next previous
Up: Optimizing ISOCAM data processing redundancy


   
Appendix B: LTT error determination

The error on the LTT correction is estimated using the standard deviation constructed with all the pixel pairs used to compute $\Delta(t)$. The offset correction is based on Eq. (4). For a pixel pair (( $\alpha, \delta, t_i$) and ( $\alpha, \delta, t_j$)) that have seen the same sky at different time, the offset at time ti is given by:

\begin{displaymath}\begin{array}{ll}
\Phi(\alpha, \delta, t_i, t_j) = &
F(\alph...
...{\Delta(t_j)}{F(\alpha, \delta, t_j)} \right]\cdot
\end{array}\end{displaymath} (B1)

We have evaluated the statistical error on the offset correction $\Delta(t_i)$:

\begin{displaymath}\sigma(t_i) = \sqrt{\frac{1}{n(n-1)}
\sum_{\alpha, \delta, t_{j\cap i}}(\Delta(t_i) - \Phi(\alpha, \delta, t_i, t_j))^2}
\end{displaymath} (B2)

where n is the number of pixel pairs.


next previous
Up: Optimizing ISOCAM data processing redundancy

Copyright The European Southern Observatory (ESO)