def getexptimeimg(self,chip):
        """
        Notes
        =====
        Return an array representing the exposure time per pixel for the detector.
        This method will be overloaded for IR detectors which have their own
        EXP arrays, namely, WFC3/IR and NICMOS images.

        :units:
          None

        Returns
        =======
        exptimeimg : numpy array
            The method will return an array of the same shape as the image.

        """
        sci_chip = self._image[self.scienceExt,chip]
        if sci_chip._wtscl_par == 'expsq':
            wtscl = sci_chip._exptime*sci_chip._exptime
        else:
            wtscl = sci_chip._exptime

        return np.ones(sci_chip.image_shape,dtype=sci_chip.image_dtype)*wtscl