ABC’s “The Astronaut Wives Club” launched in unspectacular fashion Thursday, faring OK by low-bar summer standards but still finishing behind an hour of repeat CBS comedies and and newsmagazine “Dateline” on NBC.

According to preliminary national estimates from Nielsen, “Astronaut Wives Club” averaged a 1.1 rating/4 share in adults 18-49 and 5.5 million viewers overall from 8 to 9 p.m., putting it on par with NBC’s bow of “Aquarius” in May and a tick above where Fox’s “Wayward Pines” bowed earlier in the month. ABC did better on June 1 with the premiere of “The Whispers” (1.5 rating in 18-49, 5.66 million viewers overall), though it benefited from a sizable lead-in courtesy of “The Bachelorette.” In a positive sign for the show, it was up in its second half-hour in just about every category.

Period dramas have been a tough sell for audiences over the years, and they tend to skew older than other hourlongs. “Astronaut Wives Club,” which was originally scheduled to air in the 2013-14 season and then pushed back on two occasions, did a slightly better 5 share (1.5 rating) in adults 25-54 and fared best among women 25-54 (2.2 rating/7 share). Perhaps benefiting from promotion during the NBA Finals, it skewed a little more male than ABC’s recent Thursday dramas, with 33% of its 18-49 and 25-54 audience comprised of men.

“Astronaut’s Wives Club” was followed by the two-hour season premiere of “Mistresses” (0.9/3 in 18-49, 3.8 million viewers overall), which was down 0.2 from its season opener of last year when it aired on Mondays. It finished ahead of golf on Fox and original dramas on NBC, and equaled the 18-49 rating for CBS repeats from 9 to 11. As was the case when it aired behind “The Bachelorette” last summer, “Mistresses” had a very female skew (71% of its 18-49 audience).

NBC opened well with “Dateline” (1.3/5 in 18-49, 6.3 million viewers overall), which recorded its top rating since April 2 (tied with CBS comedy repeats for the 8 p.m. lead in 18-49) and won outright in total viewers. It was followed by “Aquarius” (0.7/3 in 18-49, 3.4 million viewers overall), which was down a tenth from last week, and “Hannibal” (0.5/2 in 18-49, 1.8 million viewers overall), which held steady overall while surging in all male demos vs. last week’s episode opposite the NBA Finals on ABC.

For CBS, a repeat of “The Big Bang Theory” (1.5/7 in 18-49, 7.1 million viewers overall) was the night’s No. 1 series in 18-49. It was followed by encores of “The Odd Couple” (1.1/4 in 18-49, 5.1 million viewers overall), “Mom” (1.1/4 in 18-49, 5.5 million viewers overall), “Mike & Molly” (1.1/4 in 18-49, 5.5 million viewers overall) and “Elementary” (0.8/3 in 18-49, 4.2 million viewers overall).

Golf’s U.S. Open moved to primetime in its first year on Fox, so it was able to show some nice ratings improvement even if the event wasn’t much of a ratings factor relative to the other broadcast networks on Thursday night. Fox’s stations averaged a 0.7/3 in 18-49 and 2.9 million viewers overall from 8 to 11 p.m., with these numbers subject to revision since they don’t accurately reflect West Coast viewing. In Nielsen’s metered-market overnights, the U.S. Open averaged a 2.4 rating, which was up 71% over last year’s 1.4 on NBC when it aired in the lower-viewed 3-5 p.m. ET window.

From noon to 8 p.m. ET, cable network Fox Sports 1 averaged a 1.28 overnight household rating — up 20% from last year’s 1.07 on ESPN for coverage that aired from 9 a.m. to 3 p.m. ET, and then resumed from 6 to 7 p.m. ET.

At CW, “Beauty and the Beast” (0.3/1 in 18-49, 0.9 million viewers overall) was even with last week, followed by a repeat “The Vampire Diaries” (0.2/1 in 18-49, 0.6 million viewers overall).

Preliminary 18-49 averages for the night: CBS, 1.1/4; ABC and Univision, 0.9/3; NBC, 0.8/3; Fox, 0.7/3; Telemundo, 0.5/2; CW, 0.2/1.

In total viewers: CBS, 5.3 million; ABC, 4.4 million; NBC, 3.8 million; Fox, 2.9 million; Univision, 2.4 million; Telemundo, 1.2 million; CW, 0.8 million.