Central Bureau for Astronomical Telegrams
IAUC 6095: Poss. GRAVITATIONAL MICROLENSING EVENT; OJ 287 AND 3C 66A
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Circular No. 6095
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 GRAVITATIONAL MICROLENSING EVENT
The MACHO collaboration (cf. IAUC 6068) reports the discovery
of a possible gravitational microlensing event in progress toward
the Large Magellanic Cloud: "The star in question is located at R.A.
= 5h17m14s.6, Decl. = -70o46'59" (equinox 2000.0); it was constant
at R = 19.8, V = 20.1 during 1993 and mid-1994, and it has brightened
by 0.75 mag during the two weeks prior to Oct. 13, while its color
appears unchanged. Magnitude estimates from the CCD on the 1.27-m
telescope at Mt. Stromlo: 1994 Sept. 25.72 UT, V = 19.87; Oct. 5.65,
19.63; 10.70, 19.50; 13.65, 19.36 (errors typically 0.10 mag). If
this event is due to gravitational microlensing, a preliminary fit
predicts that the star should reach a peak of V < 19.2 between Oct.
15 and 30, and then decline symmetrically. As the light curve is
currently incomplete and the star is faint, it should be emphasized
that the microlensing interpretation is still tentative. Because
this star is faint, the data obtained with our routine observations
at the Mt. Stromlo 1.27-m telescope may not be sufficient for an
accurate determination of the light curve shape. Thus, accurate
photometry and low-resolution spectroscopy of this star at regular
intervals during the next 14 days will be very valuable to test the
microlensing interpretation. Light curves and a finding chart are
available by anonymous FTP (address lensing.physics.ucsb.edu in the
directory macho/alert/lmc1; this directory will be periodically
updated with new light curves and microlensing fits as the data
come in). Potential observers are requested to contact D. Bennett
(telephone USA 510-423-0656; e-mail bennett@igpp.llnl.gov) to
coordinate observations."
OJ 287 AND 3C 66A
M. Fiorucci and G. Tosti, Dipartimento di Fisica, Universita
di Perugia, write: "During our photometric monitoring program of
blazars, we have found that OJ 287 and 3C 66A are in a high-luminosity
stage, as indicated by the following photometry obtained with the
0.4-m reflector (+ CCD) of the Perugia Automatic Observatory using
Cousins BVRI bands: OJ 287: May 15 UT, V = 15.50; Oct. 11.11, B =
14.86, V = 14.47, R = 14.04, I = 13.40; Oct. 12.16, 14.81, 14.35,
13.96, 13.34. 3C 66A: Oct. 11.07, B = 14.55, V = 14.23; Oct.
12.04, 14.52, 14.15."
1994 October 14 (6095) Daniel W. E. Green
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