\name{sunspot}
\alias{sunspot}
\alias{sunspot.month}
\alias{sunspot.year}
\title{
  Yearly Sunspot Data, 1700--1988.
  Monthly Sunspot Data, 1749--1997.
}
\usage{
data(sunspot)
}
\format{
  The univariate time series \code{sunspot.year} and
  \code{sunspot.month} contain 289 and 2988 observations, respectively.
  The objects are of class \code{"ts"}.
}
\description{
  Monthly and yearly number of sunspots. 
}
\seealso{
  \code{sunspot.month} is a longer version of \code{\link{sunspots}}
  in base \R, that runs until 1988.
}
\source{
  Monthly data: Sunspot Index Data Center,
  World Data Center-C1 For Sunspot Index
  Royal Observatory of Belgium, Av. Circulaire, 3, B-1180 BRUSSELS
  \url{http://www.oma.be/KSB-ORB/SIDC/sidc_txt.html}

  Yearly data: H. Tong (1996)
  \emph{Non-Linear Time Series}. Clarendon Press, Oxford, p. 471. 
}
\examples{
## Compare the monthly series from 'base' and 'ts':
data(sunspots, package = base)
data(sunspot,  package = ts)
plot (sunspot.month, main = "sunspot.month [ts]", col = 2)
lines(sunspots)# ``very barely'' see something

## Now look at the difference :
all(tsp(sunspots)     [c(1,3)] ==
    tsp(sunspot.month)[c(1,3)]) ## Start & Periodicity are the same
n1 <- length(sunspots)
table(eq <- sunspots == sunspot.month[1:n1]) #>  132  are different !
i <- which(!eq) 
rug(time(eq)[i])
s1 <- sunspots[i] ; s2 <- sunspot.month[i]
cbind(i = i, sunspots = s1, ss.month = s2,
      perc.diff = round(100*2*abs(s1-s2)/(s1+s2), 1))
}
\keyword{datasets}


