Casey Law edited new.tex  almost 10 years ago

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\section{The Case for Completing Observing}  For an assumed intrinsic temporal width of 5 ms, completing the 147-hour 152-hour  project would give us roughly 126 hours on target and a 50\% chance at detecting an FRB. Prior to the downward revision in the fluence limit of \citet{2013Sci...341...53T}, we estimated had  a 50\% chance at detecting 3 FRBs.Discovering a lower inferred rate is frustrating, but we still feel that scientific payoff of an interfermetric detection justifies the effort of continued observing.  Even without a detection, any Any  constraint made defined  by this campaign will be the baseline upon which future observations can build. For example, a commensal, fast transient detection system could be fairly easily implemented for a 50 ms integration time to do the same FRB science at roughly 5 times higher flux limits. Constraints from that kind of observation would be more powerful when considered jointly with any VLA FRB project rate limit. Our revisions to the flux limits of published FRB surveys highlight the unique contribution of an interferometer to understanding FRBs. Previous single-dish work overlooked the fact that the beam gain at the half-power point was most relevant to defining overall sensitivity. This was obvious in our imaging tests, since we directly measured the sensitivity at each position in the beam. Furthermore, single-dish Single-dish  surveys typically quantify detections in SNR because it is inefficient to include end-to-end tests and flux calibration. The VLA FRB project builds these measurements in with modest overhead, giving us the ability to make robust constraints on the flux and rate of FRBs. New observations in D configuration will be more sensitive than existing B configuration observations, since our detection threshold is defined by the thermal noise in the images. Because each pixel in the image is independent, compact configurations produce images with fewer pixels and lower tail probabilities. This will allow us improve sensitivity by reducing our threshold from $8\sigma$ to $7.6\sigma$. The D configuration resolution of  50"beam  will localize any detection to a allow localization  precision better than 3\arcsec, two 3", more than 2  orders of magnitude more precisely better  than any other FRB localization. This should allow will give us  unique galaxy  associations toan  R-band depth depths  of 24.5, 24,  equivalent to a median  redshift of 0.6. 0.6 \citep{2002AJ....123.1111B}.  New observing will be computationally easy to support, since D configuration images are smaller. The processing time and memory footprint have been dominated by the FFT stage of imaging. In earlier B configuration imaging, the processing pipeline using 14 nodes at the AOC can search two hours of data in about 24 hours, equivalent to roughly 220 images per second per node or roughly $3\times10^3$ images per second. We estimate that processing of D configuration data will proceed roughly 3 times faster and will be easy to process on a daily cycle with a few nodes at the AOC cluster. We are working with James Robnett to use the batch submission system for our transient search pipeline. This will allow us to avoid a block reservation of nodes, yet keep up with our daily processing needs.