In this course we will use UiO Discourse (or AstroDiscourse) for communicating outside of lecture / group exercise hours. So please take a look at the here if you haven't used this tool before. Look for `fys4160-25v' once you have logged into the platform (with your standard student login).
In general, this kind of tool is really useful once one gets above a critical level of usage. So use it actively to ask and discuss any questions you may have!