Radio, X-ray and UV observations of Nova Sgr 2012

ATel #4088; 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 3 May 2012; 19:17 UT
Credential Certification: Thomas Nelson (tnelson@physics.umn.edu)

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Nova Sgr 2012 (PNV J17452791-2305213) was discovered on 2012 Apr 21 (CBET 3089). The optical evolution during the first 5 days was captured in great detail by the STEREO mission, revealing a very fast decay from maximum brightness (see http://stereo.gsfc.nasa.gov ). Early spectroscopy indicated high velocity ejecta in this nova, with an H alpha line FWHM of 5600 km/s (CBET 3089). Sokolovsky et al. observed Nova Sgr with Swift one day after discovery, and reported a non-detection in X-rays (ATel #4061).

We observed Nova Sgr 2012 with the Jansky Very Large Array at Ka band (32 GHz) on 2012 April 23.5, 3 days after initial discovery. Our observation resulted in a non-detection of 32 +/- 25 microJy at the position of the nova.

We also observed the nova with Swift/XRT for 5955 s between 2012 April 25.7 and 2012 April 26.1, approximately 6 days after the initial discovery. No X-ray source was detected at the position of the nova, with a 90% confidence upper limit to the 0.3-10 keV count rate of 1.3e-3 c/s. Assuming 5 keV thermal bremsstrahlung emission attenuated by an absorbing column density of 1e22 cm^-2, this count rate limit corresponds to a 0.3-10 keV flux limit of 7.8e-14 erg/s/cm^-2.

The UVOT instrument also obtained images of Nova Sgr 2012 in the UVM2 band on 2012 Apr 25.7, with a total exposure time of 5975 s. The nova is clearly detected, with an average UVM2 brightness of 13.71 +/- 0.09 mag. Over the course of our observation, the UVM2 magnitude faded from 13.5 to 13.8.

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. Further radio and X-ray observations of this nova are planned.

E-Nova Project