The prequel to “Battlestar Gallactica,” a new series called “Caprica,” got off to a stumbling start in the ratings last week.

Only about 1.6 million viewers tuned into the show’s first episode — calling into question the Syfy channel’s decision to make the debut show widely available online and on DVD for several weeks before the premiere.

Syfy estimated that about 2 million viewers saw the show before its TV debut last Friday, eating deeply into the opening-night audience.