We report the discovery of a likely Galactic nova in the VVV Survey data (vvvsurvey.org; Minniti et al. 2010, New Astronomy, 15, 433). Observations taken during 2010-2013 show the presence of a stellar source fading in brightness from April 21 2010 to September 25 2013 (see table below). The light-curve of VVV-NOV-004 follows the expected behavior of a nova during the late stages of an outburst, fading by Delta_Ks>2.2 mag over 1253 days.

The coordinates of VVV-NOV-004 are (RA,DEC)=17:43:33.52, -30:30:29.10 or (l,b) =1.57391,-0.44046, with an accuracy of ~0.35 arc seconds. Previous near-IR observations from UKIDSS (Lucas et al. 2008, MNRAS, 391, 136) and 2MASS (Skrutskie et al. 2006, AJ, 131, 1163) show no detection at the object position. The possible nova outburst occurred before April 21 2010, when the object is first detected as a stellar source with Ks=13.17 mag and (J-Ks)=4.32 mag. In the latest data-point currently available the object has Ks=15.40 mag.

According to the VVV reddening maps (Gonzalez et al., 2012, A&A, 543, 13) assuming the Nishiyama et al. (2009, ApJ, 696, 1407) extinction law, the extinction for a 2 arcmin region around the target position is E(J-Ks)=2.77, corresponding to AV=12.4 mag.

There are no previous entries in the literature for the target position. Confirming the nature of the object, VVV-NOV-004 would become the innermost known nova in the Galactic bulge. We recommend further observations in order to discard the hypotheses of a rare long period variable or an OH/IR star with P>1250 days.

The VVV data are in the natural VISTA Vegamag system. Photometric flags are described in Saito et al. 2012 (A&A, 537, A107)

Acknowledgments: We gratefully acknowledge use of data from the ESO Public Survey programme ID 179.B-2002 taken with the VISTA telescope, and data products from the Cambridge Astronomical Survey Unit.