Viewers in search of network newscasts of the opening night of the Republican National Convention will find repeats of “Castle” and “Hawaii Five-0” and an original “Grimm” instead. Network news has relegated all convention coverage to one hour a night at 9 p.m., beginning Tuesday. In their collective wisdom, they have decided to forgo the opening night entirely.

Are the networks abdicating their journalistic responsibility? Or merely acknowledging that viewers follow politics on cable and emerging media — when they watch it at all?

Cable coverage tonight of the Republican National Convention starts at 6 p.m. on CNN and will be folded into the regular lineup of prime-time shows on MSNBC and Fox News. PBS (7 p.m.) offers three hours of coverage. Current TV begins at 6 p.m. and includes observations from the network’s co-founder, former vice president and presidential candidate Al Gore, who has been to a few conventions.

Bloomberg television will offer convention insight on “Street Smart” (2 p.m.) and in prime time with “The Economy Election” (8 p.m.).

Viewers who choose to transcend television entirely can follow live feeds of the convention. ABC News Digital and YouTube have joined forces to offer live streams and archived footage of the convention. This service is available all day and night and brings convention coverage back to the old days of gavel-to-gavel broadcasts that allowed audiences to follow the nitty-gritty minutiae of party politics. Follow the action at www.youtube.com/politics?featureinp-bp-ype-01.

As it has for decades, C-SPAN will offer hours of convention footage. It also provides an Internet hub (www.c-span.org/RNC) for the Republican convention and will provide the same for the Democratic convention in September.

While networks offer fewer hours of convention newscasts than ever before, there has never been so much convention coverage, or so many ways to watch.

Tonight’s other highlights

• Ricky talks about wedding plans on “The Secret Life of the American Teenager” (7 p.m., ABC Family).

• A fatal auto wreck leaves few clear clues on “Major Crimes” (8 p.m., TNT).

• Hank needs help finding his daughter on “Grimm” (9 p.m., NBC).

• A case concerning a schizophrenic forces Pierce to take stock on “Perception” (9 p.m., TNT).