I have to say that is quite the phenomenal coat. I can see why it inspired you.
For your character, you could carry a bag that looks a bit roughed up full of gadgets, like your telescope, some vials of liquids (you could even make a belt or something with those exposed in it), bottles for holding materials for alchemy, and other little doodads. Wear some nice gloves with the outfit that might be a bit stained from the alchemy process. Maybe do some accessories based on astronomy, like a hat with star detailing or jewelry in that vein. I would also suggest some wire framed glasses, maybe the kinds that have various magnifying lenses on them.