President Shimon Peres will celebrate his 86th birthday on Sunday. Prior to his assumption of the presidency, biographical data gave August 16 as his date of birth. The change occurred after he decided that from a personal standpoint, he would celebrate his birthday according to the Hebrew calendar date of Av 20, which in 1923, the year of his birth, coincided with August 2. However, there are many people who still consider Peres to have been born on August 16, among them composer Kobi Oshrat who has set several of Peres's poems to music, and with the voluntary input of several entertainers has produced a CD which will be launched at a birthday tribute to Peres on August 16 at the Wohl Amphitheater in Tel Aviv. Oshrat, a former cultural consul in Los Angeles, and a long time associate of the president's, has put together a 12-song album which will be accompanied by a tribute concert during which Peres will be made an honorary fellow of EMI, the Hebrew acronym for the Union of Israeli Artists. Among the performers on the CD album and/or at the concert are Matti Caspi, Izhar Cohen, Ninet Tayeb, Ofira Gluska, Arik Sinai, Miri Mesika, Arkadi Duchin, Mazi Cohen and Shlomo Gronich. The resignation on Thursday by Fiji's president, Ratu Josefa Iloilovatu Uluivuda, who served in the post for nine years, may now allow Peres to become the world's oldest ever head of state. Ratu Josefa is 88. Konrad Adenauer, the long serving chancellor of Germany, was 87 and three-quarters when he completed 14 years in office. In comparison, former South African president Nelson Mandela, who celebrated his 91st birthday on July 18, was a spring chicken when he left office 10 years ago at age 81. If Peres completes his seven-year term, he will indeed hold the record for the world's oldest ever head of state. However, the record for the world's longest serving heads of state belongs jointly to two monarchs. Thailand's King Bhumibol Adulyadej has been on the throne for 63 years and Britain's Queen Victoria was on the throne for 63. The present queen, Elizabeth II, has been on the throne for 57 years.