fit to the noise curve in this paper. We reproduce in Fig. \[bsdfig\], the variation of errors in the parameters with the SNR as given in Figure 5 of [@BSD96] for the parameters $\tau_0$ and $t_a$, except that we use the log scale for both the axis, as is conventional in statistical literature. The continuous line represents the errors computed via the covariance matrix and in this approximation the errors are inversely propotional to the SNR. The dotted line represents the errors as obtained from the Monte Carlo simulations. The rest of this paper tries to explain the discrepancy between the two curves in this figure at low SNRs $\rho\approx10$.

The equation for the errors {#MCres2}
---------------------------

The expression for the Fourier transform of the chirp in eqn. (\[FT\]) in the new coordinates retains its form, but the functions $\chi_i(f)$ are now transformed to, $$\eta_i(f) = \sum\limits_{j=1}^3\chi_j \left[S^{-1}\right]^j_i.$$ Rewriting eqn. (\[m1\]) in the new parameters we have at $\nu^j=\hat\nu^j$, $$\label{m1nu}
\kappa_i = -\frac{1}{\check
A}\left\langle{\bf n}, \frac{\partial
{\bf h}}{\partial\nu^i}\right\rangle
= \left\langle{\bf h}(\check\nu^j), \frac{\partial
{\bf h}}{\partial\nu^i}\right\rangle.$$ Using the definition of the scalar product in eqn. (\[scal\]), we have, $$\label{kap2}
\kappa_i = 2 {\cal N}^2
\int_{0}^{\infty}\frac{f^{7/3}\eta_i(f)\sin(\sum\limits_{j=1}^3 
\eta_j(f)\Delta\nu^j)}{S_n(f)}df,$$ where $\Delta\nu^j = \hat\nu^j-\check\nu^j$. In the 