docs: def get_pixel_coordinates(self, point, ccdnum):
          """
          Retrieves the pixel location of a point within the current HDUList given the
          location in the original FITS image.  This takes into account that
          the image may be a cutout of a larger original.
  
          Args:
            point: tuple(float, float)
              (x, y) in original.
  
          Returns:
            (x, y) pixel in this image.
            @param extno: the extno from the original Mosaic that the x/y coordinates are from.
          """
          hdulist_index = self.get_hdulist_idx(ccdnum)
          if isinstance(point[0], Quantity) and isinstance(point[1], Quantity):
              pix_point = point[0].value, point[1].value
          else:
              pix_point = point
          if self.reading.inverted:
              pix_point = self.reading.obs.naxis1 - pix_point[0] +1 , self.reading.obs.naxis2 - pix_point[1] + 1
  
          (x, y) = self.hdulist[hdulist_index].converter.convert(pix_point)
          return x, y, hdulist_index