Father Gilbert Hartke, professor emeritus of drama at Catholic University, who underwent a colon operation Aug. 8, received a note from President Reagan that, Hartke said, "made some witty observation like 'I wonder if you think this thing is catching.' It was a very lovely note." Reagan was referring to the fact that Hartke had a colon operation similar to the president's. But Hartke noted, "Not being snobby, but mine was at the top and his was on the bottom." Hartke, 78, who says he is recovering 1,000 percent, was released from Providence Hospital last Saturday to recuperate at home . . .

American photographer Peter Beard pleaded guilty yesterday to violating Kenya's immigration laws by being in the country without a visa. A judge fined him the equivalent of $294 . . .

Film director Peter Bogdanovich said yesterday he hopes he and Playboy magazine publisher Hugh Hefner can end their feud now that Louise Hoogstraten, sister of Dorothy Stratten, the slain Playmate of the Year, has dropped a $5 million suit against Hefner . . .

Two Chinese organizations filed a $100 million class action lawsuit yesterday against director Michael Cimino, claiming his movie "Year of the Dragon" portrays the Chinese community as rampant with organized crime. The Los Angeles Superior Court suit, filed by the Federation of Chinese Organizations of America and the Chinese Consolidated Benevolent Association, seeks a court order prohibiting the distribution of the film . . .

South African heart surgeon Dr. Christiaan Barnard has accepted a full-time staff position at Baptist Medical Center in Oklahoma City, a hospital spokesman said yesterday.

Barnard, who performed the world's first heart transplant in 1967, will start next year and work a minimum of eight months a year for five years, the spokesman said.