likely 4U
1145-619. The period rate of change measured between Mar. 17 and
21 was (-2.43 +/- 0.34) x 10E-7. The pulse shape averaged over
Mar. 16-20 consists of a narrow peak with a phase width of about
0.35, immediately followed by a deep 'well' with a width of about
0.1 in phase. The total flux in the band 20-40 keV on Mar. 19
was 0.5 Crab. The phase-averaged pulsed flux on that day was 0.3
Crab (total). These flux values each have uncertainties of about
10 percent. The source intensity has remained within 10 percent
of these values through Mar. 21.0."
GRS 1009-45
J. Orosz, S. Barnes, and C. Bailyn, Astronomy Department, Yale
University, report: "We have observed the x-ray nova GRS 1009-45
(cf. IAUC 5864, 5890) over a period of 18 nights in February using
the Cerro Tololo Interamerican Observatory 0.9-m telescope (+ CCD
imager). Point spread function fitting was used to separate the
nova from an 18th-mag star located 1".5 to its southeast. On Feb.
7.12 UT, the nova was at V = 16.15 +/- 0.02 and B-V = +0.23.
Thereafter, the source brightness decreased at an increasing rate
until Feb. 21.62, when its magnitude was V = 18.94 +/- 0.02. The
next observation at Feb. 22.18, 163 days after the initial outburst,
showed V = 18.46, and subsequently the source continued to brighten
at a rate of about 0.02 mag/hr; by our last observation on Feb.
24.34, it had attained V = 17.43 +/- 0.02. This secondary outburst
is reminiscent of other x-ray novae, for example GRO J0422+32 (IAUC
5842, 5901, 5923). Further monitoring of this source is encouraged."
1994 March 23 (5955) Daniel W. E. Green
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