Like all telescopes used in scientific research, Hubble holds a range of filters. These highly specialized filters are pieces of physical hardware that allow a range of wavelengths (broadband filters) or very specific wavelengths (narrowband filters) of light to enter the telescope. This allows astronomers to look for specific features in the object. The data can tell us what elements are present, the temperature, and pressure of the object. The ability to probe extremely specific parts of the electromagnetic spectrum is very useful to astronomers. It helps them better understand the physical processes and environments of the objects they study.
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NASA's Goddard Space Flight Center, Greenbelt, MD