An average of at least 80 million people were at home glued to their television sets each minute of the evening of Sept. 11, watching prime-time coverage of that morning's attacks on the World Trade Center and the Pentagon.

The viewer figure may actually be higher. A Nielsen Media Research representative said the television ratings company tried to include all cable networks that were simulcasting other networks' news coverage in prime time, but as of late yesterday was not certain it had accounted for all of them.

At any rate, 80 million is approximately the same number of people who watched this past January's Super Bowl.

Exactly how many people were watching television in the hours immediately following the morning attacks is still a mystery. Part of the problem in obtaining such numbers is that Nielsen does not measure television-viewing in office buildings, which is where millions of Americans were when the first hijacked plane slammed into the skyscraper at 8:45 a.m.

The most watched broadcast last week was NBC's Tuesday night coverage of the terrorist hijackings, averaging more than 22 million viewers from 8 to 11. ABC News averaged 17.6 million, CBS News 14.4 million and Fox, which was simulcasting Fox News Channel, averaged 5.6 million.

Those large audiences will not go into the record books, however, because the broadcast networks' news coverage Tuesday through Friday was aired "sustaining," that is, without advertising. And Nielsen does not include noncommercial programming on the broadcast networks in its rankings.

With more than half of the major networks' prime-time programming airing without advertising, last week's ratings numbers "became sort of meaningless," a Nielsen rep told The TV Column. "It's so out of the norm that it just doesn't make much sense to look at it."

In fact, Nielsen decided yesterday to expunge the week of Sept. 10-16 from its prime-time ratings records because the Big Four networks scrapped four evenings' worth of entertainment programming. Between Tuesday and Saturday, ABC, CBS, NBC and Fox clocked the longest continuous stream of coverage for a single news story in TV history.

Nielsen provided the networks with information about the audience sizes for individual programs, but the week, which was to have been the 50th of the 2000-01 TV season, will be wiped from the books. Figures generated on programs running with ads last week are the official final national numbers.

Numbers for Tuesday-Friday news coverage are "fast national" estimates, which are based on station averages across the country. However, Nielsen will not put out fast nationals for CBS and CNN news coverage that was simulcast Tuesday on UPN and WB, respectively -- because UPN and WB do not pay to get "fast national" numbers.

CNN, which had averaged just 808,000 prime-time viewers on Monday, soared to 7.7 million on Tuesday. Fox News Channel, averaging 795,000 viewers Monday, leapt to 4.4 million Tuesday. MSNBC, after averaging an audience of 338,000 on Monday, jumped to 2.4 million Tuesday.

CNN's parent company, Turner Broadcasting System, put out a ranking of all cable programs last week, in prime time and out, showing that the 39 highest-rated cable programs were all on CNN. But how CNN is defining a "program" is unclear. On Tuesday night, for instance, CNN had eight different, individually rated programs on the list; three of them aired between 8:30 p.m. and 8:38 p.m.

But all ratings sources contacted agreed that CNN had the week's top-ranked cable program in its coverage of President Bush's speech Tuesday night; during that six-minute address, CNN drew 10.6 million viewers.

But those are nowhere near the numbers of people who turned to the broadcast networks for news of the attacks. Not far behind NBC's Tuesday prime-time newscast, ABC's season debut of "Monday Night Football" averaged 19.8 million viewers, making it the most watched program of the 10 hours of prime-time programming that carried advertising last week on the bigger networks.

On Wednesday night, the audience for the broadcast and cable networks' news coverage fell to about 55 million and by Friday was down to 40 million.

Broadcasters returned to more regular schedules over the weekend, including a bunch of feel-good movies that they assumed would be welcomed by viewers looking for escape after hour upon hour of news. They were wrong. On Saturday and Sunday, news specials won their time slots.

Sunday's second episode of HBO's much-hyped World War II miniseries, "Band of Brothers," logged about 7.3 million viewers, a loss of 27 percent compared with its premiere a week before. However, HBO had suspended all promotions for last Sunday's telecast after the attacks, fearing viewers would find the graphic promos tasteless under the circumstances.

Staff writer John Maynard contributed to this report.