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 detailed guide here if you haven't used this tool before. Look for `fys5120-25v' 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! In fact, feel free to start using it right away for any questions about the background material ! [and yes, the latter is a subtle reminder to actually read the text... :)]