NORTHAMPTON — On Sept. 12, some talented artists will be able to chalk their successes up to, well, chalk. The Northampton Chalk Art Festival returns to Arts Night Out that day, with nine artists competing for prizes of $250, $150, and $100. The prizes will be awarded by a panel of judges for the top three creations. This will be the fifth iteration of the festival, which began in 2010. The nine artists were chosen by a juried process and will each receive a $100 stipend.