Central Bureau for Astronomical Telegrams

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IAUC 6933: SGR 1900+14; XTE J2012+381; XTE J1748-288

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IAUC number 

                                                 Circular No. 6933
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)


SGR 1900+14
     B. R. Oppenheimer, J. S. Bloom, S. S. Eikenberry, and K.
Matthews, California Institute of Technology, communicate: "We have
obtained narrowband 2.2-micron images of the proposed infrared
counterpart to SGR 1900+14 (Vrba et al. 1996, Ap.J. 468, 225) on
June 3.486 UT, 4.1 days after the recent bursting activity reported
on IAUC 6929.  Differential photometry of stars 'A' and 'B' (the
double M stars) and star 'C' of Vrba et al. yields m_A-m_B = +0.4
+/- 0.1 and m_A-m_C = +4.5 +/- 0.2 mag, consistent with the
measurements of Vrba et al.  Over the course of 10 min (ten
separate frames), no variability was detected in the double M stars
to a limit of 0.1 mag."


XTE J2012+381
     P. Callanan and J. McCarthy, University College, Cork; and M.
Garcia and J. McClintock, Harvard-Smithsonian Center for
Astrophysics, report:  "Observations of the XTE J2012+381 error
region (IAUC 6920, 6927) were performed using the Cerro Tololo
1.5-m telescope (+ CIRIM detector) on June 1.36, 2.35, 3.35, and
4.36 UT.  The J and K magnitudes of the object near the radio
position (IAUC 6924) were 15.0 +/- 0.1 and 14.3 +/- 0.1,
respectively.  No variability at more than the 10-percent level was
observed in the J and K bands between each night.  Closer
inspection of those images with a FWHM of < 1" reveals an apparent
southeast-northwest elongation of this object, indicating that this
is a composite image of two stars about 1" apart.  This confirms
the detection of the faint red companion to USNO 1275.13846761
found by Hynes and Roche (IAUC 6932).  As the position of the
northwest star is consistent with the improved radio position (IAUC
6932), it may be the true counterpart to the x-ray source.  Further
observations, especially in conditions of good seeing, are
encouraged."


XTE J1748-288
     B. A. Harmon, M. L. McCollough, C. A. Wilson, S. N. Zhang, and
W. S. Paciesas, Marshall Space Flight Center, report for the BATSE
Team:  "This x-ray transient is being detected with BATSE, with the
following average daily fluxes in the bands 20-30 and 50-70 keV:
June 3, 150 +/- 65 and 160 +/- 45 mCrab; June 4, 450 +/- 70 and 280
+/- 45 mCrab.  There was no detection on June 2 (< 75 mCrab).  The
spectrum extends to at least 100 keV and softened significantly
between June 3 (power-law photon number index -2.2 +/- 0.3) and
June 4 (index -2.9 +/- 0.1)."

                      (C) Copyright 1998 CBAT
1998 June 5                    (6933)            Daniel W. E. Green

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