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IAUC 6720: MICROLENSING EVENT; AG Dra; V4368 Sgr

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                                                 Circular No. 6720
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/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


MICROLENSING EVENT
     A. C. Becker, D. P. Bennett, N. Butler, B. A. Peterson, S. H.
Rhie, S. E. Thomson, S. E. Turner, and the MACHO collaboration (cf.
IAUC 6312) write:  "We predict a high-magnification for event 97-
BLG-56, a gravitational microlensing event in progress toward the
Galactic Bulge.  The source star, located at R.A. = 17h55m28s.7,
Decl. = -29o33'42" (equinox 2000.0), appears to be a giant with
unamplified magnitudes of V = 16.1, R = 14.8.  The current
microlensing fit predicts a peak amplification of > 5 on 1997 Aug.
24.  Due to the star type and the high magnification of this event,
it is expected that finite source effects such as changes in color
and spectral-line equivalent widths will be observable.
Spectroscopy and infrared photometry at or near peak will be
invaluable in studying this unusual event.  A finding chart and
additional information are available by anonymous ftp at
darkstar.astro.washington.edu:/macho/Alert/97-BLG-56 or on the WWW
at http://darkstar.astro.washington.edu/.  Potential observers are
asked to email gman@mso.anu.edu.au or telephone E. Turner at
(Australia) 6-249-0209 or 6-288-4727 to coordinate observations."


AG DRACONIS
     M. Mikolajewski, Centre for Astronomy, N. Copernicus
University, Torun, reports an increase in brightness since April in
all optical bands: Apr. 26.90 UT, U = 11.26, B = 11.31, V = 9.91, R
= 8.44, I = 7.78; Aug. 16.95, 9.27, 9.99, 9.08, 7.78, 7.27; 17.85,
9.21, 9.95, 9.09, 7.77, 7.27; 18.86, 9.17, 9.94, 9.05, 7.73, 7.21.
     E. Waagen, AAVSO, reports that, after being at minimum for
about 7.5 yr, AG Dra brightened in May-July 1994 (to m_v = 8.3),
then again in June-July 1995 (mag 8.9) and June-July 1996 (mag 9.4).
The current brightening began in late May 1997.  Recent visual
magnitude estimates:  Aug. 1.93 UT, 9.1 (G. Poyner, Birmingham,
England); 5.46, 9.2 (G. Hanson, Cave Creek, AZ); 15.94, 8.8
(Poyner); 17.96, 9.2 (B. Granslo, Fjellhamar, Norway).


V4368 SAGITTARII
     G. J. Garradd, Loomberah, N.S.W., reports the following
precise CCD position for this object (cf. IAUC 5961, 5976),
obtained on Aug. 19.395 UT (mag R = 10.5): R.A. = 18h54m40s.34,
Decl. = -19o41'59".7 (equinox 2000.0).
     Recent AAVSO visual magnitude estimates:  June 28.2 UT, 10.5
(J. Bortle, Stormville, NY); July 13.8, 10.2 (L. A. G. Monard,
Pretoria, South Africa); Aug. 2.8, 10.2 (Monard); 6.8, 10.3
(Monard); 10.8, 10.2 (Monard).

                      (C) Copyright 1997 CBAT
1997 August 20                 (6720)            Daniel W. E. Green

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