FIRST OFF . . .

Ted Kopppel’s 90-minute interview with Democratic presidential candidate Gov. Michael Dukakis of Massachusetts on Tuesday night on ABC’s “Nightline” scored well in the ratings. According to A.C. Nielsen’s overnight ratings in the nation’s 16 biggest TV markets, “Nightline” received a rating of 9.2 and a 31% share of the audience for the 90 minutes. (Each rating point equals 904,000 households with televisions. The share is a percentage of sets in use.) NBC’s “The Tonight Show” and the first half-hour of “Late Night With David Letterman” received a rating of 4.8 and a 16 share. The CBS show “Nightheat” and the first half hour of “The CBS Late Show” got a 4.6 rating and 15 share.