docs: def GetDetectorPSD(detectorName, LIGO3FLAG=0):
      """ GetDetectorPSD - function to return the PSD of the detector described by
  	detectorName.
  
  	detectorName - Name of required GW IFO.  Can be 'H1', 'L1', 'V1', 'I1',
                         or 'K1'.
  	LIGO3FLAG - Set to 1 to use LIGO3 PSD instead of aLIGO PSD for H1, L1
          and I1 detectors.
  
  	Returns PSD - the noise PSD for the detector described by detectorName.
  
          Sarah Gossan 2012. Last updated 02/18/14. """
  
      # H1, L1 or I1 - use aLIGO ZERODET_HIGHP configuration (fLow = 9Hz)
      # Noise curve is super complicated so just load in PSD file for now
      if detectorName == 'H1' or detectorName == 'L1' or detectorName == 'I1':
          if LIGO3FLAG:
              # Read in PSD
              PSD = np.loadtxt('LIGO3_PSD.txt')
          else:
              # Read in PSD
              PSD = np.loadtxt('ZERO_DET_high_P_PSD.txt')
  	# Only want second column of file
          PSD = PSD[:,1]
      # V1 - use analytical expression for AdVirgo (fLow = 10Hz)
      elif detectorName == 'V1':
          # Use analytical expression from arXiv:1202.4031v2
  	x = np.linspace(0,N_fd-1,num=N_fd)*dF/300.
          x[0] = x[1] # Not going to use f=0Hz component anyway, but this stops 
  		    # the log fn complaining
  	x = np.log(x)
  	xSq = x*x
       	asd = 1.259e-24*(0.07*np.exp(-0.142 - 1.437*x + 0.407*xSq) + \
                           3.1*np.exp(-0.466 - 1.043*x - 0.548*xSq) + \
                           0.4*np.exp(-0.304 + 2.896*x - 0.293*xSq) + \
                           0.09*np.exp(1.466 + 3.722*x - 0.984*xSq))
          PSD = asd**2 
      # K1 - use analytical expression for KAGRA (fLow = 10Hz) 
      elif detectorName == 'K1':
  	# Use analytical expression from arXiv:1202.4031v2
  	x = np.linspace(0,N_fd-1,num=N_fd)*dF/300.
          x[0] = x[1] # Not going to use f=0Hz component anyway, but this stops 
                      # the log fn complaining
          x = np.log(x)
          xSq = x*x
  	asd = 6.499e-25*(9.72e-9*np.exp(-1.43 - 9.88*x - 0.23*xSq) + \
  		    	 1.17*np.exp(0.14 - 3.10*x - 0.26*xSq) + \
  			 1.70*np.exp(0.14 + 1.09*x - 0.013*xSq) + \
  			 1.25*np.exp(0.071 + 2.83*x - 4.91*xSq))
          PSD = asd**2
            
      return PSD