In the time interval 1749-1818 a great part of missing daily relative sunspot numbers was reconstructed by nonlinear two-step method of interpolation. In the first step directly interpolated were gaps not longer than five days. In the second step the data were sorted in the so called Bartels scheme, i.e. in rows of a length of 27 days
subsequently ranged in a matrix. In thís step the missing data of longer gaps were interpolated columnwise, i.e. missing value at any position was interpolated from the data at same column positions of preceeding and folloving rows. The interpolation was limited to sequences of no more than four missing data. The procedure enables interpolate long gaps and simultaneously respect the 27-day variation of solar activity. A part of missing data in the intervals, where the frequency of observations was very low and has not fullfilled the limitations of the interpolation method. was
not interpolated. Annual tables of daily data are given in Appendix A, monthly and annual means in Appendix B, and annual plots of daily data in Appendix C. The differences between monthly and annual means of the primary observations and of the data completed by interpolation fluctuate around zero. The amplitude of fluctuations
depends inversely on the frequency of observations. Most conspicuous are the deviations in the time interval 1776-1795, when the frequency of observations was wery low or almost zero. The dispersion of monthly differences σ is ±13.7 R and
of annual differences ±9.3 R. The results give insight on the reliability of relative sunspot numbers in the investigated time interval. and Součástí článku jsou 2 apendixy:
- Appendix A Daily relative sunspot numbers 1749-1818
(s. 7-42)
- Appendix B Monthly and annual means of relative sunspot numbers 1749-1818 (s. 43-66)