Stargate SG-1‘s on again, off again love affair with the Nielsen ratings is back on, with the series finale winning strong viewership numbers for SCI FI Channel. The heavily promoted (or should we say promoted) episode “Unending” scored a 1.7 rating, about 50 percent higher than its recent numbers.

This represents 2.2 million viewers for the swan song of the veteran series.

“Unending” made SCI FI Channel the number one cable channel among the 18 to 49 and 25 to 54 demographics at the 8 p.m. hour, and even beat broadcast networks FOX, CBS and ABC among men 25 to 54 and 18 to 49.

It is the show’s highest rating since the mid-season finale “The Quest, Part 1,” and for Season Ten second only to the more heavily promoted two-hundredth episode (1.9).

Season finale night (June 22, 2007) also proved big for Stargate Atlantis, which followed with a 1.5 rating at 9 p.m., SCI FI announced. With almost 2 million viewers, “First Strike” turned in the spin-off show’s srongest ratings since the mid-season finale “The Return, Part 1” (1.6).

Painkiller Jane finished the night with a 1.0 rating at 10 p.m., the show’s best performance in key demographics since its premiere on April 13.

SCI FI also recently announced ratings for episodes 17 and 18 of the current season, demonstrating just how big the finale bump is. Both “Talion” and “Sunday” earned 1.1 ratings on June 1. “Family Ties” and “Submersion” both did a little better on June 8, with ratings of 1.2.

Only the June 15 ratings numbers have yet to be released, and should be available this coming Monday along with the final season averages and our wrap-up ratings report.

Season Four of Stargate Atlantis is now in production for a fall premiere. We know how nice it is outside this time of year, but don’t miss GateWorld’s continuing coverage and brand new cast and crew interviews throughout the summer!

(Thanks to Morjana, Ron, Platschu, and VisitEureka.net for contributing)