Poljancic, I; Brajsa, R; Hrzina, D; Wohl, H; Hanslmeier, A; Potzi, W; Baranyi, T; Ozguc, A; Singh, J; Ruzdjak, V
(Hvar Observatory, 2011)
Measured positions of sunspot groups that differ in format, precision and observing procedure are collected from various data sets: GPR (Greenwich Photoheliographic Results), SOON/USAF/NOAA (Solar Optical Observing ...