Corrections and Clarifications
In the report "The drift of Saturn's north polar spot observed by the Hubble Space Telescope" by J. Caldwell et al. (16 Apr., p. 326), the revised System III rotation rate of the drift was incorrectly calculated. It should not have been "810.737° ± 0.008° per day," as stated (line 21, col. 1, p. 329), but rather "810.851° ±0.008° per day."