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ATEL # 1327; J.-U. Ness, S. Starrfield (Arizona State), G. Schwarz (West Chester), J.P. Osborne and K.L. Page (University of Leicester)
on 14 Dec 2007; 16:52 UT
Password Certification: Kim Page (firstname.lastname@example.org)
Subjects: Ultra-Violet, X-ray, Cataclysmic Variables, Nova, Transients
Two Swift XRT observations of V574 Pup were carried out on 2007 December 7 and 13 with exposure times of 6410 and 5450 seconds, respectively. The average count rate is 0.014±0.001 counts per second. All source photons were registered with energies below 1 keV and the spectrum is consistent with that of a supersoft X-ray source (SSS). The count rate and the spectrum are similar to the last X-ray observation taken on 2005 August 17 (Ness et al. 2007, astro-ph/0703286), The combined two spectra taken in 2007 can be fitted with a blackbody yielding kT=32±10 eV and NH=(4.2+1.9-1.1)1021 cm-2, leading to an observed X-ray flux (0.3-1keV) of 3.7 10-13 erg cm-2 s-1 which, at 6.5kpc distance, corresponds to a bolometric luminosity of 8 1037 erg s-1. Weak emission features may be present at energies corresponding to emission lines from NeIX, OVII, and NVII. The X-ray spectrum may be composed of continuum plus emission lines. We obtained UV magnitudes from UVOT for the December 13 observation and found 16.488±0.017 at 212nm (UVW2), 16.872±0.026 at 231nm (UVM2), and 16.289±0.015 at 291nm (UVW1), which corresponds to fluxes of (1.37±0.02)10-15, (8.10±0.02)10-17, and (1.21±0.02)10-17 erg s-1cm-2Å-1, respectively.