Документ взят из кэша поисковой машины. Адрес оригинального документа : http://hea-www.harvard.edu/~saku/Telescope.pdf Дата изменения: Tue Mar 1 20:51:47 2011 Дата индексирования: Mon Oct 1 20:57:52 2012 Кодировка:

Basic observing:
Sky flats==twilight flats. Good because get uniform light. Bad because very short time available to obtain. Also may get stars within the field; for this do several different sky patches and take the mode or median. Dome flats. Good because can take anytime. Bad because sometimes illumination is not good enough (Saku question: what is good?). Dome flats scale by integration time. Lamps for wavelength calibrations frequently. Acquire object frequently. Sky flats==twilight flats. Good because get uniform light. Bad because very short time available to obtain. Also may get stars within the field; for this do several different sky patches and take the mode or median. Dome flats. Good because can take anytime. Bad because sometimes illumination is not good enough. Dome flats scale by integration time. Lamps (He, Ne, Ar) for wavelength calibrations frequently. Acquire object frequently.