IBIS
The Interferometric BIdimensional Spectropolarimeter

Astronomy Picture of the Day, Nov 2, 2010: IBIS mosaic of AR NOAA 11092, imaged in the core of chromospheric Ca II 854.2 nm (left) and H-alpha 656.3 nm (right). Field of view is about 4' x 4', from 3x3 tiles of 95"x95" each, with a pixel scale of 0.095 arcsec/pixel.

The Interferometric BIdimensional Spectropolarimeter - IBIS - is a high cadence, dual interferometer imaging spectro-polarimeter, installed at the Dunn Solar Telescope of the US National Solar Observatory in New Mexico. By means of precise piezo-electric tuning, IBIS can rapidly and reliably scan selected spectral lines within the 550-860 nm range. Thanks to its optical characteristics and to the efficient DST AO system, IBIS produces high-fidelity imaging spectroscopy and polarimetry of the solar photosphere and chromosphere.   Its large field-of-view, high spatial and spectral resolution, and stable and repeatable performances, have made IBIS a very successful and versatile instrument, suited for a variety of investigations on the solar atmosphere.

The movie illustrates the principle of imaging spectroscopy: as the (very narrow) passband of IBIS is stepped through the CaII 854.2 line, the images sample different parts of the solar atmosphere, from the mid photosphere (e.g. reverse granulation) to the mid chromosphere (fibrils etc). See also Cauzzi et al. 2008

IBIS has been built by the INAF-Arcetri Astrophysical Observatory, with the support of the Dept. of Physics and Astronomy of the University of Florence, and the Dept. of Physics of the University of Rome - Tor Vergata. It is currently operated and supported by INAF in collaboration with the US National Solar Observatory. IBIS has been a DST facility instrument since 2005. If you are interested in using IBIS, please contact Gianna Cauzzi for further information.