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IAUC 6860: AX J0051-73.3 = RX J0050.7-7316; GRB 980329; 1998S

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                                                 Circular No. 6860
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)
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Phone 617-495-7244/7440/7444 (for emergency use only)


AX J0051-73.3 = RX J0050.7-7316
     K. Cook, Lawrence Livermore National Laboratory, reports that
the MACHO collaboration (cf. IAUC 6312) has detected an eclipsing
variable star with peculiar properties within 2".0 of the position
for AX J0051-73.3 reported on IAUC 6854.  Located at R.A. =
0h50m44s.7, Decl. = -73o16'05" (equinox J2000.0), this is the
nearest source in our database to the position of the x-ray source
and is well within the reported 90-percent-confidence region.  The
lightcurve has mean V = 14.7 and V-R = +0.2, with a pronounced,
long-term baseline brightness variation of 0.1 mag from 1993 June
18.7 UT to the present.  A persistent contact-binary-like
lightcurve with period 0.708 days and peak-to-peak amplitude of
0.10 mag is seen superposed on the much longer timescale variation.
The MACHO Project data are acquired at the 1.5-m telescope at Mount
Stromlo Observatory.


GRB 980329
     J. M. Quashnock, D. E. Vanden Berk, D. M. Cole, A. R. Cooray,
D. Q. Lamb, F. J. Castander, K. Gloria, and D. Long, University of
Chicago, on behalf of the Astrophysical Research Consortium,
report:  "Between Apr. 1.167 and 1.277 UT, we made near-infrared
observations of a region of the sky that includes the entire
BeppoSAX NFI error box for GRB 980329 (IAUC 6853, 6854), using the
GRIM II instrument mounted on the ARC 3.5-m telescope at Apache
Point Observatory.  During Apr. 1.167-1.177, at R.A. = 7h02m38s.7,
Decl. = +38o50'27" (equinox 2000.0) -- consistent with the
position of the object of mag R = 20.6 noted on IAUC 6856 -- we
find an object of mag J = 17.7 +/- 0.1; during Apr. 1.267-1.277
(about 2.5 hr later), we find no measurable change (less than about
0.1 mag) in the J magnitude of the object.  This object is about
6".4 south and 3".0 west of the bright (R = 15.8) star reported on
IAUC 6856, for which we measure J = 13.9 +/- 0.1."


SUPERNOVA 1998S IN NGC 3877
     P. Garnavich, S. Jha, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, report: "Spectra of SN 1998S by P. Berlind
and M. Calkins with the 1.5-m Tillinghast telescope show that a
deep, broad absorption feature (with a minimum observed at 628.6
nm) has developed in the already-unusual type-II spectrum.
Assuming the same expansion velocity as He I 587.5-nm (4600 km/s),
the feature has a rest wavelength of 636 nm.  This likely
corresponds to the Si II blend (634.7, 637.1 nm) often seen in
type-I supernovae."

                      (C) Copyright 1998 CBAT
1998 April 3                   (6860)            Daniel W. E. Green

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