The body of knowledge obtained using methods based upon systematic observation is called science.

Here's why:

* Systematic observation: Science relies on careful and organized observation of the natural world, using tools and techniques to gather data.

* Methods: These observations are guided by specific methods and procedures that ensure accuracy and reproducibility.

* Body of knowledge: The accumulated data and insights from scientific observation form a comprehensive body of knowledge about the universe and its workings.

While there are different branches of science (like biology, physics, chemistry, etc.), they all share this fundamental approach of using systematic observation to build and expand knowledge.