CBET 1182 : 20071228 : SUPERNOVA 2007sv IN UGC 5979
SUPERNOVA 2007sv IN UGC 5979
G. Duszanowicz, Akersberga, Sweden, reports his discovery of an
apparent supernova (mag 17.4) on unfiltered CCD exposures (limiting mag
18.5) taken on Dec. 20.912 UT with a 0.32-m f/3.1 reflector (+
Starlight Xpress MX716 CCD camera). The new object is located at R.A. =
10h52m40s.05 +/- 0s.04, Decl. = +67o59'14".2 +/- 0".7 (equinox 2000.0;
mean of measurements from Dec. 20, 26, and 28 images), which is
6".9 west and 6".7 south of the center of UGC 5979. Nothing appeared at
this position on a CCD image by Duszanowicz on Sept. 13.093 (limiting
mag 18.8 ). A confirming unfiltered CCD image (limiting mag 18.0) was
obtained by T. Boles on Dec. 25.971, showing 2007sv at mag 17.4 and
position end figures 40s.08, 14".5. Duszanowicz additionally obtained
300-s unfiltered CCD images on Dec. 26.829 (very poor sky conditions)
and 28.135 (limiting mag 19.4) showing the new object at mag 17.6 (only
a few tenths of a magnitude above his limit) and 17.1, respectively.
Following posting on the CBAT's unconfirmed-objects webpage, P. Corelli
(Pagnacco, Italy) writes that his thirty co-added 30-s images (limiting
mag 18.8 ) taken on Dec. 27.855 with a 0.45-m f/4.5 telescope show 2007sv
at mag 17.4; comparison with a red Digitized Sky Survey image shows
nothing at the position of the new object (limiting mag presumed to be
20-21).
CBET 1184 : 20071230 : 2007sv
2007sv
A. Harutyunyan, H. Navasardyan, S. Benetti, and M. Turatto, Istituto
Nazionale di Astrofisica, Padua; A. Pastorello, Queen's University; and S.
Taubenberger, Max-Planck Institute for Astrophysics, report that inspection
of a low-signal-to-noise CCD spectrogram obtained on Dec. 29.96 UT with the
Asiago 1.82-m telescope at Mt. Ekar (+ AFOSC) reveals that the spectrum of
2007sv (cf. CBET 1182) has a blue continuum with unresolved (FWHM < 1000
km/s) H Balmer lines in emission. The spectral characteristics of 2007sv,
together with its faint absolute magnitude (around -14, assuming association
with UGC 5979), suggest that this object might not be a real supernova but
a super-outburst of a luminous blue variable similar to 1997bs [Van Dyk et
al. 2000 (PASP 112, 1532) suggested that 1997bs was less likely to be a
type-IIn supernova, as reported on IAUC 6627, than a superoutburst of a very
massive luminous blue variable star].
