2007CBET.1010....1M

U. Munari, M. Orio, and M. Valentini, Istituto Nazionale di Astrofisica, Padova Astronomical Observatory; K. L. Page and J. P. Osborne, Department of Physics and Astronomy, University of Leicester; and S. Dallaporta, P. Valisa, G. DallaVia, and A. Stanzione, ANS (Asiago Novae and Symbiotic stars) collaboration write that V5558 Sgr = N Sgr 2007 spent the first seventy days following its discovery (on Apr. 14.78 UT; cf. IAUC 8832) on an unusual, very protracted pre-maximum halt, during which it rose in brightness by just 1 magnitude, and they report on their CCD photometry of the nova, acquired almost daily with ANS telescopes since the object's discovery. On June 27 (when the nova was at V = 7.93, B-V = +0.90, V-Ic = +1.43), it suddenly entered a new phase characterized by a much steeper rise in brightness that took the nova to a maximum attained around July 10.0 at V = 6.53, B-V = +0.96, and V-Ic = +1.22. Starting at July 12.0 UT (when it was at V = 6.59, B-V = +1.09, and V-Ic = +1.32), V5558 Sgr entered a rapid decline that brought the nova down to V = 8.37, B-V = +1.12, V-Ic = +1.94 by July 19.96. The decline rate seems to have considerably slowed around July 19-20, in correspondence with the nova regaining the brightness of the extended pre-maximum halt. Only continued monitoring will tell if the occurring of the last month have been an isolated flare on top of an unusual, very slow, and flat photometric evolution or instead the start of a normal decline toward quiescence.