First Observations from the Multi-Application Solar Telescope (MAST) Narrow-Band Imager

Abstract

The Multi-Application Solar Telescope is a 50 cm off-axis Gregorian telescope recently installed at the Udaipur Solar Observatory, India. In order to obtain near-simultaneous observations at photospheric and chromospheric heights, an imager optimized for two or more wavelengths is being integrated with the telescope. Two voltage-tuneable lithium-niobate Fabry–Perot etalons along with a set of interference blocking filters have been used for developing the imager. Both of the etalons are used in tandem for photospheric observations in Fe i 6173 A and chromospheric observation in H $\alpha$ 6563 A spectral lines, whereas only one of the etalons is used for the chromospheric Ca II line at 8542 A. The imager is also being used for spectropolarimetric observations. We discuss the characterization of the etalons at the above wavelengths, detail the integration of the imager with the telescope, and present a few sets of observations taken with the imager set-up.