Central Bureau for Astronomical Telegrams
IAUC 7861: 2002bs; XTE J1908+094
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Circular No. 7861
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2002bs IN IC 4221
J. Y. Wei, Y. L. Qiu, H. L. Cao, J. Wang, and J. Y. Hu,
Beijing Astronomical Observatory (BAO), report the discovery of an
apparent supernova on unfiltered images taken with the BAO 0.6-m
telescope on Mar. 11.73 (mag about 15.5) and 23.73 UT (mag about
14.1). SN 2002bs is located at R.A. = 13h18m30s.30, Decl. =
-14o36'31".8 (equinox 2000.0), which is at the center of IC 4221.
The unfiltered image taken on Feb. 8 showed no star at the position
of the supernova. A low-dispersion spectrum taken with the BAO
2.16-m telescope on Mar. 26.67 shows that SN 2002bs is a type-Ia
supernova at about maximum brightness (V about 14.1 from the flux-
calibrated spectrum).
XTE J1908+094
M. Feroci, Istituto di Astrofisica Spaziale e Fisica Cosmica,
CNR, Rome; and L. Reboa, BeppoSAX Science Operation Center,
Telespazio, Rome, on behalf of the BeppoSAX team, report: "As a
part of the follow-up program on soft gamma-ray repeaters, BeppoSAX
serendipitously observed the new x-ray transient XTE J1908+094
(IAUC 7856). Due to technical problems with the battery system of
the spacecraft, the source was observed only with the Phoswich
Detection System (PDS) in the nominal energy range 15-300 keV. The
observation started on Mar. 9.386 UT and lasted until Mar. 12.210,
for a net observing time of about 48 000 s. Attributing all the
counts detected in the collimated field-of-view of the PDS (1.3
deg, full width at half maximum) to the new source, we can derive a
high-energy spectrum for the new x-ray transient. The source is
well detected up to > 250 keV, with a net count rate of (18.24 +/-
0.04) counts/s at 15-300 keV. The hard x-ray spectrum is not
consistent with an extension of the absorbed power law (photon
index 1.55) reported for the energy range 2-30 keV (IAUC 7856).
Instead, our data require the introduction of a high-energy cut-off
at about 100 keV (but still resulting in an unacceptable fit, with
chi**2 of about 5 per degree of freedom). Based on this model,
taking into account the 24' off-axis location of the source, we
derive a source flux of about 2.9 x 10**-9 erg cm**-2 s**-1 in the
energy range 15-100 keV. The BeppoSAX/PDS detection of the source
up to 250 keV strongly supports the interpretation of the new x-ray
transient as a new blackhole candidate."
(C) Copyright 2002 CBAT
2002 March 26 (7861) Daniel W. E. Green
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