text: **12**
  
  **s**
  **e**
  **i**
  **r**
  **t**
  **n**
  **E**
  **10**
  
  **8**
  
  **6**
  
  **4**
  
  **2**
  
  **0**
  **−5** **−4** **−3** **−2** **−1** **0** **1** **2** **3** **4**
  **5**
  σ 
  
  Figure 1: (Left) The preliminary signiﬁcance measured from each of the 49 non-detected candidates using standard 
  analysis cuts. The curve shows a Gaussian distribution, with mean zero and standard deviation one, normalized to the 
  number of blazars. A similar result is obtained using analysis cuts optimized for soft-spectrum sources. (Right) The 
  distribution of ﬂux upper limits for the non-detected blazars in percentage of Crab Nebula ﬂux above the observation 
  threshold. The time-weighted average limit is less than ∼2% Crab ﬂux. 