KMOS

Introduction
Specifications
Instrument Description
Further Information

INTRODUCTION

KMOS is a multi-object near-infrared integral field spectrograph being built as one of the second-generation instruments for the ESO VLT. The design is being undertaken by a consortium including the University of Durham, the Astronomical Technology Centre (ATC), the University of Oxford, the Universitätssternwarte München (USM) and the Max-Planck Institut für extraterrestrische Physik (MPE) working in collaboration with ESO who will provide the detectors and control systems. The science team also includes the University of Bristol. The Principal Investigator is Prof. Ray Sharples (Durham) and the deputy-PI is Prof. Ralph Bender (USM/MPE) . The primary science drivers for KMOS are the study of the intermediate and high-z slices of our Universe. The total budget of the project is €7.5M + 165 staff-years of effort and the major milestones are:

Milestone	Date
Preliminary Design Review	April 2006
Final Design Review	April 2007
Prliminary Acceptance Europe	March 2010
Preliminary Acceptance Chile	Sept 2010

BASELINE SPECIFICATIONS

The top level specifications for KMOS are:

Wavelength coverage 0.8-2.5 microns
Number of IFUs: 24
Instrument throughput: Z=15%, J=20%, H=30%, K=30%
Sensitivity (5sigma, 8hrs): Z=21.0, J=21.2, H=21.0, K=19.2
Integral Field Unit (IFU) type: image slicer
Patrol field: 7.2 arcmin diameter
IFU spatial sampling: 0.20 arcsec
IFU field size: 2.8x2.8 arcsec (14x14 spatial pixels)
Spectral resolution: R~3500
Number of spectrographs: 3

DESCRIPTION OF THE INSTRUMENT

KMOS is a cryogenically cooled multi-object, near-infrared spectrograph mounted in a single cryostat at the Nasmyth focus of one of the 8.2m VLT Unit Telescopes. Within the circular patrol field of view, individual objects can be selected with a cryo-mechanical pickoff arm which feeds the light via a constant optical path length to the IFUs. This mechanism allows flexible and efficient re-configuration of the IFUs. The IFUs dissect the field into individual spatial elements, which are then re-arranged to form part of the spectrograph entrance slit. The spectrographs are required to achieve a resolution of R~3500 to allow the use of OH avoidance techniques to improve the signal-to-noise in the J,H bands. The instrument naturally lends itself to a modular approach where a fixed number of arms and IFUs (8) are fed into a single ‘unit spectrograph’.

The CfAI are responsible for specific workpackages on the pickoff module and the integral field units. The slicers are based on the Advanced Image Slicer concept and use diamond-machined monolithic optics techniques developed at our in-house Precision Optics Laboratory to achieve the required throughput and image quality. The images below show preliminary designs of the pickoff module and the IFU optical design.

FURTHER INFORMATION

Design of the KMOS Multiple-object Integral Field Spectrograph
Sharples, R.M. et al.
Proc. SPIE 6269-49 (2006)
PDF Version

Surveying the High Redshift universe with KMOS
Sharples, R.M. et al.
ESO Messenger 122, 2-5 (2005)
PDF Version

KMOS: an Infrared Multiple-object Integral Field Spectrograph for the ESO VLT
Sharples, R.M. et al.
Proc. SPIE 5492, 1179-1186 (2004)
PDF Version

Executive Summary - Preliminary Design Phase
PDF Version

CONTACT PERSON

Prof. Ray Sharples