Taylor, P.; Beardmore, A. P.; Norton, A. J.; Osborne, J. P. and Watson, M. G.
GINGA and ROSAT observations of AO PSC and V1223 SGR.
Monthly Notices of the Royal Astronomical Society, 289(2) pp. 349–354.
We present results from X-ray observations of the intermediate polars AO Psc and V1223 Sgr, taken with the ROSAT HRI and the Ginga LAC. Both sources show sinusoidal modulation at the white dwarf spin period in all energy bands, possibly with the exception of the highest. The depths of these modulations increase at lower energy, but the rates at which they do so are not consistent with single column densities of absorbing material. Neither source shows any significant pulse at the beat period, which argues for a predominantly disc-fed accretion model in each case. The AO Psc observations show a modulation at the orbital period, which in the ROSAT data may indicate an extended absorbing structure, with a dip at orbital phase ~0.5-0.8 superimposed. The V1223 Sgr ROSAT data show short dips which occur intermittently at around orbital phase 0.8. These dips vary in duration and phase of commencement and suggest that the system inclination angle is just sufficient for our line of sight to graze the upper extent of the material thrown out of the disc plane.
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