, reveal what appear to be bright electrical phenomena flashing

A San Francisco amateur astronomer who photographs the space shuttles whenever their orbits carry them over the Bay Area has captured five strange and provocative images of the shuttle Columbia just as it was re-entering the Earth's atmosphere before dawn Saturday.

The pictures, taken with a Nikon 8 camera on a tripod, reveal what appear to be bright electrical phenomena flashing around the track of the shuttle's passage, but the photographer, who asked not to be identified, will not make them public immediately.

"They clearly record an electrical discharge like a lightning bolt flashing past, and I was snapping the pictures almost exactly . . . when the Columbia may have begun breaking up during re-entry," he said.

The photographer invited The Chronicle to view the photos on his computer screen Saturday night, and they are indeed puzzling.

They show a bright scraggly flash of orange light, tinged with pale purple, and shaped somewhat like a deformed L. The flash appears to cross the Columbia's dim contrail, and at that precise point, the contrail abruptly brightens and appears thicker and somewhat twisted as if it were wobbling.

"I couldn't see the discharge with own eyes, but it showed up clear and bright on the film when I developed it," the photographer said. "But I'm not going to speculate about what it might be."

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