Alan Moorwood European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching
astronomy, infrared, instrumentation
Current status of the project is that first light of the first 8.2m Unit Telescope was achieved on 25th May 1998. The FWHM 0.32'' visible images obtained and shown at this Workshop clearly demonstrate the excellent quality of both the telescope and the site. Science Verification with a visible test camera is planned for the second half of August after which the first major instrument, FORS ( visible imaging, polarimetry, spectroscopy and MOS spectroscopy) will be installed. The first IR instrument, ISAAC (1-5m imaging, polarimetry and spectroscopy), which has been built at ESO, will be installed in November 1998. Both of these instruments will be finally commissioned and used for Science Verification observations in early 1999 and made available to visiting astronomers in April 1999. With regard to the regular operation of the VLT it should be noted that ESO is also developing a complete data flow system comprising instrument simulators, software for pre-preparing observation/instrument sequences in the form of Observation Blocks, flexible scheduling software, data and calibration pipelines and an archive. At the beginning it is expected that about 50 of the observing will be performed by ESO in service mode and the rest with the visiting astronomer present at the Observatory. For those interested, more comprehensive information on the VLT and its instruments can be found on ESO's Web Site (http://www.eso.org/instruments/).
The already approved infrared instruments for the VLT are:
ISAAC: 1-5m Infrared Spectrometer and Array Camera (P.I. A. Moorwood, ESO) which is currently undergoing final testing in Garching prior to shipment to Paranal in June for installation at UT1 in Nov 1998. A derivative 1-2.5m instrument, SOFI, is already in operation at the 3.5m NTT telescope on La Silla (Moorwood, Cuby and Lidman, 1998, The Messenger, 91,9).
CONICA: Coude Near Infrared Camera (P.I. R. Lenzen, MPIA, Heidelberg) - an historical name as this instrument will be used for diffraction limited 1-5m imaging, polarimetry and spectroscopy with the NAOS, Nasmyth Adaptive Optics System on UT1 (P.I. G. Rousset, ONERA ). The two systems will be integrated in Europe in late 1999 and installed at the VLT in mid-2000.
SINFONI: Single Far Object Near IR Investigation (P.I. N. Thatte, MPIE, Garching) which will be used with the ESO developed MACAO AO system (P.I. D. Bonaccini, ESO) for integral field spectroscopy. SINFONI will be used by the MPIE first at Calar Alto and then transferred to the VLT in 2001.
NIRMOS: Near IR Multi-Object Spectrometer (P.I. O. Le Fèvre, LAS. Marseille ) for 1-1.8m wide field imaging and spectroscopy at R 2500 of up to 170 objects simultaneously. This instrument is in the detailed design phase together with its twin visible instrument VIMOS. It will be installed in 2001.
CRIRES: Cryogenic IR Echelle Spectrometer (P.I. G. Wiedemann, ESO) for very high (105) resolution IR spectroscopy, probably in combination with a MACAO type curvature sensing AO system. Is in detailed design phase and with aim of exploiting many of the ISAAC technical developments. To be installed in 2002.
VISIR: VLT Mid Infrared Imager Spectrometer (P.I. P.-O. Lagage, SAp, Saclay) for 8-27m imaging and spectroscopy.
A brief overview of the main instrumental modes is given in Table 1. Taken together, they cover a large fraction of the spatial and spectral resolution phase space with multi-object and integral field capabilities entering as major new modes opened up with the development of large format IR array detectors.
In addition, three interferometric instruments are at the conceptual design stage - AMBER (1-2.5m imaging/spectroscopy), MIDI(8-13m) and PRIMA (2-5m phase referenced imaging and astrometry).
In all cases, the IRACE acquisition system, developed by ESO initially for ISAAC will probably be used. It is a modular (nominally 32 channel) high speed (20 Mpix/s), low noise (limited by detector) system employing a GByte/sec link and an Ultrasparc processor for image pre-processing (Meyer et al., 1997, The Messenger, 86, 14). Although most modes will be background limited, it is expected that some modes involving the highest spatial and spectral resolution in the near infrared will reach the limits set by the intrinsic detector noise and dark current which are now at the incredible level of only a few e- and around 20e-/hour respectively as measured on Rockwell Hawaii arrays with IRACE.
The combined instrument complement of the VLT provides for a wide
range of visible and infrared capabilities from deep imaging and
spectroscopic surveys to high spatial and spectral resolution
observations of individual objects using adaptive optics and
interferometry. Science objectives are therefore expected to embrace
much of contemporary astronomy and the following is only a brief
summary of some of the currently envisaged science areas in which
infrared observations are expected to be of particular importance.
Large scale structure. Surveys for high z clusters and evolution of structures at z 3. Measurement of dynamics to constrain the formation epoch and distortions in the expansion field to map dark matter and the total mass density of the Universe. (NIRMOS, ISAAC).
Cosmological parameters. Distances from Cepheids and relative distances from fundamental plane and Tully - Fisher scaling relations and supernovae. Time delay in gravitationally lensed quasars. Refine values for H0, q0 and (CONICA, SINFONI, ISAAC).
High redshift galaxies. Galaxy formation and evolution. Photometric redshift (in combination with visible) and emission line surveys (Ly, H, [OII]) plus follow-up spectroscopy to determine star formation rate as a function of z, size, morphology, mass (ISAAC, NIRMOS, CONICA, SINFONI).
Gamma-ray bursts. Spectroscopy of optical counterparts (ISAAC, CONICA, SINFONI).
Galaxy nuclei. Stellar populations/dynamics. Black hole masses. Test unified AGN theories. Quasar host galaxies. (CONICA, SINFONI, VISIR, VLTI).
Stars. Abundances, circumstellar shells, mass loss, magnetic fields (CRIRES, VISIR).
Star formation. Measure IMF to lowest masses in star forming clusters. Outflows and dynamics of protostellar discs (ISAAC, CONICA, SINFONI, CRIRES, VISIR).
Extrasolar planets. Direct detection by imaging and/or velocity modulation of planetary spectral features (CRIRES, CONICA, VISIR, VLTI).
Protoplanetary systems. Thermal imaging of protoplanetary discs (VISIR, CONICA, VLTI).
Solar system. Composition and dynamics of planetary atmospheres. Detection, chemistry and mineralogy of faint outer solar system bodies (ISAAC, CONICA, SINFONI, VISIR).