Basic principle of Multi-Object Spectroscopy rearranged

A multi-object spectrometer is a type of optical spectrometer capable of simultaneously acquiring the spectra of multiple separate objects in its field of view. It is used in

astronomical spectroscopy Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and othe ...

and is related to long-slit spectroscopy. This technique became available in the 1980s.

Description

The term multi-object spectrograph is commonly used for spectrographs using a bundle of

fibers Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

to image part of the field. The entrance of the fibers is at the focal plane of the imaging instrument. The bundle is then reshaped; the individual fibers are aligned at the entrance slit of a spectrometer, dispersing the light on a detector. This technique is closely related to integral field spectrography (IFS), more specifically to fiber-IFS. It is a form of

snapshot hyperspectral imaging Snapshot hyperspectral imaging is a method for capturing hyperspectral images during a single integration time of a detector array. No scanning is involved with this method and the lack of moving parts means that motion artifacts should be avoide ...

, itself a part of imaging spectroscopy.

Apertures

Typically, the apertures of multi-object spectrographs can be modified to fit the needs of the given observation. For example, the MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration ) instrument on the W. M. Keck Observatory contains the Configurable Slit Unit (CSU) allowing arbitrary positioning of up to forty-six 18 cm slits by moving opposable bars. Some fiber-fed spectroscopes, such as the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) can move the fibers to desired position. The LAMOST moves its 4000 fibers separately within designated areas for the requirements of a measurement, and can correct positioning errors in real time. The

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

uses a fixed Micro-Shutter Assembly (MSA), an array of nearly 250000 5.1 mm by 11.7 mm shutters that can independently be opened or closed to change the location of the open slits on the device.

Uses in telescopes

Ground-based instruments

Instruments with multi-object spectrometry capabilities are available on most 8-10 meter-class ground-based observatories. For example, the Large Binocular Telescope, W. M. Keck Observatory, Gran Telescopio Canarias, Gemini Observatory, New Technology Telescope, William Herschel Telescope, UK Schmidt Telescope and

LAMOST The Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), also known as the Guo Shoujing Telescope (Chinese: 郭守敬望远镜) after the 13th-century Chinese astronomer, is a meridian reflecting Schmidt telescope, located in Xing ...

include such system. Four instruments in the Very Large Telescope, including the KMOS (K-band multi-object spectrograph) and the

VIMOS The Visible Multi-Object Spectrograph (VIMOS) is a wide field imager and a multi-object spectrograph installed at the European Southern Observatory's Very Large Telescope (VLT), in Chile. The instrument used for deep astronomical surveys deliver ...

(Visible Multi Object Spectrograph) instruments, have multi-object spectroscopic capabilities.

Space-based instruments

The Hubble Space Telescope has been operating the

NICMOS The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a scientific instrument for infrared astronomy, installed on the Hubble Space Telescope (HST), operating from 1997 to 1999, and from 2002 to 2008. Images produced by NICMOS contain ...

(Near Infrared Camera and Multi-Object Spectrometer) from 1997 to 1999 and from 2002 to 2008. The

's NIRSpec (Near-Infrared Spectrograph) instrument is a multi-object spectrometer.

References

{{reflist Observational astronomy Astronomical spectroscopy