deletions | additions       diff --git a/subsection_Calibration_Scans_and_Overhead__.tex b/subsection_Calibration_Scans_and_Overhead__.tex  index 7e7d007..aba8195 100644  --- a/subsection_Calibration_Scans_and_Overhead__.tex  +++ b/subsection_Calibration_Scans_and_Overhead__.tex 
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\end{center}  \end{table}  foo The fixed flux and polarization calibration plus the first gain calibration scan in our simple model above provides a "fixed" calibration (FCAL) baseline. Assuming a single leakage scan on an unpolarized source, this is nominally 30min using the assumptions above, but could be in the range 20--36m. This gives a fixed overhead depending on block duration (or total duration sharing the same fixed calibration). These are tabulated in Table~\ref{tab:overheadFCAL}.  \begin{table}[h]  \begin{center}  \caption{\label{tab:overheadFCAL}Fixed overheads for various assumed fixed calibration (FCAL) durations $T_{FCAL}$. ``Block Duration'' refers to the length of a single self-contained SB or the sum of SB lengths that can share a single fixed calibration.}  \begin{tabular}{ccccc}  {\bf Block Duration (hrs)} & {\bf FCAL OH (20m)} & {\bf FCAL OH (25m)} & {\bf FCAL OH (30m)} & {\bf FCAL OH (36m)} \\  4.0 & 9.1\% & 11.6\% & 14.3\% & 17.6\% \\  6.0 & 5.9\% & 7.5\% & 9.1\% & 11.1\% \\  8.0 & 4.3\% & 5.5\% & 6.7\% & 8.1\% \\  10.0 & 3.4\% & 4.3\% & 5.3\% & 6.3\% \\  12.0 & 2.9\% & 3.6\% & 4.3\% & 5.3\% \\  18.0 & 1.9\% & 2.4\% & 2.9\% & 3.4\% \\  24.0 & 1.4\% & 1.8\% & 2.1\% & 2.6\% \\  \end{tabular}  \end{center}  \end{table}  In the VLASS proposal and TIP sent for review, the ALL-SKY component was assumed to incur an overhead of 17\%. This suggests that for inserting a gain calibrator every 30m that we want to have a total block length (observed for a single calibration) of 8 hours or more if we can reduce the OTF OH to 3.3\% or less, or 18 hours or more if we are limited to OTF OH of 6.6\%. If we observe in self-contained 4 hour blocks and gain calibrate every 20m then the overhead will be 30.5\% even for 3.3\% OTF OH, or if we desire to reduct this to 17\% overall then we need a calibration overhead of 13.3\% or a total of 28 min, and the fixed calibration scans plus slew must be done in 16m instead of 30m (very difficult) if we spend 90s per calibrator (instead of 2m). Thus, sharing calibration between multiple 4-hour SB is highly desirable.