Editing Reflecting telescope (section)

===Fibre-fed spectrographs===

For instruments requiring very high stability, or that are very large and cumbersome, it is desirable to mount the instrument on a rigid structure, rather than moving it with the telescope. Whilst transmission of the full field of view would require a standard coudé focus, spectroscopy typically involves the measurement of only a few discrete objects, such as stars or galaxies. It is therefore feasible to collect light from these objects with [[optical fiber]]s at the telescope, placing the instrument at an arbitrary distance from the telescope. Examples of fiber-fed spectrographs include the planet-hunting spectrographs [[High Accuracy Radial Velocity Planet Searcher|HARPS]]<ref name="HARPS description">{{cite web|url=https://www.eso.org/sci/facilities/lasilla/instruments/harps/inst/description.html|title=HARPS Instrument Description}}</ref> or [[ESPRESSO]].<ref name="ESPRESSO description">{{cite web|url=https://www.eso.org/sci/facilities/develop/instruments/espresso.html|title=ESPRESSO Instrument Description}}</ref>

Additionally, the flexibility of optical fibers allow light to be collected from any focal plane; for example, the HARPS spectrograph utilises the Cassegrain focus of the [[ESO 3.6 m Telescope]],<ref name="HARPS description" /> whilst the Prime Focus Spectrograph is connected to the prime focus of the [[Subaru Telescope|Subaru telescope]].<ref name="PFS Instrumentation">{{cite web|url=http://pfs.ipmu.jp/instrumentation.html|title=Subaru PFS Instrumentation}}</ref>