Swift X-ray and UV observations of Nova Oph 2012

ATel #4055; Thomas Nelson (Minnesota), Koji Mukai (UMBC and NASA/GSFC), Jennifer Sokoloski (Columbia), Laura Chomiuk (NRAO and CfA), Michael Rupen (NRAO) and Amy Mioduszewski (NRAO)
on 19 Apr 2012; 23:24 UT
Credential Certification: Thomas Nelson (tnelson@physics.umn.edu)

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Nova Oph 2012 (PNV J17260708-2551454) was discovered on 2012 March 25.8 (H. Nishimura, CBET 3072). The current AAVSO optical light curve reveals a complex outburst evolution, characterized by dramatic fading and re-brightening that has similarities to the early evolution of V1280 Sco (Hounsell et al. 2010). We observed Nova Oph 2012 with the Swift satellite between 2012 April 15.8 and 2012 April 17.0, 22 days after the initial discovery. The total exposure time was 6170 s. No X-ray source is detected at the position of the nova in the XRT image.

Using the Bayesian upper limit method outlined in Kraft, Burrows & Nousek (1991), we derive a 90% confidence upper limit to the 0.3-10 keV count rate of 7.4 x 10^-4 c/s. Assuming 5 keV thermal bremsstrahlung attenuated by an absorbing column of 10²² cm^-2 (see discussion in Mukai, Orio & Della Valle, 2008), this count rate limit corresponds to a 0.3-10 keV flux limit of 4.4 x 10^-14 erg/s/cm^-2.

The UVOT instrument also obtained images of Nova Oph 2012 in the U (t_exp = 960 s) and UVW2 (t_exp = 5090 s) bands. The nova is clearly detected in both images, with U = 12.23 +/- 0.03 mag, and UVW2 = 15.46 +/- 0.02 mag.

These observations were obtained as part of the E-Nova project (formerly the EVLA Nova Project, see link below), an effort to obtain high quality radio light curves and complimentary multiwavelength observations of novae visible to the Jansky Very Large Array. We have approved programs to obtain additional X-ray and radio observations of this nova as the outburst evolves.

Hounsell, R., Bode, M. F., Hick, P. P. et al., 2010 ApJ 724, 480
Kraft, R. P., Burrows, D. N. & Nousek, John, A. 1991 ApJ 372, 344
Mukai, K., Orio, M. & Della Vale, M. 2008 ApJ 677, 1248

E-Nova Project