  We analyze spectropolarimetric observations of the chromospheric Ca II 8542 A
line taken by the Interferometric Bidimensional Spectrometer (IBIS) at the Dunn
Solar Telescope. The data were observed on 2012 January 29 for the NOAA active
region 11408. Adopting the center-of-gravity (COG) approach we obtain the
line-of-sight (LOS) field strength for the chromospheric IBIS data of Ca II
8542 A line. The LOS strength of the magnetic field is determined in the target
active region inside a field of view 45 x 95 arcsec. The LOS field values were
found to be increase up to 800 G inside the umbral region and decrease
systematically toward the edges of a sunspot. Under the weak field
approximation (WFA), the horizontal, vertical magnetic field components and
azimuthal field vector are obtained.
