The rain data has 366 real valued binomial responses
representing days on which it rained over the course of two years in
Tokyo.
y, the repsonse representing
the number of times it has rained on the ith day of the year in
Tokyo from 1983 through 1984, X, a matrix of ones, and
n, the number of observations for each day. n is two
for all days except Feb. 29. This is the famous Tokyo rainfall data from Kitagawa (1987).
Genshiro Kitagawa. Non-Gaussian State-Space Modeling of Non-stationary Time Series. Journal of the American Statistical Association (1987).