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Дата изменения: Fri Feb 23 14:03:52 1996 Дата индексирования: Tue Oct 2 17:26:57 2012 Кодировка: Поисковые слова: martian surface |
The command does a series of tests on a catalogue of flat frames. The flat fields in the catalogue should be grouped in pairs with the same exposure time. Most ideally, one should be two groups of 8 frames each - the first with increasing exposure times and the second with decreasing exposure times, interleaved with those of the first group. In this way, tends observed in the CCD response that are probably caused by the effect of temperature variations on the light source can be rejected.
The command requires a value for the mean bias level and the standard deviation in the keywords BIASMEAN and BIASSIGM to be filled and hence should be executed after the command TESTB/CCD. If no value or the value zero is found no bias offset will be subtracted. The command produces: