Along the Ratings Rialto . . . the two-hour Texas 150 celebration special on ABC Monday night earned an 11.7 rating and a 19 percent audience share in the national Nielsens . . .

That compared with a 12.4/20 for the rerun of "An Early Frost" on NBC and an average of 18.2/29 for the CBS lineup between 9 and 11 p.m. . . .

Locally, the one-hour Channel 7 special, "Adam and Eve Today," averaged a 6.6/12 Nielsen count between 8 and 9 while Part I of the syndicated mini-series "Strong Medicine" on Channel 20 averaged just 2.1/3 between 8 and 10 p.m. . . .

"Texas 150" did an 8.7/14 on WJLA, "Early Frost" did a 9.0/15 on WRC, and the CBS lineup averaged a strong 22.1/37 on WDVM . . .

Through late yesterday afternoon, CBS News seemed to have a slight jump on the competition regarding that nuclear plant disaster in the Soviet Union . . .

Monday, anchor Dan Rather was on the air with a bulletin at 2:30 p.m. Yesterday, Douglas Edwards had a bulletin at 12:39 p.m. and Dan was on again at 2:49 . . .

ABC News cut-ins on the story were confined to a single Peter Jennings appearance at 2:15 p.m. yesterday. NBC News devoted a half-hour yesterday morning to the moving ceremony for the Challenger astronauts but limited its nuclear coverage over the two days to a single cut-in by Tom Brokaw yesterday at 1:15 p.m. . . .

We're detecting, in sum, a little aggressiveness from CBS News lately (Dan was all over the Libya attack starting that first Monday) . . .

And why not? Just last week, "CBS Evening News With Dan Rather" finished first with a 12.0 Nielsen rating and a 23 share (an average of 10.3 million homes nightly), compared with a 11.7/23 (or 10 million homes) for "NBC Nightly News With Tom Brokaw" and an 11.1/21 for "ABC World News Tonight With Peter Jennings" (9.5 million) . . .

That's a spread of less than one rating point . . .

Captain Airwaves really likes the new Roy Rogers restaurant commercials featuring either "the official Spokeschicken" (who urges people to eat hamburgers) or "the official Spokescow" (who tries to sell viewers on chicken) . . .

The two 30-second spots, the first of nine in all, are airing in the major markets between here and Hartford, Conn., where most Roy Rogers restaurants are located . . .

Mark Goldstein, executive vice president and corporate creative director for Earle Palmer Brown, the Bethesda-based agency that is turning out the ads for the Marriott-owned chain, said yesterday, "The feedback has been fabulous. People are already taking sides, rooting for either the Spokescow or the Spokeschicken" (as a journalist, Airwaves must remain neutral, of course) . . .

The National Geographic Society and WQED in Pittsburgh, coproducers of the 1981 National Geographic Special "The Sharks," announced yesterday that Alan Landsburg Productions Inc. of Los Angeles has admitted the unauthorized use of "a dramatic segment" from that special and has settled for an undisclosed amount of cash . . .

In 1983, according to the Geographic, without permission from the producers, Landsburg Productions made a copy of "The Sharks" and used 90 seconds of it in a commercial TV special, "Sharks Don't Die: The Making of Jaws 3-D" . . .

The coproducers filed suit for copyright infringement in U.S. District Court for California's Central District. The settlement was reached on the eve of trial . . .

On the other hand, Home Team Sports is registering no more than a grumble over a half-time incident Sunday on CBS during the Bullets-76ers game . . .

CBS Sports announced the "world premiere of 'Block the Ball,' a Manute Bol Video" and proceeded to show 60 seconds from a five-minute Bol video produced for and seen on HTS cable during Game 4 of the series on Thursday . . .

CBS had called HTS on Friday to ask if they could use it . . . but HTS at least expected "a courtesy credit" on Sunday, according to HTS spokesman Mike Ortman . . .

Airwaves was unable to reach CBS Sports for comment yesterday . . . It's Sweeps Time!

Tonight at 5, the 20 finalists will be on hand for WRC's "Live at Five" newscast when the winner of the cruise with the "Today" show gang in mid-May is picked . . .

WRC and radio station WAVA each supply 10 contestants . . .

Tomorrow, "Live at Five" begins its 20-day tour of the area by broadcasting live from The Plains, Va. . . .

Also today, Channel 9 will launch a three-day report by consumer reporter Ellen Kingsley as she tests the fish market for "ingredients not on the label," while tomorrow, Channel 7 medical reporter Marilyn Mitzel will start a four-part series on premenstrual syndrome which will air in the 5 and 11 p.m. news shows . . .

The reason for all this activity? The start of the May ratings sweeps (actually Nine began reports on air travel safety by Kent Jarrell on Monday which run through tonight as a kickoff) . . .

Overlooked in that announcement that Lee Rich moves from Lorimar to become chairman and chief executive officer of United Artists Corp. is the fact that former ABC Broadcast Group president Tony Thomopoulos has been promoted from vice president to president and chief operating officer of UA Corp. . . .

On C-SPAN this morning at 10: the Senate Foreign Relations Committee hearings on U.S. embassy security . . .

Incidentally, C-SPAN will air the May 21 House hearings on satellite dishes on May 23, from 2 to 6 p.m. . . .

I Can't Stand It! Peter Davison, the latest (fifth) "Dr. Who," will be in town Friday, May 9, to mark the start of a 180-city tour of the "Dr. Who traveling exhibition" . . .

The (dare we call it a Whomobile?) Whomobile is a 48-foot van crammed with Whonots and Whatnots from the long-running BBC series, now seen on Channel 26 here . . .

The Whomobile will be parked at the west end of the Museum of American History for three days starting May 9 and will be open from 10 a.m. until 9 p.m. daily. For free . . .

Davison will show up at a ceremony at 11 that same morning . . . all this is in aid of a June 15 start on Channel 26 of a new series of 19 hour-and-a-half episodes of "Dr. Who" . . . TV Ratingzzzz

A couple of new, above-average but basically solemn movies helped CBS (with "Resting Place") and ABC (with "Alex: The Life of a Child") finish ahead of season-winner NBC last week . . .

CBS also introduced two series, "Bridges to Cross" (18th) and "Leo & Liz in Beverly Hills" (30th), which managed to stay out of trouble . . .

Meanwhile, total audiences for the three networks dropped more than 12 percent from the previous week as reruns dominated the schedule . . .

For the week ending April 27, CBS was first with a 14.3 rating and a 24 share, followed by ABC at 12.9/22 and NBC at 12.3/21 . . .

Skipping down the list of unlikely candidates for the Primetime Pantheon, NBC's "Missing III: Have You Seen This Person?" tied for 46th and NBC's "The Last Precinct" tied for 48th . . .

The NBC White Paper, "The Japan They Don't Talk About," had a 9.6 rating to finish in a six-way tie for 50th that also included NBC's "American Film Institute Salute to Billy Wilder," ABC's Wide World of Sports 25th anniversary special and CBS' "Tough Cookies" . . .

Rounding out the Final And If You Can't Get Their Attention During the Reruns Probably Fatal Five Plus Four last week were, in order, ABC's "Mr. Sunshine" in 56th, followed by CBS' "Morningstar/Eveningstar"; NBC's "TV Bloopers"; NBC's "Third Annual TV Academy Hall of Fame"; and the NBC pilot "Handsome Harry's" . . .

Continuing with the FAIYCGTADTRPFFPF, ABC's "Joe Bash" was 61st, followed by NBC's "Fathers & Sons"; NBC's "Punky Brewster"; and ABC's fallen "Fall Guy" just lying there, dead as today's -- let's make that yesterday's -- TV Column, in 64th and last place . . .