A number of startups have been analysing tweets to gauge social popularity of TV shows for some time. Now Twitter is getting in on the action through a partnership with Nielsen.

The two companies are launching something called Nielsen Twitter TV Rating in the US: “a syndicated-standard metric around the reach of the TV conversation on Twitter” that will make its debut in Autumn 2013.

With 140m active users posting 1bn tweets every two and a half days, Twitter sees itself as an important source of data for online (and mobile) buzz around TV shows. Not the only one though: if Nielsen wanted a truly authoritative rankings system, it would need to add Facebook into the mix too.

Still, both Twitter and Nielsen think the new chart will help convince more broadcasters to launch “second-screen experiences” for their shows, and more advertisers to invest in what Nielsen’s Steve Hasker describes as “integrated ad campaigns that combine paid and earned media”.

CBS’ chief research officer David Poltrack is quoted in the announcement on the role of mobile devices in all this.

“The proliferation of smartphones and tablets has generated a substantial ‘connected’ TV audience that is simultaneously watching television and accessing the Internet through these devices,” he says, adding that CBS is already working with Nielsen and Twitter “in a program of research and experimentation” in second-screen features.