Central Bureau for Astronomical Telegrams
IAUC 7188: MICROLENSING EVENT TOWARDS THE LMC; V382 Vel
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Circular No. 7188
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 ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)
MICROLENSING EVENT TOWARDS THE LMC
A. Becker, University of Washington, reports on behalf of the
MACHO, OGLE, and MPS collaborations on the progress of a high-
magnification microlensing event, designated MACHO 99-LMC-2,
regarding a star at R.A. = 5h16m53s.2, Decl. = -69o16'30".2
(equinox 2000.0), which was constant in brightness (I = 19.9, R =
20.6, V = 21.0) since Jan. 1997 and was at a magnification of 16.3
(a brightening of 3 mag) as of 1999 June 4.4 UT. The best fit to
microlensing indicates the object will reach a (currently
unconstrained) maximum magnification near June 8.23 +/- 0.6 day (a
fit 2-sigma away provides a maximum magnification of 44.5 on June
7.94 +/- 0.1 day). The brightening of the source allows for high-
S/N photometry to constrain exotic microlensing phenomena (binary-
source effects; 'parallax' effect), which lead to constraints on
the lens location. High-S/N spectroscopy of the lensed source
(presumably on the LMC main sequence) may become feasible, as it is
expected to reach at least I = 15.8. This configuration also
allows for enhanced planet-detection efficiency, if the lens
harbors a planetary system. Observers should contact
macho@astro.washington.edu or A. Becker at telephone 206-543-9205
to coordinate observations. A finding chart and data on this event
may be found at
ftp://darkstar.astro.washington.edu/macho/Alert/99-LMC-2/.
V382 VELORUM
B. Hidayat, M. Ikbal Arifyanto, J. Aria Utama, and S. Athiya,
Bosscha Observatory, Lembang, write: "Spectroscopic observations of
N Vel 1999 were obtained at the Bosscha Schmidt telescope (+
objective prism; dispersion 31.5 nm/mm at H-gamma) on June 1.50 and
2.50 UT, with unfiltered IIa-O plates exposed for 12 and 6 min,
respectively. Although the 12-min exposure yielded an overexposed
spectrum, emission lines of H, He, and [O III] are clearly
distinguishable. Based on the three spectra collected on June 2,
the following lines are seen (positions and widths of the lines are
based on a standard spectrum of a B9 star, secured with the same
telescope): [O III] 500.7-nm (half the strength of H-beta), 495.9-
nm (half the strength of H-beta), 436.3-nm (certainly observable);
[Fe II] 492.4-nm (rather faint but traceable), 423.3-nm (faint); S
II(?) 406.8-nm (rather broad, confuse, barely visible); [Ne III]
386.9-nm (half the strength of H-beta). All of the H lines down to
H_7 appear on our plates; their estimated width is about 20.0 nm,
decreasing rather slowly toward H_7. Shallow depression on the
blue side of H-beta is noticable. He II 468.6-nm is rather wide."
(C) Copyright 1999 CBAT
1999 June 4 (7188) Daniel W. E. Green
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