The GMRT archive atomic gas survey - I. Survey definition, methodology, and initial results from the pilot sample

Interferometric observations of H i in galaxies have played a pivotal role in studies of nearby galaxies. Compared to single-dish observations, they provide resolved distributions of gas in galaxies with unprecedented resolution. Several extensive H i surveys of nearby galaxies have been performed in the past; however, most of them consist of less than 100 galaxies due to individual efforts. On the other hand, the present-day archives of radio telescopes include data for at least several hundred galaxies. To utilize these data sets to their full potential, we construct a sample including all galaxies observed by the Giant Metrewave Radio Telescope in H i. This results in a total of 515 galaxies, the largest sample to date. We intend to analyse all the data uniformly and carry out different exciting science. As a pilot project, we analyse data from 11 galaxies and present the data products in this paper. We further investigate the neutral interstellar medium in these galaxies and extract cold and warm phases using a multi-Gaussian decomposition method. This pilot project assures the quality of the data, which will enable us to perform critical science investigations using the full sample.