Abstract
We have studied the radiative properties of small photospheric magnetic elements during the rising phase of solar cycle 23 from 1996 to 2001, determining their contrasts as a function of heliocentric angle, magnetogram signal, and the solar cycle phase. Sorting the magnetogram signal into different ranges allowed us to distinguish between the contrast of different magnetic structures. We find that the contrast center-to-limb variation (CLV) of these small magnetic elements is independent of time with a 10% precision, when measured during the rising phase of solar cycle 23. The same techniques used to find activity can be used to remove activity and find the quiet Sun. For that we have examined images from the Precision Solar Photometric Telescope (PSPT) in search of latitudinal variation in the solar photospheric intensity predicted by differential rotation models. We found a weak enhancement of the mean continuum intensity at polar latitudes (continuum intensity enhancement ~0.1 - 0.2% corresponding to a brightness temperature enhancement of ~2.5 K). This appears to be thermal in origin and not due to a polar accumulation of weak magnetic elements.