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EMIR is a near-IR, multi-slit camera-spectrograph under development for the 10m GTC on La Palma. It will deliver up to 45 independent R equals 3500-4000 spectra of sources over a field of view of 6 feet by 3 feet, and allow NIR imaging over a 6 foot by 6 foot FOV, with spatial sampling of 0.175 inch/pixel. The prime science goal of the instrument is to open K-band, wide field multi-object spectroscopy on 10m class telescopes. Science applications range from the study of star-forming galaxies beyond z equals 2, to observations of substellar objects and dust-enshrouded star formation regions. Main technological challenges include the large optics, the mechanical and thermal stability and the need to implement a mask exchange mechanism that does not require warming up the spectrograph. EMIR is begin developed by the Instituto de Astrofisica de Canarias, the Instituto Nacional de Tecnica Aeroespacial, the Universidad Complutense de Madrid, the Observatoire Midi-Pyrennees, and the University of Durham. Currently in its Preliminary Design phase, EMIR is expected to start science operation in 2004.

The atmospheric refraction affects the position of objects in the sky in two ways: a chromatic effect and a field differential effect. The former is about the same in the field and can be, in principle, corrected using an Atmospheric Dispersion Compensator (ADC). The latter is dependent of the field size and cannot be corrected. For spectroscopy in wide fields, both effects have to be carefully considered because they affect the spectrophotometry in terms of signal to noise ratio and spectral distortions. The present study aims to evaluate the atmospheric effects in the case of the VIMOS instrument for the ESO VLT. It is shown that provided a careful operational mode the distortion of spectra can be kept at a level less than 15% with reasonable constraints.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present the current design of the VIsible Multi-Object Spectrograph (VIMOS) and the Near InfraRed Multi-Object Spectrograph (NIRMOS) for the European Southern Observatory Very Large Telescope. The basic scientific requirement is to conduct very deep redshift surveys of large quantities of objects, in a minimum number of nights. The technical specifications are to allow for a large multiplex gain over a wide field, and a high efficiency of the optical train, over the 0.37 to 1.8 micrometer domain. The baseline technical concept is built around 4 channels, covering 4 X 7 X 8 arcmin2 for VIMOS and 4 X 7 X 7 arcmin2 for NIRMOS. Each channel is an imaging spectrograph with a large field adaptation lens, a collimator, grisms or filters, and a F/1.8 camera, coupled to a 2048 X 4096 pixels CCD for VIMOS, and a 20482 HgCdTe Rockwell array for NIRMOS. The unique multiplex gain allows to obtain spectra of up to 840 object simultaneously with VIMOS, and up to 170 with NIRMOS (10 arcsec slits). An integral field spectroscopy mode with more than 6400 fibers coupled to micro-lenses will be available for VIMOS, covering a 1 X 1 arcmin2 field. The VLT-VIRMOS survey of more than 150,000 galaxies is planned down to magnitudes IAB equals 24, coupled to an ultra deep probe to IAB equals 26.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new cosmological test has been devised, based on QSO samples. Its sensitivity to the parent cosmology (Ω and Λ) and to the various other parameters has been checked with numerical simulations. In particular it is found that increasing the upper redshift limit is largely as efficient as increasing the sample size.

We present the status of the feasibility study of the Visible InfraRed Multi Object Spectrograph, conducted under contract with ESO for the VLT. The aim of this study is to establish the scientific objectives, identify the opto-mechanical concepts, and predict the performances of a wide-field multi-object spectrograph dedicated to the deepest galaxy and AGN redshift surveys that will be possible with the VLT. We have identified that a concept based on a four quadrant imaging-spectrograph, using multi-slit aperture plates, is the most efficient concept in this context. The maximum number of slits 10 arcseconds in length, that can be observed simultaneously, is in excess of 800, offering a spectacular multiplexing gain in a field of 4 × 7 × 8 arcmin2, for a wavelength coverage from 0.37 to 1.8μm. We are proposing a dedicated wide-field deep redshift survey, to collect ~ 105 galaxies brighter than I = 24, in the redshift range 0.3 4 or more, in less than 200 nights at one Nasmyth focus of the VLT. The timescale of the instrument development is expected to be 4 years, with first light in early 2001, provided that the VIRMOS concept is selected by ESO early in 1997.

VIRMOS, the Visible InfraRed Multi Object Spectrograph, is being studied under contract with ESO, to identify the opto-mechanical concepts, and predict the performances of a wide-field multi-object spectrograph dedicated to the deepest galaxy, large scale

Over the last decade, the quantity of scientific results brought by the observations of very faint objects has been quite spectacular. In particular, they concern the photometry of faint galaxies up to B = 27 (Tyson 1988) or K = 22 (Cowie et al. 1994). The consequences of these observations are the detection of a large population of faint galaxies more numerous than any prediction given by standard galaxy evolution and probably a new vision of the distant universe. For faint object spectroscopy, the most recent surveys of field galaxies reach a magnitude range of 23–24 (Colless et al. 1990, 1993, Lilly and Cowie 1993, Tresse et al. 1993) with a reasonable S/N ratio that allows a redshift measurement from absorption-line identification. But in this magnitude range, the sky background flux is dominant with respect to the source, being at least 10 times brighter. It is well known that in that case, with a low readout noise detector and a “perfect” spectrograph, the S/N ratio scales as

Summary :In this poster paper we shortly present recent developpment and preliminary results obtained with the focal reducer of the Canada French Hawai 3.6 meter telescope with new trends for deep imagery and multiaperture spectroscopy.

Many coronal transient exhibit a circular aspect, which has been interpreted up to now as a loop structure. From polarization measurements of the 10 August, 1973 transient observed by the ATM coronagraph, which allows the location of material away from the plane of the sky, we show that this particular transient is more likely to be a 3-dimensional, bubble-shaped structure, than a loop. The radial component of the speed is evaluated. A thin streamer close to the transient is displaced by its passage, both in the plane of the sky and in the direction perpendicular to it.

The electronic camera built by the Meudon Camera Group was used during three observational shifts at the prime focus at the Canada-France-Hawaii Telescope. The instrument is described and its performances given. The camera is used with S 11 photocathodes saved in the detector during several months under the protection of an all-metal valve. 30 pl/mm are resolved on the photocathode and on standard observations, the RMS noise does not exceed 7 e-/h/pixel. All camera functions (high voltage, plate commutation, time of exposure, etc.) are fully under control of a Z80 microprocessor. A phosphor screen located in the same plane as the nuclear plates is used to check the electronic and optical focusing on the telescope. The first observations led to a limiting magnitude of MV=25.2 (S/N=5) in one hour, with a 1.4" seeing. Current seeing of 1" in Hawaii will give access to mV=25.6 in one hour, mB=26.4 in two hours and mU=25.5 in one hour. Some examples, taken from different observational runs, are presented.

Properties related to the spatial continuity of electronographic data are shown. Performances are compared to those of sampling detectors such as CCDs. Applications are proposed where, resolution, large field and low noise are in favour of electronography.

A multiaperture spectroscopy device has been installed on the focal reducer at the Cassegrain focus of the Canada-France-Hawaii Telescope. The mask processing and ,positioning operations are described. Emphasis is placed on the speed and reliability of a fully automatic method controlled by a computer routine. Spectra obtained during the first observations at C.F.H.T. are shown as illustration.

First results have been obtained with an electronographic camera used at the prime focus of the C.F.H. Telescope in Hawaii. The camera is briefly described. It is an electronic camera with a new technological design and a tight valve allowing the recovery of the nuclear plates without destroying the photocathode. Some preliminary results are given.

Multi-object spectrography is widely used as a way to increase the effi¬ciency of telescopes. ESO and the CFHT have developed their own instruments for different applications. Several concepts of multi-object spectrography are reviewed. More details are given on a system called PUMA which has been implemented at ESO and the CFHT.

Publisher Summary This chapter provides an overview of electronic cameras used for space research. Two Lallemand cameras have been built for balloon-borne experiments, one using electrostatic and the other electromagnetic focusing. This chapter describes the camera built using electromagnetic focusing. As with previous models of the Lallemand camera, a new photocathode is needed after each pump down. The nuclear plates are inside the vacuum chamber, which has to be brought back to atmospheric pressure after each experiment to allow the recovery of the plates. The whole instrument is immersed in liquid helium during the experiment; the photocathode and the plates are thus cooled to a very low temperature, and there is a powerful cryopumping action inside the camera. A special technology has been used employing only stainless steel and alumina, instead of the traditional glass envelope, which would not be suitable for use in a balloon. In this study, the tests conducted with the electromagnetic tube together with the results obtained in the study of the superconducting solenoid and the calculation of electron trajectories encourage to start the design of an electromagnetically focused camera with a field 10 cm in diameter.

Publisher Summary This chapter discusses development of a new type of Lallemand camera. At the Imperial College Symposium, it was discussed to produce an electrostatic camera based on the Lallemand principle, but with a technology more suited to difficult operational conditions. The results obtained with a first prototype enabled researchers to begin fabrication of four-valve cameras. In this camera, the photocathodes are introduced into the camera following the Lallemand procedure. The valve is then closed tightly and the camera relieved of both its introduction appendages by pinching off two silver-plated copper tubes. The electronic tube with the photocathode may then stand as long as it is necessary before operation. In operation, the drum bearing the emulsions is attached under the valve unit, vacuum tightness being obtained by squashing an indium wire between camera and plate-holder flanges. Although nearly 100 closures were required to select the material and shape of the sealing parts, only 4 tests in the presence of the photocathode have been completed, with the last attempt being unsuccessful. It was found that the closing force was too high and the consequent slight deformation of the valve components finally prevented perfect leak tightness.

Publisher Summary This chapter discusses the performance of an electromagnetically focused image tube built in laboratory at Meudon Observatory. A superconducting coil was built that could produce a magnetic field of 7 kG. In the working part of the coil, the homogeneity is better than 0.2%. Compensating windings make it possible to achieve this high homogeneity with a rather short coil: the ratio between its length and its diameter is only 2.2, while the ratio between its length and the distance between the photocathode and the plate is only 2.5. During the tests, the overall potential was distributed between the electrodes by an external divider made up of 19 resistors, the values of which were known to within about 1%. The total voltage (20 kV) was provided by an electrostatic generator delivering a voltage with a stability of about 0.1%. The image distortion of this tube is extremely low and has a value of the same order as the limiting resolution. Calculations were confirmed by experimental data in every case and could be reliably used to design future cameras based on the same principle.

Publisher Summary This chapter provides an overview of the electronic camera used in a reflection mode. This mode of operation has the advantage of extending the spectral range in the ultraviolet and infrared parts of the spectrum when compared with classical transmission-mode image tubes. In the design of a “reflection-mode camera,” it is essential to prevent the screening of the photon flux by the electron receptor. As electrons are confined by magnetic lines of force, one possibility is to incline the accelerating electric field at an angle to the focusing magnetic field in an electromagnetically focused image tube. A model has been built to test the image quality of a reflection-mode camera. This model is operated in the transmission mode knowing that image quality is independent of the mode used. The results obtained with this model are very promising. Several plates have been taken showing a resolution of 40 lp/mm over almost the entire field and a maximum resolution of 90 lp/mm. It seems that the best resolution can be obtained in a direction perpendicular to the plane defined by the electric and magnetic fields.

The VIMOS VLT Deep Survey (VVDS) is underway to study the evolution of galaxies, large scale structures and AGNs, from the measurement of more than 100000 spectra of faint objects. We present here the results from the first epoch observations of more than 20000 spectra. The main challenge of the program, the redshift measurements, is described, in particular entering the ``redshift desert'' in the range $1.5, Comment: 8 pages, 7 figures, in the proceedings of IAU Symposium 216 "Maps of the Cosmos", Sydney, July 2003, M. Colless & L. Staveley-Smith Eds

Measurements of the growth rate of structure f at different redshifts can discriminate the origin of cosmic acceleration. Coupled to estimates of the expansion rate H(z) as provided by Type-la supernovae or Baryonic Acoustic Oscillations, accurate measurements of f(z) are able to distinguish "dark energy" models from theories with modified gravity, as, e.g., braneworld models. These two classes are degenerate when considering the expansion history alone. We have recently shown (Nature, 451 (2008) 541) that redshift-space distortions in the clustering pattern of galaxies measured from large redshift surveys represent an extremely promising technique to trace f (z) back in time. We have measured the distortion parameter beta at z similar to 0.8 using the currently largest field of the VVDS-Wide survey, that includes more than 10000 galaxy redshifts to I(AB) = 22.5 over 4 deg(2). We obtain 0 - 0.70 +/- 0.26, corresponding to a growth rate f = 0.91 +/- 0.36, consistent with the simplest cosmological-constant scenario. Error bars are still large compared with the difference among models. However, next-generation deep surveys with N > 100000 redshifts over similar to 100deg(2) or larger, will be able to use this test as an accurate probe of the origin of cosmic acceleration.

We discuss the evolution of clustering of galaxies in the Universe from the present epoch back to z ~ 2, using the first-epoch data from the VIMOS-VLT Deep Survey (VVDS). We present the evolution of the projected two-point correlation function of galaxies for the global galaxy population, as well as its dependence on galaxy intrinsic luminosities and spectral types. While we do not find strong variations of the correlation function parameters with redshift for the global galaxy population, the clustering of objects with different intrinsic luminosities evolved significantly during last 8-10 billion years. Our findings indicate that bright galaxies in the past traced higher density peaks than they do now and that the shape of the correlation function of most luminous galaxies is different from observed for their local counterparts, which is a supporting evidence of a non-trivial evolution of the galaxy vs. dark matter bias., Comment: 4 pages, 4 figures, to appear in the proceedings of the conference 'At the Edge of the Universe' (9-13 October 2006, Sintra, Portugal)