Invisible sunspots and rate of solar magnetic flux emergence

摘要: Aims. We study the visibility of sunspots and its influence on observed values sunspot region parameters. Methods. use Virtual Observatory tools provided by AstroGrid to analyse a sample 6862 regions. By studying distributions locations where were first last solar disk, we derive function sunspots, rate magnetic flux emergence ratio between durations growth decay phases active Results. demonstrate that small has strong centre-to-limb variation, far larger than would be expected from geometrical (projection) effects. This results in large number young spots being invisible: 44% new regions emerging west Sun go undetected. For are detected, differences exist actual times emergence, apparent ones derived data. The duration phase been, up now, underestimated.