A comparison of co-temporal magnetograms obtained with the Huairou magnetograph and the Spectro-Polarimeter on board Hinode
Zhang, Hongqi; Zhang, Mei; Li, Hui; Wang, Dong
China, United States
Abstract
We have compared a set of co-temporal magnetograms obtained with the Solar Magnetic Field Telescope (SMFT) of the Huairou Solar Observing Station (HSOS) and with the Spectro-Polarimeter of the Solar Optical Telescope (SP/SOT) on board Hinode to check the linear calibrations of SMFT vector magnetograms. The comparison shows that the currently used calibration coefficients of the SMFT have under-estimated the flux density and that a center-to-limb variation of the calibration coefficients was not taken into account by previous calibrations.