Cosmic Origins Spectrograph

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The Cosmic Origins Spectrograph (COS) is an instrument that is scheduled to be installed on the Hubble Space Telescope in September 2008 during STS-125. It is designed for ultraviolet (115-300 nm) spectroscopy of point sources with a resolving power of ~2,000 or 20,000. Its science goals include the study of the origins of large scale structure in the universe, the formation and evolution of galaxies, and the origin of stellar and planetary systems and the cold interstellar medium. The COS is being developed and built at the Astrophysics Research Lab in the Center for Astrophysics and Space Astronomy (CASA-ARL) at the University of Colorado at Boulder.

It will replace the bay currently occupied by the corrective COSTAR optical package, and is intended to operate in addition to the STIS spectrograph once it is repaired during the same mission. While STIS is able to operate on wider wavelengths, the COS is estimated to be some 10 times more sensitive in UV^[1].

Contents 1 Instrument components 2 See also 3 References 4 External links

[edit] Instrument components

COS has two channels, the Far Ultra-Violet (FUV) and Near Ultra-Violet (NUV).

Both channels use the same two apertures, a Primary Science Aperture (PSA) and a Bright Object Aperture (BOA). Both apertures consist of a 2.5 arc second diameter circle that is in the light path before the instrument's corrective optics. The difference between them is that the BOA includes a neutral density filter that attenuates the light by approximately two orders of magnitude (five magnitudes).

The FUV detector is a crossed delay line device optimized detecting light with wavelengths between 1150 and 1775 Ångströms (115 to 177.5 nm). It consists of two physically distinct segments separated by a small gap. Crossed delay line devices do not have physically distinct pixels, however, the electronics that quantize the location of each photon event effectively divide the surface up into 16384 by 1024 pixels. This channel has three gratings for low and medium resolution spectroscopy but no imaging mode.^[2]

The NUV detector is a Multi Anode Microchannel Array (MAMA) that can detect light with wavelengths between 1150 to 3200 Ångströms (115 to 320 nm). It is approximately square with 1024 by 1024 pixels. The NUV channel has four diffraction gratings for low and medium resolution spectroscopy. The grating selector also has a mirror providing an imaging mode but because of the limited field of view provided by the available apertures it is expected that this mode will be used for target acquisition wherein the position of the target is adjusted for optimal viewing.^[3]

[edit] See also

• Wide Field and Planetary Camera
• Wide Field and Planetary Camera 2
• Wide Field Camera 3
• Advanced Camera for Surveys
• Near Infrared Camera and Multi-Object Spectrometer
• Faint Object Camera

[edit] References

1. ^ HubbleSite - Servicing Mission 4
2. ^ [http://www.stsci.edu/hst/cos/documents/handbooks/current/cos_cover.html COS Instrument Handbook
3. ^ [http://www.stsci.edu/hst/cos/documents/handbooks/current/cos_cover.html COS Instrument Handbook

[edit] External links

• the COS Web site at the Space Telescope Science Institute (STScI)

v • d • e Hubble Space Telescope Associated Shuttle missions Launch STS-31 Servicing STS-61 · STS-82 · STS-103 · STS-109 Planned STS-125 Onboard instruments Current Advanced Camera for Surveys (ACS) · Corrective Optics Space Telescope Axial Replacement (COSTAR) · Fine Guidance Sensor (FGS) · Near Infrared Camera and Multi-Object Spectrometer (NICMOS) · Space Telescope Imaging Spectrograph (STIS) · Wide Field and Planetary Camera 2 (WFPC2) Planned Cosmic Origins Spectrograph (COS) · Wide Field Camera 3 (WFC3) Previous Faint Object Camera (FOC) · Faint Object Spectrograph (FOS) · Goddard High Resolution Spectrograph (GHRS/HRS) · High Speed Photometer (HSP) · Wide Field and Planetary Camera (WFPC) Italics indicate instruments that are currently failed and/or shut-down