GRB 970912                                                         #002
 
D. A. Smith, A. M. Levine, E. H. Morgan, and R. A. Remillard (MIT), on
behalf of the RXTE/ASM team at MIT and NASA/GSFC, and R. Rutledge (MPE)
report:

The RXTE All Sky Monitor has detected the gamma-ray burst of
Sep. 12.25652 UT that was logged as BATSE trigger no. 6377.  The burst
was detected by ASM camera 3 as a bright X-ray flash that lasted ~2.8
s and yielded a peak count rate of ~270 cts/s. The inferred peak flux,
including corrections for background and location in the field of
view, is ~10 Crab (2-12 keV).  The instrument software issued a
command to turn off the detector high voltage ~10 seconds after the
burst, presumably because of a high background count rate induced by
the burst itself.  This eliminated the opportunity for observations of
the burst location by the same camera (i.e., no. 3) from a different
position angle ~25 seconds after the burst.  Our results are therefore
limited to a single detection, yielding an error box (90% confidence)
with dimensions 2.2 degrees by 3.5 arcminutes.  The corners of this
box are at R.A. = 18h25m39.0s, Decl. = -14o51'48"; 18h25m42.6s,
-14o48'50"; 18h34m24.9s, -15o28'10"; 18h34m4.5s -15o23'31" (equinox
2000).  If the long dimension of this error box is extended, it would
lie only ~10 arcmin from GX 17+2, which was in the field during the
burst.  We have checked for possible interference from that source and
do not believe that it is a serious problem.


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This event is no longer classified as a GRB -- it is an SGR.


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                                                                     #003
Don Smith on behalf of the RXTE-ASM team reports for SGR on 970912:

We have extended the ASM position determination of the SGR detected on
1997 Sept 12 by the ASM, BATSE, and Ulysses.  The box intersects with
the IPN arcs at the southern tip of the diamond.  We recommend
observers consider a circle with a radius of 5 arcminutes, centered on
the position R.A. = 18h14m25s, DEC = -14o1.7' (J2000)


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                                                                     #004
The following report from A. Hendon et al. on the recent "possible new SGR"
(ref IAUC 6743) has also been submitted to the IAUC:


A. Henden, Universities Space Research Corporation (USRA) and U. S. Naval
Observatory, Flagstaff Station (USNOFS)  aah@nofs.navy.mil
C. Luginbuhl, USNOFS     cbl@nofs.navy.mil
F. Vrba, USNOFS          fjv@nofs.navy.mil
B. Canzian, USRA/USNOFS  bjc@nofs.navy.mil
J. Munn USNOFS           jam@nofs.navy.mil
D. Hartmann, Clemson University  hartmann@grb.phys.clemson.edu

We report a strong near-IR source about 2 arcmin from the the center
of the IPN error box for GRB970912 (IAUC 6743), located at RA = 18:14:50.31,
DEC = -13:41:05.6 (J2000, +-0.5arcsec).  JHK images saturate in our shortest
available exposure (0.16 sec), but we estimate approximate magnitudes
of J = 7.4, H = 6.0, K = 5.1.  This object is coincident with IRAS 18119-1337
within the errors of the positions.  CCD images with limiting magnitudes
around 20-21 show the object barely visible at V, but easily visible
at R and bright at I.  The object is barely on the POSS-I red plate.
While the GRB error box center has been recently revised based on RXTE ASM
data (D. Smith, priv. comm.) to a point some 20 arcmin south of the IPN
center, we note the similarity of this source to the potential IR counterparts
of SGR 1900+14.


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Please note that in the above announcement, the association with
IRAS 18119-1337 should actually be with IRAS 18119-1342.  This error was
corrected in the IAUC# 6744.


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George Djorgovski reports:                                             #005

IRAS 18119-1342 and the possible new SGR

  We obtained a spectrum of the IR source IRAS 18119-1342, mentioned in 
  IAUC 6744 by Henden et al. as a possible counterpart of the SGR 18.....
  The spectrum is of the M-type, exremely red (as expected), and shows no
  apparent emission lines, including H-alpha.  Our best guess is that it is
  an obscured M supergiant, unrelated to the SGR.  There is no need for anyone
  else to waste any more telescope time on this object, I think.  Forgot to
  mention: the data were obtained at the Palomar 200-inch on 22 Sep 97 UT,
  and the result can be cited as "Djorgovski et al., priv. comm."

  Best regards, George Djorgovski (george@oracle.caltech.edu)