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IAUC 7399: XTE J1550-564; 2000bi; 2000B, 2000I, 2000K, 2000Q

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IAUC number

                                                  Circular No. 7399
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  ISSN 0081-0304
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XTE J1550-564
     D. A. Smith, A. M. Levine, R. Remillard, and D. Fox,
Massachusetts Institute of Technology; and R. Schaefer, Goddard
Space Flight Center, NASA, on behalf of the RXTE/ASM Team, report:
"Observations over Apr. 6-10 with the RXTE All-Sky Monitor show a
clear detection of a source with maximum likelihood position 1' +/-
3' from the position of XTE J1550-564 (IAUC 7009, 7197, etc.).  It
is therefore highly likely that we have detected renewed activity
of XTE J1550-564.  A 2-12-keV light curve from this location shows
an approximately linear flux increase at a rate of about 15 +/- 2
mCrab/day.  Extrapolation of this rate indicates zero flux on Apr.
2.  The energy spectrum is slightly harder than that of the Crab,
and there is as yet no evidence for spectral evolution."
     N. Masetti, Istituto Tecnologie e Studio Radiazioni
Extraterrestri, CNR, Bologna; and R. Soria, Mullard Space Science
Laboratory, University College, London, communicate:  "We observed
the optical counterpart of the soft-x-ray transient XTE J1550-564
on Apr. 10.58 UT, using the CCD imager on the 1.02-m telescope at
Siding Spring Observatory.  From a preliminary analysis of the
data, we find B = 19.73 +/- 0.05, V = 18.14 +/- 0.03, R = 17.16 +/-
0.05.  This shows that XTE J1550-564 is again in an outburst phase.
Further multiwavelength observations of the source are encouraged."
Soria and Masetti add that further CCD images of the optical
counterpart, centered on Apr. 10.79 UT, show that the source is
brightening at a rate of 0.30 +/- 0.05 mag/day in the B band, 0.25
+/- 0.05 mag/day in the V band, and 0.20 +/- 0.03 mag/day in the R

     Further to his report on IAUC 7398, M. M. M. Santangelo adds
that SN 2000bi is slightly brighter than the faint star that lies a
few arcsec north of the galaxy nucleus.

SUPERNOVAE 2000B, 2000I, 2000K, 2000Q
     Unfiltered CCD magnitude estimates by K. Sarneczky, K.
Sziladi, and L. Kiss, Piszkesteto station, Konkoly Observatory:
SN 2000B in NGC 2320, Mar. 13.82 UT, 18.0 +/- 0.3; SN 2000I in
NGC 2958, Mar. 15.91, 18.2 +/- 0.3; SN 2000K in MCG +9-19-191,
Mar. 13.89, 18.7 +/- 0.3; SN 2000Q, Mar. 16.12, 17.3 +/- 0.2.

                      (C) Copyright 2000 CBAT
2000 April 10                  (7399)            Daniel W. E. Green

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