We have examined images from the Precision Solar Photometric Telescope ( PSPT ) at the Mauna Loa Solar Observatory ( MLSO ) in search of latitudinal variation in the solar photospheric intensity .
Along with the expected brightening of the solar activity belts , we have found a weak enhancement of the mean continuum intensity at polar latitudes ( continuum intensity enhancement \sim 0.1 - 0.2 \% corresponding to a brightness temperature enhancement of \sim 2.5 { K } ) .
This appears to be thermal in origin and not due to a polar accumulation of weak magnetic elements , with both the continuum and CaIIK intensity distributions shifted towards higher values with little change in shape from their mid-latitude distributions .
Since the enhancement is of low spatial frequency and of very small amplitude it is difficult to separate from systematic instrumental and processing errors .
We provide a thorough discussion of these and conclude that the measurement captures real solar latitudinal intensity variations .