The content of extremely high energy (EHE) photons in the highest energycosmic rays can be investigated by analyzing showers arriving from directionswhere the perpendicular component of the Earth's magnetic field is high orshowers arriving from the region surrounding the Sun. We perform Monte Carlosimulations of cascades initiated by photons with parameters of the highestenergy showers observed by the past and present detectors (AGASA, Fly's Eye,Yakutsk, Haverah Park). The purpose is to find out which events should cascadewith high probability if initiated by photons. It is shown that EHE photonsarriving from directions towards the magnetic poles cascade with higherprobability. Alternatively, the lowest probabilities of cascading are expectedfor photons arriving from directions of the equator at the zenith angles equalto the angle between location of the specific observatory and the magneticpole. We show that very unusual showers should arrive from direction of the Sundue to cascading of photons in the Sun's magnetosphere if EHE photons arenumerous at the highest energies. The rate of such showers is estimated onabout one per ten years. However extraordinary lateral distribution ofsecondary particles of such showers in the Earth's atmosphere may help todistinguish them from the ordinary showers arriving isotropically from the sky.
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