The Crab Nebula in X-rays as imaged by the Chandra X-ray Observatory. The Crab Nebula has a pulsar at its heart, and was the fastest known pulsar, with a period of 33 milliseconds, until even faster pulsars were discovered with periods of just a few milliseconds.
Ginga was designed with two major science objectives in mind:
Study time variabilities from milliseconds to years for all types of X-ray sources: The light we see from objects in space can change over time; some objects take years or longer to change very much, while others change very quickly. For example, some pulsars spin rapidly, completing a complete revolution in just a few milliseconds (equivalently, they spin hundreds of times each second!). In order to see such changes, astronomers need data with a high time-resolution, meaning that they can tell exactly when a photon entered the detector compared to other photons.
Study the spectra of sources: Spectra tell astronomers how much light is emitted at each different wavelength. The About Spectroscopy pages tell more about spectra and what astronomers can learn from them.
Ginga performed approximately 1000 observations of about 350 different objects. The observing program included all known classes of X-ray sources.
