model{
  ## Likelihood ##
  for( j in 1:Nbobs ) {
    M[j] ~ dnorm(theta[j], prec.obs[j])
    prec.obs[j] <- 1/(s[j]*s[j])
  } 
  
  ## Prior distribution of the dates of interest ##   
  for (i in 1:Nbobs) { 
    tt[i] ~ dunif(ta,tb) 
  }
  theta = sort(tt) 
  
}