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FOS - Faint Object Spectrograph

This picture of the Faint Object Spectrograph (FOS) was taken after the instrument was brought back to the Earth again.

The Faint Object Spectrograph (FOS) was exchanged with STIS during the Second Servicing Mission and brought back to Earth. A spectrograph spreads out the light gathered by a telescope so that it can be analysed to determine such properties of celestial objects as chemical composition and abundances, temperature, radial velocity, rotational velocity, and magnetic fields.

FOS examined fainter objects than the GHRS, and could study these objects across a much wider spectral range. The FOS had two modes of operation - low resolution and high resolution. In low resolution mode it reached 26th magnitude in one hour with a resolving power of 250. At high resolution, the FOS reached only 22nd magnitude in an hour, but the resolving power was increased to 0.9 Ångström at 1200 Ångström.

FOS Facts

Instrument type

Spectrograph

Resolution

Low resolution:	5 Å at 1200 Ångström
High resolution:	0.9 Å at 1200 Ångström

Wavelength Range

1150 to 8500 Ångströms

	WFPC1 - Wide Field Planetary Camera 1
	GHRS - Goddard High Resolution Spectrograph

Last Update: 04 Jun 2009

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FOS - Faint Object Spectrograph

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