[IAUC] CBET 1912: 20090818 : NOVA OPHIUCHI 2009

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                                                  Electronic Telegram No. 1912
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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NOVA OPHIUCHI 2009
     U. Munari, T. Saguner, P. Ochner, and A. Siviero, Istituto Nazionale di
Astrofisica, Padova Astronomical Observatory; and A. Maitan, P. Valisa, S.
Dallaporta, and S. Moretti "Asiago Novae and Symbiotic Stars" (ANS)
collaboration, report that CCD photometry of N Oph 2009 (cf. CBETs 1910, 1911)
was obtained on Aug. 17.47 and 18.49 UT, providing V = 12.63 and 13.05, B-V =
+1.81 and +1.66, V-R_c = +1.79 and +1.67, and V-I_c = +2.82 and +2.58,
respectively.  A medium-resolution CCD spectrogram (0.06 nm/pixel; range
540-670 nm) was obtained on Aug. 17.83 UT with the 1.22-m telescope of the
Asiago Astrophysical Observatory.  The spectrum is dominated by a very strong
H-alpha in emission on top of a featureless continuum showing interstellar
Na I and diffuse intertellar bands (in particular at 577.9, 628.4 and 661.4
nm) in strong absorption.  H-alpha has an equivalent width of 53 nm and
an integrated flux of 5.3 x 10**(-11) erg cm**(-2) s**(-1).  The profile of
the emission line is highly structured, in the form of a broad trapezium with
a sharper Gaussian on top.  The trapezium has a velocity width of 11500
km/s at the base and 6900 km/s at the top; the sharp Gaussian component has a
FWHM of 1400 km/s.  An absolutely fluxed, low-resolution CCD spectrogram
(0.21 nm/pixel; range 400-870 nm) was obtained on Aug. 17.87 with the 0.6-m
telescope of the Schiaparelli Observatory in Varese; this spectrum confirms
the quite-red spectral energy distribution and the very wide profiles of the
emission lines.  Those clearly detected include H-alpha, H-beta, O I 844.6-nm,
and possibly He I 706.5-nm; their fluxes, in units of 10**(-11) erg cm**(-2)
s**(-1), are 5.0, 0.13, 2.3, and 0.36, respectively.  The colors, the rapid
decline, and the velocity of the ejecta suggest that N Oph 2009 is a highly
reddened outburst occourring on a massive white dwarf, not dissimilar from
the U-Sco type of recurrent novae.  A search in plate archives for missed
previous outbursts could pay dividends.


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                         (C) Copyright 2009 CBAT
2009 August 18                   (CBET 1912)              Daniel W. E. Green