Geocoronal hydrogen studies using Fabry–Perot interferometers, part 1: Instrumentation, observations, and analysis

Ground-based Fabry–Perot observations of the solar excited Balmer α emission line of neutral atomic hydrogen have become one of the primary means of studying the distribution and behavior of hydrogen in the thermosphere+exosphere. This first of two companion papers on “Geocoronal Hydrogen Studies Using Fabry–Perot Interferometers”, will outline the technique of Fabry–Perot spectroscopy as applied to geocoronal hydrogen. Representative high spectral resolution data sets will be discussed which will serve to highlight advances in instrumentation and in the interpretation of geocoronal Balmer α intensity and line profile observations. A second companion paper will address long-term observations of the Balmer α emission.