American Satellite Co., the Rockville communications satellite firm, has acquired Western Union Corp.'s government systems division for $155 million in cash.

The acquisition of the Tysons Corner-based division, which had sales last year of $120 million, will double American Satellite's revenue to about $240 million, according to American Satellite President George Roberts.

Although managed by American Satellite, the acquisition was financed by American Satellite's parent company, Continental Telecom Inc., and represents the Atlanta-based communications firm's latest foray into the federal data-communications market. Contel became the sole owner of American Satellite in October when it purchased 50 percent from Fairchild Industries Inc., its joint partner in the venture.

The new purchase "is a natural fit with the business American Satellite is already in -- providing services to a strong customer base of government agencies and large businesses," said John N. Lemasters, Contel's president and chief executive officer.

The government systems division, which employs 450 people, including 300 in the Washington area, provides private communications and data-processing services to agencies of the federal government. One of its most important contracts is to provide transmission services for the Defense Department's data communications network.

The acquisition, which is still subject to regulatory approval, "significantly increases our revenues, expands our customer base and brings a wealth of technical expertise to the company," Roberts said.

He added that AmSat will operate the government systems division as an independent subsidiary, using current management. AmSat, he said, will fill the same role that Western Union filled previously -- providing data transmission services and certain administrative functions.

Western Union's sale of the division is part of a major restructuring by the New Jersey-based company designed to infuse the firm with cash and reduce its debt. "Our strategy is to focus on Western Union's commercial and consumer telecommunications businesses," said Robert E. Leventhal, Western Union's chairman and chief executive officer.

The $155 million purchase price covers the acquisition of the division's assets and business and one year of transmission and maintenance services from Western Union, according to a statement. In addition, American Satellite has agreed to purchase similar services from Western Union for at least one more year.

The Howard Hughes Medical Institute, the medical research organization that last year became the beneficiary of a $5.2 billion windfall from the sale of Hughes Aircraft Co. to General Motors Corp., last week announced it will relocate its administrative headquarters to larger offices in Bethesda.

HHMI's 20-person administrative staff will grow to more than 150 over the next three years, according to Henry Kuss, vice president for administration.

The Hughes Institute, the largest private medical research organization in the world, will relocate its administrative staff to the top two floors of Two Rockledge Center, 6701 Rockledge Dr. in Bethesda, from its current offices at 7984 Old Georgetown Rd. Spaulding & Slye represented both the tenant and the landlord in the lease.

HHMI will begin moving into the new 50,885-square-foot facility before the end of March, Kuss said. The move isn't expected to be completed until the end of the year.

Kuss said the 130 new jobs will fall into four areas: investment analysts and brokers who will be responsible for making the organization's investments; accountants and financial specialists who will oversee spending and financial audits; scientists and scientific administrators who will establish research programs and ensure their quality, and an enlarged administrative staff.

T. Rowe Price Associates Inc., the large Baltimore investment company, has formed a Los Angeles-based subsidiary to acquire and manage real estate for investors.

T. Rowe Price, which manages nearly $20 billion, primarily in pension-fund accounts and 17 mutual funds, said creation of the new firm was based on an enthusiastic reaction to a real estate limited partnership introduced in 1984. More than $90 million was invested in the partnership, Realty Income Fund I, during its five-month offering period, it said.

"We consider real estate an important part of a diversified investment program, and, therefore, a logical addition to our existing investment management services," said James S. Riepe, president of T. Rowe Price Investment Services Inc.

The new company, T. Rowe Price Realty Advisers, will be headed by Reid G. Samuelson, formerly president of Coldwell Banker Capital Management Services, and will be staffed with a team of Samuelson's associates from Coldwell Banker, T. Rowe Price said.

Initially, Realty Advisers will supervise the completion of property acquisition for RIF I and prepare for RIF II, which is expected to be available in March, the company said. Realty Advisers also may manage institutional accounts.

Interactive Television Co. in Arlington has won a $1.5 million contract to produce 39 videodisc maps and indexing software for the Defense Mapping Agency. The contract is for 18 months. In addition, ITC has received $350,000 in contracts from several government agencies for Tempest microcomputer-controlled videodisc map display systems.

American Management Systems Inc., an Arlington company that designs computer systems to tackle large organizational management problems, has signed contracts totaling $1.9 million to supply its college and university financial management system to the universities of Cincinnati and Montana and the Archdiocese of St. Louis, among other organizations.

Cogenic Energy Systems Inc. in Ashland, Va., has signed contracts to make and install modular power "cogeneration" units at nursing homes in California, Arizona and New York, United Press International reported.

The contracts have a total value of about $1 million. The equipment will be made at the company's Ashland manufacturing plant, which employs about 40 people.

Cogeneration is the production of power for two or more purposes from one piece of equipment.