A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: I. Observations and Spectra

Abstract

We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic radio continuum sources, located at high (|b| > 15?) Galactic latitudes. The Declination coverage of the present survey is δ - 45?.With a mean rms optical depth of ? 0.003, this is the most sensitive Galactic HI 21- cm line absorption survey to date. To supplement the absorption data, we have extracted the HI 21-cm line emission profiles towards these 102 lines of sight from the Leiden Dwingeloo Survey of Galactic neutral hydrogen. We have carried out a Gaussian fitting analysis to identify the discrete absorption and emission components in these profiles. In this paper, we present the spectra and the components. A subsequent paper will discuss the interpretation of these results.