Central Bureau for Astronomical Telegrams
IAUC 7710: 2001ef; XTE J1650-500
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Circular No. 7710
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2001ef IN IC 381
G. M. Hurst, Basingstoke, England, reports the discovery by M.
Armstrong (Rolvenden, England) of an apparent supernova (mag 16.1)
on unfiltered CCD images taken on Sept. 9.066 and 9.160 UT in the
course of the U.K. Nova/Supernova Patrol with a 0.36-m Schmidt-
Cassegrain telescope. An image by Armstrong on Sept. 9.907 yields
mag 16.0; a confirming image was also obtained by N. James
(Chelmsford, England) on Sept. 9.900. SN 2001ef is located at R.A.
= 4h44m28s.56, Decl. = +75o38'30".3 (equinox 2000.0; average of
three measures), which is 1" east and 8" north of the center of IC
381. Nothing appears at this location on images taken by Armstrong
on 2000 Oct. 9 (limiting mag 19.5) and 2001 Aug. 17 and 29; nothing
is visible on second Palomar Sky Survey images taken on 1995 May 19
(blue, limiting mag 22.5), 1996 Dec. 8 (red, limiting mag 20.8),
and 1997 July 19 (infrared). Hurst adds that nothing is present at
this position in an image in J. C. Vickers' Deep Space CCD Atlas
North (1993, p. 44; limiting mag about 19.5). A. Miceli, C. Stubbs,
and C. Hastings find the new object to be 0".33 east and 7".3 north
of the galaxy's center; their preliminary photometry with the
Apache Point 3.5-m telescope on Sept. 10.44 yields u' about 17.5,
g' about 17.3, r' about 16.5, i' about 16.9, z' about 16.1.
XTE J1650-500
T. Augusteijn, Isaac Newton Group of Telescopes, La Palma; M.
Coe, University of Southampton; and P. Groot, Harvard-Smithsonian
Center for Astrophysics, report: "Spectroscopic observations (range
390-760 nm; resolution 0.7 nm) of the proposed optical counterpart
of the x-ray transient XTE J1650-500 (cf. IAUC 7707, 7708) were
made on Sept. 8.74 UT with the 1.9-m telescope at the South African
Astronomical Observatory. The observations were made through
varying cloud cover, and are not flux-calibrated. The spectrum
shows emission lines from the Balmer series, which are unresolved
and have equivalent width (EW) 0.2-0.4 nm. This confirms the
identification of the source as an (soft-x-ray-type) low-mass x-ray
binary in outburst. Also detected are several interstellar
absorption features. From the EW of 0.20 +/- 0.02 nm obtained for
the diffuse interstellar band at 628.3 nm, we estimate an E(B-V)
about 1.5 mag. Assuming that it is at the distance of the Galactic
center, we derive an absolute visual magnitude of -2 for the
source. This implies that the source is likely a long-orbital-
period system, as is also indicated by the apparent small outburst
amplitude."
(C) Copyright 2001 CBAT
2001 September 10 (7710) Daniel W. E. Green
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