2003IAUC.8107....1S

S. Starrfield, Arizona State University; J.-U. Ness, Hamburg; J. J. Drake, Harvard-Smithsonian Center for Astrophysics; and M. Orio, University of Wisconsin, report, for a much larger collaboration, that they observed V4743 Sgr for 7 hr beginning at Mar. 19.396 UT with the Chandra X-ray satellite (+ Low Energy Transmission Grating Spectrometer + High Resolution Camera): "The spectrum is complex, dominated by continuum emission from 2.0 to 4.0 nm (peak around 2.8 nm) with obvious and deep absorption features. Assuming a blue shift of -2400 km/s, we tentatively identify C VI at 3.38 nm and O VII at 2.16 nm and are in the process of identifying other spectral features. Our spectrum (qualitatively, but not quantitatively) resembles the XMM-Newton spectrum of Cal 83 by Paerels et al. (2001, A.Ap. 365, L308). It appears that we are observing the hot atmosphere of the underlying white dwarf undergoing nuclear burning near the surface. This nova is bright at x-ray wavelengths, with a count rate of 40 counts/s plus large amplitude oscillations of 10 counts/s with a period of 1323 s (preliminary). There appear to be additional periods present in the data, suggesting that this might be a pulsation rather than rotation, and further analysis of the light curve is ongoing (see also Drake et al. 2003, Ap.J. 584, 448). Of further note in the light curve, after 3.6 hr a slow decay occurs; the counts drop to near zero after about 1.5 hr and remain near zero for the last 1.5 hr of the observation. We have a 36500-s XMM-Newton observation beginning at Apr. 4.921 and urge contemporaneous ground-based spectroscopic and photometric observations of this exciting nova."