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On Sun, 16 Feb 2003, Taichi Kato wrote: > project was undertaken with a 10cm (4-inch) telescope. With an impetutous > training, Hasegawa-san became able to visually track symbiotic stars down > to 16-th mag with this telescope (a persuit for a better limiting magnitude This is not possible. Studies have shown that a minimum of 90 quanta incident upon the fully dark adapted human eye is the threshold of detectability (with optimum target size and flash duration). This corresponds to a magnitude of 7.6 for a Vega type star just detectable with a fully wide 7mm iris. Which becomes magnitude 13.4 for a 4" aperture. If he is detecting magnitude 16, that is 11x fainter than the limit and corresponds to about 8 quanta incident on the eye. About 10% of those actually get through to be detected by the rod cells, so in fact statistically even less than 1 quanta is getting "detected"! Thats just not possible because a minimum of 5-9 quanta are needed for the retina to respond. Thats the way it is physiologically "wired", for optimum dark signal/noise. If the retina responded to single quanta the background would be too noisy for effective imaging in the brain, and this guy would have been stumbling around in the dark. Mike Linnolt
Return to the Powerful Daisaku Nogami
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