The Sensex at the Bombay Stock Exchange gained 137 points, or 0.7 percent, to close at 19,517, on Tuesday , with sentiment boosted by the lower-than-expected quarterly current account deficit, and encouraging auto sales in September. The Nifty at the National Stock Exchange rose 45 points, or 0.8 percent, to 5,780.Stock markets in Japan, South Korea and Singapore gained between 0.1 percent and 0.4 percent.