Analysis of Vector Magnetic Fields in Solar Active Regions by Huairou, Mees and Mitaka Vector Magnetographs

We analyze the vector magnetograms in several well-developed active regions obtained at Huairou Solar Observing Station, National Astronomical Observatories of China, at Mees Solar Observatory, University of Hawaii, and at National Astronomical Observatory of Japan. It is found that there is a basic agreement on the transversal fields among these magnetographs. The observational error (mutual difference) for the transversal magnetic fields is estimated. In addition to comparison of transversal fields among different instruments, we used the morphological configurations of sunspot penumbrae in white-light and EUV 171 Å images obtained by the TRACE satellite as a reference of the orientation of transversal magnetic fields.