Assessing polynomial approximation for AT

The time based on the rotation of the earth around its own axis is known as Universal Time [UT], it is not a uniform time scale. Another time scale based on the revolution of earth in its orbit around the sun, called Terrestrial time [TT]. The difference between TT and UT is known as delta T [Delta T]. Delta T varies slowly but rather irregularly. The exact value of Delta T cannot be predicted because the rate at which earth's rotation is slowing down is not known. Therefore, delta T can only be deduced form observations. The knowledge of the exact value of Delta T is essential for predicting the correct time of astronomical event or to confirm the time of Historical events. If Delta T is not considered the result may contain an error of several seconds. The value of Delta T can be found in almanacs, where it is given in seconds of times at January 1 for each year but for some calculation of the astronomical events we require its values at any date of the year. In such cases an approximate formula can make the life simple. This paper discuss a polynomial approximation to Delta T for the range of 1620 to 2000 AD published by Jean Meeus and Larry Simons and gives a modified version of this approximation which is much more accurate

Almanaque histórico: Oswaldo Cruz: o médico do Brasil / History almanac: Oswaldo Cruz: the doctor of Brazil

O Projeto Memória - uma parceria entre a Fundação Banco do Brasil e a Odebrecht - vem, desde 1997, resgatando, difundindo e preservando a história de fatos e personalidades que, nas mais diversas áreas, tenham contribuído para formar a identidade cultural do país. Em 2003, o Projeto Memória conta com a colaboração fundamental da Fundação Oswaldo Cruz (FIOCRUZ), entidade centenária que o sanitarista pôs de pé, e à qual dedicou seus mais generosos esforços.