Persistent similar to 1 Hz quasi-periodic oscillation in the dipping low-mass X-ray binary 4U 1323-62

We have discovered a similar to 1 Hz quasi-periodic oscillation (QPO) in th e persistent emission, the dips, and the type I X-ray bursts of the low-mas s X-ray binary 4U 1323-62. The rms amplitude of the QPO is approximately 9% , only weakly depending on photon energy. The amplitude is consistent with being constant throughout the persistent emission, the dips, and the bursts in all but one observation, where it is much weaker during one dip. These properties suggest that we have observed a new type of QPO, which is caused by quasi-periodic obscuration of the central X-ray source by a structure i n the accretion disk. This can only occur when the binary inclination is hi gh, consistent with the fact that 4U 1323-62 is a dipping source. The quasi -periodic obscuration could take place by partial covering of an extended c entral X-ray source by a near-opaque medium or by covering of a point sourc e by a medium having suitable characteristics to produce the relatively ene rgy-independent oscillations.