EC (Henry Norris Russell’s student)

EC, or E.C. (Henry Norris Russell’s student), likely refers to a scientific concept or notation related to the work of astronomer E.C. (or a similar initials, depending on the context). If you are referring to a specific figure, such as E.C. or an abbreviation for a concept in astronomy or physics, please provide more details. Alternatively, if you mean a scientific term or acronym associated with Russell’s work, please clarify so I can give an accurate explanation. Generally, Russell was known for stellar classification and astrophysics, so EC might relate to an astronomical classification or measurement.