2000AJ....119.1930C

We present coordinated Extreme Ultraviolet Explorer (EUVE) and Rossi X-Ray Timing Explorer (RXTE) target of opportunity observations of the 1998 August high state of AM Herculis. The EUVE light curve sampled phases ∼0.0-0.3 and ∼0.5-0.8 and showed AM Her to be uncharacteristically bright during these phases but lacking the expected counts at phase ~0.5, possibly because of absorption. The RXTE proportional counter array (PCA) 2-20 keV and HEXTE 15-60 keV light curves clearly show the 3.09 hr orbital modulation. No correlations between the soft and hard bands predicted in the simple one-pole accretion model were detected in the ~1600 s of true, simultaneous EUVE and RXTE data. Quasi-periodic oscillations (QPOs) of 1-3 s found in optical data for several magnetic cataclysmic variables were not detected in PCA high time resolution data of AM Her with a 90% confidence upper limit for the rms amplitude of 3%. No significant QPOs were detected in the 10s-100s of seconds range with EUVE or RXTE. The EUVE spectrum was well fitted with a 19 eV blackbody. The phase-averaged PCA spectrum was well fitted with a 17.6^+0.2_–0.4 keV thermal bremsstrahlung (TB) continuum plus a broad iron line centered at 6.5 keV and absorption edge at 9.2 keV. HEXTE detections extended to 100 keV and preferred a highly absorbed TB continuum with temperature of 37⁺⁹_–8 keV. The thermal bremsstrahlung plus emission-line (E_line=6.7 keV) and edge model fit to PCA spectra as a function of phase could be described as a single TB temperature of 18.9±0.2 keV with a variable column density of 7.1-53.5x10²¹ cm^–2 and did not require more complex continuum models. The ratio of EUV to X-ray luminosity showed no soft excess and was more in accord with the simple one-pole model than previous observations.