VVV-NOV-002: the second Galactic nova candidate discovered in the Milky Way bulge by the VVV Survey

ATel #4830; R. K. Saito (Pontificia Universidad Catolica de Chile, Universidad de Valparaiso, The Milky Way Millennium Nucleus), D. Minniti (Pontificia Universidad Catolica de Chile, Vatican Observatory, The Milky Way Millennium Nucleus), R. Angeloni (Pontificia Universidad Catolica de Chile) and M. Catelan (Pontificia Universidad Catolica de Chile, The Milky Way Millennium Nucleus)
on 21 Feb 2013; 12:30 UT
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Credential Certification: Roberto Saito (rsaito@astro.puc.cl)

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We report the discovery of the second likely Galactic nova in the VVV Survey data (vvvsurvey.org; Minniti et al. 2010, New Astronomy, 15, 433). Observations taken during 2012 show the presence of a stellar source fading in brightness from March 1st 2012 to October 08 2012 (see table below). The light curve follows the expected behavior of the early stages of a nova outburst, with VVV-NOV-002 fading by Delta_Ks>5.7 mag over 221 days.

The coordinates of VVV-NOV-002 are RA, DEC= 17:32:23.10, -29:48:38.5 (J2000), corresponding to (l,b)= -2.277,1.973 deg. Previous VVV observations taken during 2011 show no detection at the target position, which allow us to infer the nova remnant was fainter than the limiting magnitude of Ks=16.76 mag in the field. The nova outburst occurred between September 24 2011, the last 2011 observation with no detection, and March 1st 2012, when the object is first detected as a saturated source with Ks=8.15 mag.

According to the VVV reddening maps (Gonzalez et al., 2012, A&A, 543, 13) assuming the Cardelli et al. (1989, ApJ, 345, 245 2009) extinction law, the extinction for a 2 arcmin region around the target position is E(J-Ks)=0.54, corresponding to AV=6.67 mag.

There are no previous entries in the literature for the target position.

  
VVV-NOV-002 Table of Observations 
 
Date  (UT)     filter    mag    flag 
2011-05-07.3390  Ks    beyond detection     
2011-07-26.2299  Ks    beyond detection     
2011-08-30.1265  Ks    beyond detection     
2011-09-04.0604  Ks    beyond detection     
2011-09-13.0354  Ks    beyond detection     
2011-09-24.0046  Ks    beyond detection     
2012-03-01.3514  Ks   8.149+/-0.010  -9  
2012-03-24.2745  Ks   8.869+/-0.010  -9  
2012-06-07.1976  Ks  11.586+/-0.010  -1 
2012-06-08.2327  Ks  11.628+/-0.010  -1 
2012-06-21.0333  Ks  11.937+/-0.010  -1 
2012-06-26.0726  Ks  12.122+/-0.010  -1 
2012-07-12.1512  Ks  12.477+/-0.010  +1 
2012-07-14.1707  Ks  12.505+/-0.010  +1 
2012-07-17.1685  Ks  12.558+/-0.010  +1 
2012-07-17.9939  Ks  12.609+/-0.010  +1 
2012-07-27.1015  Ks  12.791+/-0.012  +1 
2012-08-01.0482  Ks  12.931+/-0.012  +1 
2012-08-02.1506  Ks  12.894+/-0.012  +1 
2012-08-12.0111  Ks  13.121+/-0.015  +1 
2012-08-13.1334  Ks  13.078+/-0.015  +1 
2012-08-16.9878  Ks  13.100+/-0.018  +1 
2012-09-10.0695  Ks  13.463+/-0.022  +1 
2012-09-11.9821  Ks  13.557+/-0.022  +1 
2012-09-18.0335  Ks  13.587+/-0.023  +1 
2012-09-19.0093  Ks  13.534+/-0.024  +1 
2012-09-20.0010  Ks  13.651+/-0.024  +1 
2012-10-01.0275  Ks  13.743+/-0.028  +1 
2012-10-02.0127  Ks  13.819+/-0.028  +1 
2012-10-02.0732  Ks  13.771+/-0.027  +1 
2012-10-03.0328  Ks  13.751+/-0.028  +1 
2012-10-08.9968  Ks  13.861+/-0.029  +1 

The VVV data are in the natural VISTA Vegamag system.
Photometric flags are described in Saito et al. 2012 (A&A, 537, A107):
-9 saturated source
-1 stellar object
+1 non-stellar object

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.