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IAUC 6932: XTE J1748-288; XTE J2012+381

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                                                 Circular No. 6932
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


XTE J1748-288
     D. A. Smith, A. Levine, and A. Wood, Massachusetts Institute
of Technology (MIT), report for the RXTE ASM team at MIT and NASA
Goddard Space Flight Center: "The RXTE All-Sky Monitor has detected
a transient x-ray source at R.A. = 17h48m08s, Decl. = -28o28'.8
(equinox 2000.0; error radius 5', to better than 90-percent
confidence).  The source was observed in each of two detector
systems in two contiguous 90-s exposures on June 4.69 UT, and again
in two more observations 1.8 hr later.  The spectrum is hard, with
typical fluxes of 90, 300, and 470 mCrab in the bands 1.5-3, 3-5,
and 5-12 keV, respectively."


XTE J2012+381
     R. I. Hynes and P. Roche, University of Sussex, report:
"Images were taken with the 1.0-m Jacobus Kapteyn Telescope, La
Palma, on June 3.14-3.23 UT by N. Walton (Isaac Newton Group) of
USNO 1275.13846761 (A1.0 catalogue position R.A. = 20h12m37s.80,
Decl. = +38o11'00".6, equinox 2000.0), a possible optical
counterpart (IAUC 6931) to XTE J2012+381 (IAUC 6920).  We estimate
U = 19.4, B = 19.1, V = 17.9, R = 17.2, I = 16.6 (+/- 0.2 mag).  V,
R, and I images also show a faint red companion star 1".2 away; we
measure an offset in R.A. of -0s.09 +/- 0s.01, and in Decl. of
+0".5 +/- 0".1 (i.e., position end figures 37s.71, 01".1).  We
estimate V = 21.3, R = 20.1, I = 18.6 (+/- 0.3 mag).  These colors
are consistent with a reddened soft x-ray transient, as suggested
by the estimate of A(V) = 7 deduced from ASCA spectral fitting
(IAUC 6927).  We therefore propose that this object is the true
optical counterpart to XTE J2012+381."
     R. M. Hjellming and M. P. Rupen, National Radio Astronomy
Observatory (NRAO); and A. J. Mioduszewski, Joint Institute for
VLBI in Europe and NRAO, report:  "Very Large Array observations on
June 4.38 UT of the radio candidate for the x-ray transient XTE
J2012+381 (cf. IAUC 6924) showed flux densities of 3.5, 3.0, and
2.6 mJy at 1.4, 4.9, and 8.4 GHz, respectively.  Since the 1.4- and
4.9-GHz data are now significantly greater than on May 31.25 UT
(IAUC 6924), and because of the variability at 15 GHz reported by
Pooley (IAUC 6926), this source is very likely the radio
counterpart of XTE J2012+381.  We can also report an improved
position of R.A. = 20h12m37s.67, Decl. = +38o11'01".2 (equinox
2000.0; uncertainty 0".4)."

                      (C) Copyright 1998 CBAT
1998 June 5                    (6932)            Daniel W. E. Green

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