The All-Sky camera used in the LSST and TMT site testing campaigns is described and some early results are shown. The All-Sky camera takes images of
the entire visible hemisphere of sky every 30s in blue, red, Y and Z filters giving
enhanced contrast for the detection of clouds, airglow and the near-infrared.
Animation is used to show movement of clouds. An additional narrow band filter
is centered on the most prominent line of the sodium vapor lamp spectra and is used to monitor any man-made light pollution near the site. The camera also
detects aircraft lights and contrails, satellites, meteor(ite)s, local light polluters,
and can be used for stellar extinction monitoring and for photometry of transient
astronomical objects. For outreach and education the All-Sky camera can show
wandering planets, diurnal rotation of the sky, the zodiacal light, and similar
We briefly describe the SOAR Optical Imager (SOI), the first light instrument for the 4.1m SOuthern Astronomical Research (SOAR) telescope now being commissioned on Cerro Pachón in the mountains of northern Chile. The SOI has a mini-mosaic of 2 2kx4k CCDs at its focal plane, a focal reducer camera, two filter cartridges, and a linear ADC. The instrument was designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope over a 5.5x5.5 arcmin2 field with high throughput down to the atmospheric cut-off, and close reproduction of photometric pass-bands throughout 310-1050 nm. During early engineering runs in April 2004, we used the SOI to take images as part of the test program for the actively controlled primary mirror of the SOAR telescope, one of which we show in this paper. Taken just three months after the arrival of the optics in Chile, we show that the stellar images have the same diameter of 0.74" as the simultaneously measured seeing disk at the time of observation. We call our image "Engineering 1st Light" and in the near future expect to be able to produce images with diameters down to 0.3" in the R band over a 5.5' field during about 20% of the observing time, using the tip-tilt adaptive corrector we are implementing.
The SOAR Telescope, near completion on Cerro Pachon - Chile, will carry Instrument Support Modules (ISMs) mounted at the two Nasmyth foci. Each ISM has three focal stations and is capable of making rapid instrument changes between them. Both ISMs also carry a Comparison Lamp System (CLS), guider and an acquisition camera, which are shared between the three instruments. One ISM supports IR instruments. The other is used for "Optical" instruments operating at wavelengths below 900nm. Beam steering mechanisms direct light from the SOAR science field or the CLS to the instrument in use. In the IR-ISM, light is sent to the lateral ports by dichroic mirrors which reflect IR and transmit wavelengths from 400-900nm to the guider. In the Optical-ISM, light is directed to the lateral ports by the use of first surface pick-off mirrors. Guiding is done off-axis. During operation, both ISMs can be rotated by 360° and must carefully control differential flexure between the guider and focal planes. A method of accurate relative flexure measurement has been developed where the ISM is rotated on its handling cart while carrying instrument mass simulators which reproduce its nominal payloads. In this paper, the ISM and its support sub-modules are described. Results of flexure measurements and tests of the CLS are provided.
Development of the 4.1 meter SOuthern Astrophysical Research (SOAR) Telescope is now complete. All baseline systems are in place and extensive commissioning activities have been performed with and without the primary optics installed in the telescope. The facility and dome have been under observatory operations and TCS control for a year of testing and tuning. The altitude over azimuth telescope mount was integrated on the mountain in a rapid 3-month period due to the complete assembly and testing performed at the factory prior to delivery. Early mount testing and successful integration into the Telescope Control System (TCS) without the optical system was accomplished on the sky through use of two separate small aperture telescopes fixed to the structure. One of these, the "feed telescope" was also pivotal in early testing of the calibration wavefront sensor and SOAR optical imager by directing focused light to these separate instruments. The SOAR optical system, with its 4.1 meter clear aperture, 100 cm thick, ULEtm primary mirror, its lightweight ULEtm secondary, and its fast tip tilt ULEtm tertiary has been delivered and installed in the telescope. This system was also assembled as an electrically connected system and individually optically tested under a visible interferometer at the factory enabling rapid integration and a short commissioning period on telescope. In this paper we present the project status, a summary of the commissioning period, and the performance data for the completed telescope and its major components.
Pushing the adaptive compensation of turbulence into the visible range remains a challenging task, despite the progress of AO technology. An AO system for SOAR, now under conceptual study, will be able to reach diffraction-limited resolution at 0.5-0.7 microns with natural guide stars as faint as magnitude 12, enabling studies of stellar vicinities for faint companions, nebulosity, etc. During the second stage of the project a Rayleigh laser guide star will be implemented. In this mode, only the lowest turbulent layers will be compensated. The angular resolution will be only two times better than natural seeing, but, in exchange, the uniformly compensated field will reach 2-3 arc-minutes, offering unique capabilities in crowded fields (clusters, nearby galaxies).
The Giant Segmented Mirror Telescope (GSMT), along with other proposed Extremely Large Telescopes (ELT's) with apertures over 20-m, is likely to impose rather different site selection criteria than those for existing large telescopes. Advantageously, remote-sensing techniques allow rather more objective comparisons than was possible in the past, and the general task is aided by numerical modeling and new ground-based measurement techniques. In recognition of the difficulty of the site-selection process, co-operation between the several ELT projects is the norm. A description is given of the site survey for the GSMT, begun in late 1999, and now part of the GSMT studies and evaluation project, run by the Associated Universities for Research in Astronomy (AURA) New Initiatives Office (NIO).
We describe the Nordic Optical Telescope's facility short- wavelength IR instrument, NOTCam. The instrument will be capable of wide-field and high-resolution imaging, long-slit and multi-object grism spectroscopy, coronography, and imaging-and spectro-polarimetry. First light will be in mid- 2000. Current progress is summarized and some problems we have encountered and overcome are discussed.