Far-Infrared 160 μm Survey by Balloon-Borne Telescopes

We have initiated a Japan-India collaborative project which surveys far-infrared emission from star-formation regions using balloon-borne telescopes. Two telescopes will be used for the observations. One is a 50-cm Japanese telescope equipped with a newly developed two-dimensional array of stressed Ge:Ga detectors. With this telescope, we will carry out a photometric survey of a 160-μm continuum with an angular resolution of 1.5' and a detection limit of 10 Jy. The other is an Indian 1-m telescope equipped with a Japanese Fabry-P&{acutee}rot spectrometer in its focal plane. With this telescope, we will survey a [C II] 158-μm spectrum line with a spatial resolution of 1.4' and a detection limit of 3 x 10^-5 ergs s^-1 cm^-2 sr^-1. Our objectives are to observe galactic star-formation regions as well as near-by external galaxies. By combining the results observed using these telescopes, we will attempt to reveal the energy balance between interstellar gas and dust. We will make our first observational flights of these telescopes this winter. During one observational flight, up to 100 square-degrees of the sky will be surveyed in a 160-μm continuum and 1 square-degree of the sky will be mapped in a 158-μm [C II] line emission.