Tabulae Regiomontanae reductionum observationum astronomicarum ab anno 1750 usque ad annum 1850 computatae is a famous book written by Bessel and published in 1830. Friedrich Wilhelm Bessel (22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist(See Wiki https://en.wikipedia.org/wiki/Friedrich_Bessel).
I don't understand Latin, but I'm curious about what Bessel's book is about? This book was published in 1830, but the title of the book''ab anno 1750 usque ad annum 1850'' indicating that it was about events between 1750 and 1850. I would like to ask everyone about the content of Bessel's book and why he chose this title, infact published in 1830, but title ''ab anno 1750 usque ad annum 1850''.
The title of the book says ''ab anno 1750 usque ad annum 1850 computatae'', that is "computed". Bessel precomputed positions of stars for the near future: there was even an addendum from 1850 to 1860, according to this source. BTW, "reductionum" (plural genivite of "reductio") is not related to the English "reduction". It comes from Latin root "re-ducere", to bring back. In this context, it means that the anomalies in the calculation of the positions were written down.
As for the entitling to Regiomontanus, he published the Ephemerides, where he computed the planets' motions for the following 32 years. I suppose that "Tabulae Regiomontanae" were called so in his honor.