code: def getskyimg(self,chip):
          
          sci_chip = self._image[self.scienceExt,chip]
          skyimg = np.ones(sci_chip.image_shape,dtype=sci_chip.image_dtype)*sci_chip.subtractedSky
          if sci_chip._conversionFactor != 1.0: # If units are not already ELECTRONS
              skyimg *= self.getexptimeimg(chip)
          return skyimg
docs: Notes
          =====
          Return an array representing the sky image for the detector.  The value
          of the sky is what would actually be subtracted from the exposure by
          the skysub step.
  
          :units: electrons