Narrow-band full Stokes polarimetry of small structures on the Sun with speckle methods

Aims. For the detection and the study of small-scale magnetic fields on the Sun, it is important to obtain observations with both high spatial resolution and high polarimetric sensitivity. Methods. A second narrow-band etalon and a full Stokes polarimeter, based on ferroelectric liquid crystals, were implemented in the two-dimensional Gottingen Fabry-Perot spectrometer/polarimeter at the Vacuum Tower Telescope, Observatorio del Teide/Tenerife. First observations with the Fe I 6173 angstrom line and their data analysis with speckle methods are described. Results. The new polarimeter yields magnetograms of a field of view of 31 '' x 52 '' with minimised seeing induced signals and without spurious signals as from the use of beam-splitting calcites. The achieved spatial and temporal resolution are 0 ''.30-0 ''.35 and 36s, respectively. With a detection limit for the field strength of 16G (equivalent to 3 sigma), a polarimetric sensitivity of 7-8 x 10(15) Mx is obtained. Examples of intensity maps, Dopplergrams, and magnetograms from quiet and active regions on the Sun are discussed. Some of the results on solar magnetism are on 1) a pore with small-scale structure where we find a region with very low temperature gradient, 2) polar faculae with strong magnetic field signals and weaker signals in other areas surrounding them, and 3) small-scale inter-network magnetic fields with area fillings in the resolution elements of the order of 0.15.