Guy F.W. Woodhouse

The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, technical overview, and performance

The VISTA project was made possible by funding from the UK Joint Infrastructure Fund (JIF) and PPARC (later STFC).

The VISTA infrared camera

We describe the integration and test phase of the construction of the VISTA Infrared Camera, a 64 Megapixel, 1.65 degree field of view 0.9-2.4 micron camera which will soon be operating at the cassegrain focus of the 4m VISTA telescope. The camera incorporates sixteen IR detectors and six CCD detectors which are used to provide autoguiding and wavefront sensing information to the VISTA telescope control system.

Project overview of OPTIMOS-EVE: the fibre-fed multi-object spectrograph for the E-ELT

OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fibre fed multi object spectrograph proposed for the European Extremely Large Telescope (E-ELT), planned to be operational in 2018 at Cerro Armazones (Chile). It is designed to provide a spectral resolution of 6000, 18000 or 30000, at wavelengths from 370 nm to 1.7 μm, combined with a high multiplex (>200) and a large spectral coverage. Additionally medium and large IFUs are available. The system consists of three main modules: a fibre positioning system, fibres and a spectrograph. The recently finished OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT instrumentation studies, has been performed by an international consortium consisting of institutes from France, Netherlands, United Kingdom and Italy. All three main science themes of the E-ELT are covered by this instrument: Planets and Stars; Stars and Galaxies; Galaxies and Cosmology. This paper gives an overview of the OPTIMOS-EVE project, describing the science cases, top level requirements, the overall technical concept and the project management approach. It includes a description of the consortium, highlights of the science drivers and resulting science requirements, an overview of the instrument design and telescope interfaces, the operational concept, expected performance, work breakdown and management structure for the construction of the instrument, cost and schedule.

Characterization of VISTA IR detectors

VISTA awarded a contract to Raytheon Vision Systems in June 2002 to supply 16 SWIR HgCdTe 2Kx2K detectors. Raytheon has delivered VIRGO 2K x 2K readout multiplexers, engineering detectors and the first two science grade detectors. The UKATC has set up a low background test facility to test and characterize the VIRGO detectors and to confirm that the detector performance meets our specifications. The VIRGO 2Kx2K is a new detector being produced for VISTA by Raytheon. In this paper we present the first results and performance of the multiplexer and the science detector. The test facility includes a custom built low background close-cycle cooled cryostat, cryogenic pre-amplifier electronics and uses ESO’s Infrared array controller electronics and detector control and data acquisition software. The detector parameters being measured include trans-impedance conversion gain, quantum efficiency in J, H and K wave bands, read noise, dark generation rate, linearity, well capacity, pixel operability, drift with temperature, persistence and electrical cross-talk.

Developments on the UK FMOS project for the Subaru Telescope

We describe the UK participation in the FMOS project to provide multi-object IR spectroscopy for the Subaru telescope. The UK is working on the design of an OH suppression IR spectrograph, this work comprises the optical design, the opto-mechanical layout, spectrograph thermal environment and cryogenics and detector control system. We give a progress report on the current design work.

The current status of the UK-FMOS spectrograph

FMOS is a near-IR OH-suppressed multi-fibre fed spectrograph for the Subaru telescope. The spectrograph will accept 200 optical fibres from the ECHIDNA positioner system at the 30arcmin Prime focus of the telescope. We will describe the recent activities here in the UK in progressing the instrument from its conceptual phase through detailed design and into manufacture. A variety of technical areas will be described including: the opto-mechanical system design and construction, development of the HAWAII-II detector control system, the thermal system design & control and OH suppression techniques.

Aspects of concurrent design during the VISTA IR camera detailed design phase

As detailed instrument design progresses, judgements have to be made as to what changes to allow and when models such as thermal, stray-light and mechanical structure analysis have to be re-run. Starting from a well-founded preliminary design, and using good engineering design when incorporating changes, the design detailing and re-run of the models should bring no surprises. Nevertheless there are issues for maintaining the design and model configuration to a reasonably concurrent level. Using modern modeling software packages and foresight in setting up the models the process is made efficient, but at the same time the level of detail and number of cases now needed for instrument reviews is also large in order to minimise risks. We describe examples from the detailed instrument design of the VISTA IR Camera to illustrate these aspects and outline the design and analysis methods used.

CMOS Active Pixel Sensor Developments at the Rutherford Appleton Laboratory

This paper reports on an on-going research programme at the Rutherford Appleton Laboratory (RAL) to develop science-grade CMOS Active Pixel Sensors for space science missions in which compactness, low-mass, low-power, and greater radiation tolerance are advantageous.

Commissioning the VISTA IR camera

VISTA was designed as a survey facility, and was optimized for use with the 64Mpix VISTA IR Camera in the sense that the optical system of the instrument and telescope was designed as a single entity. The commissioning of the IR camera therefore formed a major part of the system integration and commissioning of the whole VISTA system. We describe some aspects of the commissioning process for VISTA, the interplay between the camera and telescope systems, and summarize the results of the verification phase.

256 Channel Data Acquisition System for VISTA Focal Plane to Readout Sixteen 2K×K Raytheon VIRGO Detectors

The ESO standard Infrared Array Control Electronics, IRACE, is used to read out the VISTA focal plane, which contains sixteen 2k x 2k VIRGO detectors. Each detector has 16 parallel video output channels. In total 256 video channels have to be processed resulting in a readout time for the complete focal plane of less than 1 sec. The IRACE system is modular and can be adapted for VISTA. It contains 27 VME size boards, which are distributed in three separate VME crates, Sixteen boards are ADC boards each board accommodating 16 video channels. All three boxes are connected by digital isolated differential signal cables to avoid any timing jitter and to trigger all of ADC’s simultaneously. An additional module had to be designed, which uses digital isolators to distribute the main signals like system clock, trigger pulse, reset signal and status bus control signals. The number cruncher of the data acquisition system needed for data capturing and preprocessing is realized by three high speed Linux-PC’s with dual 3 GHz CPU’s