Six weeks to the day after he announced his intention to move to Channel 4, Gordon Peterson yesterday signed a new contract with his old boss at Channel 9 and will return to his familiar co-anchor spot on the Eyewitness News Monday evening.

Terms of the new pact were not revealed but Ed Pfeiffer, vice president and general manager of WDVM, indicated yesterday it was a "long-term" contract that went considerably beyond the July 1980 expiration date of Peterson's original three-year pact with the stations.

Under that contract, Peterson was paid $155,000 a year, and as co-anchor for the highest-rated news show in the Washington market, his new pact with Channel 9 undoubtedly calls for at least that much.

Options under the old pact also called for a raise to $165,000 next year and $180,000 in 1981, in addition to a $100,000 insurance policy and an annual $2,500 clothing allowance.

Immediately after Peterson and Pfeiffer signed the new agreement yesterday afternoon, the two went to the nearby Channel 9 newsroom, where Peterson was greeted with an "ovation," according to Pfeiffer.

Peterson then joined some of his longtime friends at the station on a bus trip to Baltimore for last night's baseball game between the Orioles and the Boston Red Sox.

On Aug. 3, Peterson had stunned those same coworkers, as well as Pfeiffer, when he suddenly revealed that he had signed a contract with Channel 4 and would join Jim Vance as co-ahchor on the weeknight news there about Sept. 1.

Four days later, the Evening News Association, owners of Channel 9, took Peterson to court.

On Sept. 7, U. S. District Judge Barrington D. Parker ruled that Peterson had a valid contract with ENA and must either finish the current three-year pact in July 1980 or be barred from working at another TV station in the Washington market during that time.

Peterson, and lawyers for NBC, which owns Channel 4, had contended that his original three-year contract with Post-Newsweek Stations Inc., signed in 1977, had been assigned without his consent in June 1978 when PNS and ENA concluded a deal in which Channel 9 here was traded for an ENA-OWNED TV station in Detroit and the ownership changed hands.

In expectation of Peterson's arrival, Channel 4 management had notified co-anchor Jim Hartz on Aug. 3 that he was being returned to NBC News in New York for reassignment, at least through the remainder of his current contract, which expires at the end of this month.

Hartz, who is currently vacationing in the West, is expected to sit down with NBC News officials soon to either work out a new contract or negotiate severance pay.

Hartz has also reportedly received at least one lucrative offer to remain in TV outside of NBC News.

Pfeiffer, who had publicly expressed the hope Peterson would return, while privately acknowledging there could be morale problems for a while if he did, indicated no such qualms yesterday.

"We're absolutely delighted to have Gordon back. Gordon Peterson and Ed Pfeiffer have a new contract between us but I'm not going to discuss anything in the contract."

Referring to the resignation two days ago of news director Milt Weiss, Pfeiffer said Peterson "will have an input and play a major part in the selection" of Weiss' successor.

At the time he opted for Channel 4, Peterson had indicated that a main reason for making the move was a promise by WRC management that he could move into the decision-making side of the news operation there.

Pfeiffer said yesterday he "certainly hopes to get the best possible (news director) in the country" with Peterson's help and that the station will continue its "leadership in local news" with Peterson back.

Peterson on Monday will rejoin Maureen Bunyan on the 5 o'clock news and J. C. Hayward at 11 p.m. as co-anchor.

Officials at Channel 4 could not be reached late yesterday for comment on Peterson's return to WDVM. With Hartz's departure, Vance now co-anchors with Sue Simmons during the week, while newcomer Barbara Allen replaces Simmons as weekend anchor.