Central Bureau for Astronomical Telegrams
IAUC 5814: N IN M31; V1974 Cyg
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Circular No. 5814
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
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MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
NOVA IN M31
R. R. Treffers, B. Leibundgut, and A. V. Filippenko, University
of California at Berkeley; and M. W. Richmond, Princeton University,
report the discovery of a probable nova in M31 at R.A. =
0h40m00s, Decl. = +40 59'.7 (equinox 1950.0), which is about 55"
east and 79" north of the galaxy's nucleus. The object was found
during the Leuschner Observatory Supernova Search, which uses an
automated 0.76-m telescope equipped with the Lawrence Berkeley
Laboratory CCD camera, and it was detected in an image obtained on
June 9 UT at magnitude R = 15.8 +/- 0.3. Confirmation was obtained
on June 11. No object appears at this position to a limit of mag
about 18 in an exposure taken on May 29.
V1974 CYGNI
F. Paresce, Space Telescope Science Institute and European
Space Agency, and the Faint Object Camera Investigation Definition
Team communicate: "The Faint Object Camera on the Hubble Space
Telescope observed V1974 Cyg (Nova Cyg 1992) on May 31 in the
ultraviolet (FOC filter F278M, whose bandpass peaks at 0.28 nm and
encompasses several emission lines of ionized neon, magnesium, and
oxygen between 0.25 and 0.3 nm). The image reveals a circular ring
of emission of radius 0".130 +/- 0".020 centered on the star. The
azimuthal surface brightness profile peaks in the northwest sector
of the ring at a level comparable to that of the central star and a
factor of two above that of the southeast sector at these wavelengths.
A bridge of emission links the star to the ring at position
angle 30 deg. Residual emission in the region between the
ring and the star that is not due to spillover from the wings of
the point spread function indicates that the ring is most likely
due to a thin, inhomogeneous, limb-brightened shell of emitting
material. A preliminary estimate of the brightness ratio of the
limb and the half-radius point yields an upper limit to the shell
thickness of 10 percent of the radius. Comparison with observations
taken soon after outburst (IAUC 5463) show that the shell has
been expanding at a constant angular rate of 0".00028/day. Assuming
an average velocity of expansion of 1500 km/s, the observed
ring location and epoch imply a source distance of 3.2 kpc."
1993 June 11 (5814) Daniel W. E. Green
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