Central Bureau for Astronomical Telegrams
IAUC 6097: N Cas 1993; Poss. GRAVITATIONAL MICROLENSING EVENT; 1994l
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Circular No. 6097
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)
NOVA CASSIOPEIAE 1993
S. J. Boyle, University of London Observatory, writes: "Images
of N Cas 1993 were obtained by M. Pontefract and K. Siebert with
the 0.6-m Radcliffe refractor (+ CCD) at the University of London
Observatory on Oct. 4. A slightly asymmetric region of emission
was detected, with a radius of about 9". This region is larger
than predicted by any plausible rate of expansion of the shell
produced by the nova's outburst on 1993 Dec. 4. We attribute the
emission to the excitement of material previously ejected from the
progenitor star and estimate that the episode of mass-loss occurred
at some epoch between 1920 and 1960. Spectra in the range 540-700
nm obtained simultaneously by J. Bly and P. Newman with the 0.6-m
Allen reflector show emission lines due to H-alpha, O I (630.0 nm),
and N II (575.5 nm). S. Boyle measured the HWZI of the last-noted
line to be 970 km/s."
POSSIBLE GRAVITATIONAL MICROLENSING EVENT
E. Giraud, European Southern Observatory, writes: "I have
obtained two exposures, with the New Technology Telescope at La
Silla on the night of Oct. 18-19, of the microlens candidate in the
Large Magellanic Cloud reported by the MACHO collaboration (IAUC
6095). Images were obtained with a Bessel R filter (central
wavelength 645.0 nm; FWHM 155.0 nm). I also obtained a spectrum
(range 600-800 nm) on the same night. The microlens candidate has
a faint companion to the east; this explains why the reference
image provided in the anonymous FTP account (ibid.) appears to be
elongated. The difference in magnitude of the lens candidate
between the reference frame and the present observation is 0.89 +/-
0.2 mag; the accuracy in relative photometry of the present
measurement is 0.06 mag, while that of the reference frame is of
the order of 0.2 mag. (A better determination of the zero point,
coadding reference frames, can considerably reduce the error.) The
spectrum shows a weak detection of H-alpha in absorption."
PERIODIC COMET BORRELLY (1994l)
Total visual magnitude estimates by C. S. Morris (southern
California, 0.26-m reflector): Oct. 2.47 UT, 9.0; 3.47, 8.9; 7.47,
8.8; 8.48, 8.8; 9.48, 8.8; 12.44, 9.0.
1994 October 20 (6097) Daniel W. E. Green
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