how to make svg animation scaling around a center of a figure?

I'm trying to pulsate a star by using animateTransform with type="scale", but instead of scaling around a center of the star, it scales to left and down. How to scale the star around the center?

Svg code:

<svg version="1.1" id="star" xmlns="http://www.w3.org/2000/svg" x="170px" y="385px" width="100px" height="100px" viewBox="0 0 60 60" xml:space="preserve">
    <g>
        <polygon fill="#DAC978" points="18.832,36.694 5.903,25.156 23.146,23.419 30.125,7.557 37.104,23.419 54.347,25.155 41.417,36.694 45.095,53.629 30.125,44.898 15.155,53.63" />
        <path fill="#A58144" d="M30.125,13.765l4.104,9.327l1.175,2.669l2.901,0.292l10.139,1.021l-7.603,6.785L38.665,35.8l0.618,2.851 l2.162,9.957l-8.801-5.134l-2.519-1.469l-2.52,1.469l-8.803,5.134l2.162-9.957l0.619-2.85l-2.175-1.942l-7.603-6.785l10.139-1.021 l2.901-0.292l1.174-2.669L30.125,13.765 M30.125,1.35l-8.681,19.729L0,23.237l16.08,14.352l-4.574,21.063l18.62-10.858 l18.618,10.858L44.17,37.589l16.081-14.352l-21.445-2.159L30.125,1.35L30.125,1.35z" />
        <animateTransform 
            attributeType="xml"
            attributeName="transform"
            type="scale"
            from="0"
            by="1"
            dur="1s" 
            repeatCount="10"
        />

    </g>
</svg>

jsFiddle with working code.

Solution

animateTransform type scale seems to scale always from origin at (0, 0). One possible solution can be in translating your polygon so that its center is in (0, 0).

Here is working jsFiddle example.

Changes made to your original code:

The viewbox is changed from viewBox="0 0 60 60" to viewBox="-30 -30 60 60" in order to have center of the viewBox at (0, 0) (for more on viewBoxes you can see this tutorial)
polygon and path are grouped and then translated so that their center is at (0, 0) too:
```
<g transform="translate(-30,-30)">
    <polygon ... />
    <path ... />
</g>
```