Gilles,
Some more info here:
http://www.history.navy.mil/download/ww2-30.pdf
Lt Alston was shot down in his F6F-5 Hellcat while attacking a transport convoy 5 mi. NE of Carcassonne at around 7 p.m.
As location Pennautier is mentioned elsewhere.
Another website says a/c number was # 18 or rather BuNo 58300.
Regards,
Leendert