NV: If the scratch does NOT catch on your finger nail, you could try some Jewellers Rouge (try your local glass shop for availability). Mix with water to make a paste and rub into the scratch.
Another option that I have not tried personally, but have seen discussed on other forums is the glass repair kit from Janvil:
One Grand makes a glass/cleaner polish. It is formulated to remove waterspots and fallout. You can apply it with an orbital buffer. It might be abrasive enough to remove light scratches.