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Steven T. Myers edited subsubsection_Survey_Speed_label_sec__.tex
almost 8 years ago
Commit id: 83a8aa17752686be81608fd1aaa719f7fe94466a
deletions | additions
diff --git a/subsubsection_Survey_Speed_label_sec__.tex b/subsubsection_Survey_Speed_label_sec__.tex
index 4f169c3..0914caa 100644
--- a/subsubsection_Survey_Speed_label_sec__.tex
+++ b/subsubsection_Survey_Speed_label_sec__.tex
...
\bar{\Omega}_B = { \sum_k w_k \Omega_{Bk} \over \sum_k w_k }
\end{equation}
where for uniform weights $w_k=$const.\ and uniform frequency coverage over the band we can approximate by the integral
\begin{eqnarray} \begin{equation}
\bar{\Omega}_B
& =
& {1\over \nu_{max}-\nu_{min}}\,\int_{\nu_{min}}^{\nu_{max}}
d\nu\,\Omega_B(\nu)
\qquad d\nu\,\Omega_B(\nu).
\end{equation}
Assuming the beam FWHM scales inversely by frequency, then
\bar{\Omega}_B = {\nu^2_0 \over \nu_{min}\,\nu_{max}}\,\Omega_B(\nu_0)
\qquad\qquad \Omega_B(\nu) = \Omega_B(\nu_0)\,\left( {\nu_0 \over \nu}\right)^2
\\
& = & {\nu^2_0 \over \nu_{min}\,\nu_{max}}\,\Omega_B(\nu_0)
\end{eqnarray}
assuming \end{equation}
or equivalently $\bar{\Omega}_B =\Omega_B(\bar{\nu})$ where $\bar{\nu}=\sqrt{\nu_{min}\,\nu_{max}}$ is the
beam FWHM scales inversely by geometric mean frequency. For full S-band $\nu_{min}=$2GHz, $\nu_{max}=$4GHz, and $\nu_{0}=$3GHz then
\begin{equation}\label{eq:ombeff}
\bar{\Omega}_B= {9\over8}\,\Omega_B(\nu_0=3{\rm GHz})
\qquad \qquad\qquad \bar{\theta}_P = \sqrt{9\over8}\,\theta_P(3{\rm GHz})
\end{equation}
(this holds for any 2:1 band relative to the mid-band FWHM).