Vector Magnetic Fields and Electric Currents from the Imaging Vector Magnetograph

First, we describe a general procedure to produce high quality vector magnetograms using the Imaging Vector Magnetograph (IVM) at Mees Solar Observatory. Two IVM effects are newly discussed and taken into account: (1) the central wavelength of the Fabry-Pérot is found to drift with time as a result of undiagnosed thermal or mechanical instabilities in the instrument; (2) the Stokes V -sign convention built into the IVM is found to be opposite to the conventional definition used in the study of radiative transfer of polarized radiation. At the spatial resolution 2′′ × 2′′, the Stokes Q,U, V uncertainty reaches ∼ 1 × 10−3 5 × 10−4 in time-averaged data over 1-hour in the quiet Sun. When vector magnetic fields are inferred from the time-averaged Stokes spectral images of FeI 6302.5 Å, the resulting uncertainties are on the order of 10 G for the longitudinal fields (B‖), 40 G for the transverse field strength (B⊥) and ∼ 9◦ for the magnetic azimuth (φ). The magnetic field inversion used in this work is the “Triplet” code, ar X iv :0 81 1. 00 54 v1 [ as tr oph ] 1 N ov 2 00 8