UPDATE: Sun News Network went off the air at 5 a.m. ET Friday after failing to find a new owner. Click here for the latest updates on this story.

Sun News Network is about to sign off, permanently. CBC News has learned that the cable news television channel will shut down early Friday.

The network began broadcasting in April 2011, launching a right-of-centre programming schedule, but it has had a constant challenge attracting viewers.

Its supporters blamed the CRTC for not giving it the same access enjoyed by news channels operated by CBC and CTV.

The federal broadcast regulator denied Sun News a guaranteed spot on basic cable TV packages in August 2013.

Data released as part of that application showed that while the network was available to 5.1 million households, it was only attracting, on average, 8,000 viewers at any given time.

That number was far lower than what well-established all-news networks operated by CTV and CBC were reporting. CBC, for example, said it had eight times as many viewers as Sun News.

When Quebecor launched the station, media pundits quickly dubbed it "Fox News North."

On the first day of broadcasting, Ezra Levant, one of the most controversial hosts of Sun News, showed the Danish cartoons of the Prophet Muhammad to TV viewers.

When Postmedia announced last October that it was buying Quebecor's Sun Media Corp. and its 175 English-language newspapers — including the Toronto Sun — the TV channel was not included in the deal.

Almost 200 people are employed at Sun News.