Question

how did astronomers use technology to identify characteristics of the crab nebula? technology that detects ultraviolet light found hydrogen in the nebula technology that detects radio waves identified a pulsar at the center of the nebula technology that detects microwaves revealed the behavior of electrons in the nebula technology that detects gamma rays measured the distance of the nebula from earth

Explanation:

Radio - wave detection is used to identify pulsars. Pulsars are often detected through radio - wave observations in nebulae like the Crab nebula.

Answer:

technology that detects radio waves identified a pulsar at the center of the nebula.