... Even the sky measurements are not exactly proportional to the diaphragm area. ... should be removed; so it is a good idea to run the sky model, even if you decide not to subtract its calculated values from the ...
... Even the sky measurements are not exactly proportional to the diaphragm area. ... should be removed; so it is a good idea to run the sky model, even if you decide not to subtract its calculated values from the ...
... You may find that such observations cannot be corrected for sky by this method, if the star was measured during twilight, but the corresponding sky measurement occurs just after the end of evening twilight or just before the start of morning twilight. ...
... You may find that such observations cannot be corrected for sky by this method, if the star was measured during twilight, but the corresponding sky measurement occurs just after the end of evening twilight or just before the start of morning twilight. ...
... This is useful if there are no reasonable blank sky calibration frames and the astronomical exposures are evenly illuminated but the flat fields are not. ...
... Even a tiny cloud anywhere in the sky means you probably have ``incipient clouds'' (variable patches of haze) all over the sky, because of the layered structure of the atmosphere. ...
... Even a tiny cloud anywhere in the sky means you probably have ``incipient clouds'' (variable patches of haze) all over the sky, because of the layered structure of the atmosphere. ...