2009CBET.1912....1M

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.