One of the ways to explore gas in the Universe is using HI absorption observations. The new radio telescopes -ASKAP, MeerKAT and Apertif on the WSRT- offer exciting new possibilities for science using HI absorption. Coordinating the groups planning to exploit these data was one of the motives for a small but very lively workshop held at ASTRON 14th to the 16th of June 2017.
HI absorption observations are complementary to those tracing the HI gas in emission because they allow detecting gas much distant objects and to image the gas at very high spatial resolution, i.e. at parsec scales reachable by VLBI. Thus, HI absorption observations are ideal to study the gas e.g. in the surrounding active nuclei.
The workshop covered a number of important topics, from the status of the new (or upgraded) telescopes, and of the tools to exploit the upcoming surveys, to the science we want to do with the data and the complementarity of the various surveys. Its schedule included ample time for discussion and each session had presentations of participants and was followed by a discussion about open issues. A number of action points have been decided.
About forty astronomers from all over the world attended the workshop; a very lively community ready to start exploiting the data beginning to appear from all telescopes.
Organiser: Raffaella Morganti