Because of the development of large-format , wide-field cameras , microlensing surveys are now able to monitor millions of stars with sufficient cadence to detect planets .
These new discoveries will span the full range of significance levels including planetary signals too small to be distinguished from the noise .
At present , we do not understand where the threshold is for detecting planets .
MOA-2011-BLG-293Lb is the first planet to be published from the new surveys , and it also has substantial followup observations .
This planet is robustly detected in survey+followup data ( \Delta \chi ^ { 2 } \sim 5400 ) .
The planet/host mass ratio is q = 5.3 \pm 0.2 \times 10 ^ { -3 } .
The best fit projected separation is s = 0.548 \pm 0.005 Einstein radii .
However , due to the s \leftrightarrow s ^ { -1 } degeneracy , projected separations of s ^ { -1 } are only marginally disfavored at \Delta \chi ^ { 2 } = 3 .
A Bayesian estimate of the host mass gives M _ { L } = 0.43 ^ { +0.27 } _ { -0.17 } M _ { \odot } , with a sharp upper limit of M _ { L } < 1.2 M _ { \odot } from upper limits on the lens flux .
Hence , the planet mass is m _ { p } = 2.4 ^ { +1.5 } _ { -0.9 } M _ { Jup } , and the physical projected separation is either r _ { \perp } \simeq 1.0 AU or r _ { \perp } \simeq 3.4 AU .
We show that survey data alone predict this solution and are able to characterize the planet , but the \Delta \chi ^ { 2 } is much smaller ( \Delta \chi ^ { 2 } \sim 500 ) than with the followup data .
The \Delta \chi ^ { 2 } for the survey data alone is smaller than for any other securely detected planet .
This event suggests a means to probe the detection threshold , by analyzing a large sample of events like MOA-2011-BLG-293 , which have both followup data and high cadence survey data , to provide a guide for the interpretation of pure survey microlensing data .