Spherical Rectangular Equal-Area Grid (SREAG): Some features

Abstract

A new method Spherical Rectangular Equal-Area Grid (SREAG) was proposed in Malkin (2019) for splitting spherical surface into equal-area rectangular cells. In this work, some more detailed features of SREAG are presented. The maximum number of rings that can be achieved with SREAG for coding with 32-bit integer is $N_{ring}$=41068, which corresponds to the finest resolution of $\sim$16${}^{\prime \prime }$. Computational precision of the SREAG is tested. The worst level of precision is $7\cdot 10^{-12}$ for large $N_{ring}$. Simple expressions were derived to calculate the number of rings for the desired number of cells and for the required resolution.

Presented at the Journees 2019 "Astrometry, Earth rotation and Reference systems in the Gaia era", Paris, France, 7-9 Oct 2019. Supporting routines are included in the distribution