'Tuple defining the default ``bounding_box`` limits in each dimension,
``((y_low, y_high), (x_low, x_high))``
The default offset from the mean is 5.5-sigma, corresponding
to a relative error < 1e-7. The limits are adjusted for rotation.
Parameters
factor : float, optional
The multiple of `x_stddev` and `y_stddev` used to define the limits.
The default is 5.5.
Examples
>>> from astropy.modeling.models import Gaussian2D
>>> model = Gaussian2D(x_mean=0, y_mean=0, x_stddev=1, y_stddev=2)
>>> model.bounding_box
((-11.0, 11.0), (-5.5, 5.5))
This range can be set directly (see: `Model.bounding_box
<astropy.modeling.Model.bounding_box>`) or by using a different factor
like:
>>> model.bounding_box = model.bounding_box(factor=2)
>>> model.bounding_box
((-4.0, 4.0), (-2.0, 2.0))'

def bounding_box(self, factor=5.5):

    a = (factor * self.x_stddev)
    b = (factor * self.y_stddev)
    theta = self.theta.value
    (dx, dy) = ellipse_extent(a, b, theta)
    return (((self.y_mean - dy), (self.y_mean + dy)), ((self.x_mean - dx), (self.x_mean + dx)))
