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IAUC 7039: 1998el; XTE J1946+274 = 1SAX J1945.6+2721

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IAUC number

                                                 Circular No. 7039
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

     L. Germany reports the discovery by the Mount Stromlo Abell
Cluster Supernova Search Team (cf. IAUC 6639) of an apparent
supernova (V = 19.6) on V and R CCD images (limiting mag V = 20.5)
taken on Oct. 22 by M. MacDonald with the Mount Stromlo 1.27-m
telescope (+ Macho Camera).  SN 1998el is located near Abell 3122
at R.A. = 3h21m01s.21, Decl. = -41o33'06".6 (equinox 2000.0), which
is 0".9 east of the center of its host galaxy.  A nearby star has
position end figures 07s.77, 03".6.  SN 1998el was not visible on
similar images taken on Oct. 3 (limiting mag V = 20.0) but was
confirmed by M. MacDonald with the same telescope on Oct. 23
(limiting mag V = 22.0).  Finding charts are available at

XTE J1946+274 = 1SAX J1945.6+2721
     S. Campana, Brera Astronomical Observatory; G. L. Israel and
L. Stella, Rome Astronomical Observatory; and A. Santangelo,
Istituto di Fisica Cosmica e Applicazioni all'Informatica, CNR,
Palermo, report on two BeppoSAX observations performed on Oct.
4.13-4.65 and 10.94-11.53 UT of the transient 15.8-s x-ray pulsar
XTE J1946+274 (cf. IAUC 7014): "On Oct. 4 the BeppoSAX pointing was
inaccurate, and the source straddled the edge of the MECS detectors,
preventing reliable position and flux measurements.  On Oct. 10-11,
the source was observed on-axis at a flux of about 44 mCrab (1-10
keV); the position was determined to be R.A. = 19h45m38s, Decl. =
+27o21'.5 (equinox 2000.0; error radius 1' at 95-percent confidence
level).  Pulsations at periods of 15.825(1) and 15.8230(1) s were
detected during the first and second observations, respectively,
implying a spin-up of about -0.18 s/yr.  The pulse profile is
complex in the MECS (energy band 1-10 keV), and considerably
smoother in the PDS (20-100 keV), with a pulse fraction of about 26
percent.  The source was clearly detected over the range 0.5-100
keV, showing a complex continuum spectrum, with an iron line at 6.6
keV (EW = 75 eV).  The inferred column density of about 1.6 x 10E22
cmE-2 translates to A(V) about 8 magnitudes.  The Be star proposed
as the optical counterpart of the x-ray source (IAUC 7021, 7022)
lies some 10" outside the BeppoSAX error circle.  Slitless
spectroscopy obtained on Sept. 16 for the brightest (V < 15) stars
within the BeppoSAX error circle shows no evidence for H-alpha
emission lines."

                      (C) Copyright 1998 CBAT
1998 October 26                (7039)            Daniel W. E. Green

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