Central Bureau for Astronomical Telegrams
IAUC 6164: Poss. MICROLENSING IN THE GALACTIC BULGE; AL Com
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 6165
.dvi or
.ps format.
Circular No. 6164
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444 TWX 710-320-6842 ASTROGRAM CAM
MARSDEN@CFA.HARVARD.EDU or GREEN@CFA.HARVARD.EDU (science)
POSSIBLE MICROLENSING IN THE GALACTIC BULGE
A. Udalski and M. Szymanski, Warsaw University Observatory, on
behalf of the OGLE microlensing search team, communicate: "The OGLE
'Early Warning System' (cf. IAUC 5997; Udalski et al. 1994, Acta
Astron. 44, 227) has detected an object in the galactic bulge that
fulfills the criteria of a 'prime microlensing candidate'.
Observations collected since Apr. 11 (the beginning of the OGLE 1995
season) with the 1-m Swope telescope at the Las Campanas Observatory
have shown that the star (R.A. = 18h06m48s.68, Decl. = -26o37'24".0,
equinox 2000.0) had brightened about 0.6 mag, while in the 1993 and
1994 observing seasons the star was constant at I = 19.08 and V-I =
+2.3. On Apr. 18.25 UT, its brightness was I about 18.65. The
star seems to be on the declining branch of the microlensing lightcurve,
3-5 days after maximum. However, due to the short period of
observations in the 1995 season, we are not yet able to determine
the microlensing lightcurve parameters, and we cannot rule out the
possibility that the brightening is related to some other kind of
variability. We strongly encourage follow-up observations in many
wavelength pass-bands to confirm the microlensing hypothesis. A
finding chart, lightcurve, and regularly updated photometry can be
found in the OGLE archive (anonymous ftp sirius.astrouw.edu.pl,
directory /ogle/ews/1995/mm1-a)."
AL COMAE BERENICES
D. Nogami and T. Kato, Department of Astronomy, Kyoto
University, write: "V-band CCD photometry obtained with a 0.60-m
reflector at Ouda Station, Kyoto University, indicates that the
humplike feature reported independently by Patterson and by DeYoung
(IAUC 6157) showed a continous decay until Apr. 12. The data
between Apr. 17.440 and 17.691 UT clearly demonstrate a periodic
modulation with a period of 0.0576 +/- 0.0002 day and an amplitude
of 0.18 mag. This period is slightly longer than those reported
earlier and one (0.05666 +/- 0.00002 day) determined by us from
Apr. 7-12 observations. This fact indicates that the new features
are genuine superhumps, and earlier detection may reflect a
variation related to the orbital motion of the underlying binary.
The present observation thus first firmly identifies the SU UMa-
type nature of AL Com. However, the baseline is not so long.
Follow-up observations are expected."
1995 April 19 (6164) Daniel W. E. Green
Read IAUC 6165
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
