Аннотация:A harmonic development of the Earth tide generating potential (TGP) by an improved spectral method over two thousands years, 1000–3000, is done. The expansion is directly made to Poisson series where both amplitudes and frequencies of the series’ terms are high-degree polynomials of time as opposed to classical Fourier analysis where the terms’ amplitudes and frequencies are constants.The final development of the TGP, named KSM03, includes some 27,000 terms of amplitudes down to the level of 1*10−8 m^2/s^2. The respective accuracy in calculation of gravity tides at a midlatitude station is 0.025/0.39 nGal (the r.m.s./maximum error) when comparing with a benchmark gravity tide series numerically computed with use of the most accurate ephemeris DE-405 at every hour within 1600–2200. It exceeds the accuracy of any previously made harmonic development of the TGP in time domain by a factor of at least 3.