 
  
  
   
  
       
 
 
  Scattering
   Scattering   
  
 
  Dispersion
   Dispersion   
  
 
  
      
 
  Pulsar Spectral Index
   Pulsar Spectral Index   
  
 
  Young pulsars deep in Galactic plane
   Young pulsars deep in Galactic plane 
 
  Implies high frequency surveys
   Implies high frequency surveys   MHz
  MHz 

  
Figure 21: An example of a 1400 MHz survey. Filled circles are new pulsars,
Open circles are previously known pulsars. From Johnston et al 1992
[16]