In preparation for the arrival of the Dark Energy Camera (DECam) at the CTIO Blanco 4-m telescope, both the hardware
and the software of the Telescope Control System (TCS) have been upgraded in order to meet the more stringent
requirements on cadence and tracking required for efficient execution of the Dark Energy Survey1. This upgrade was
also driven by the need to replace obsolete hardware, some of it now over half a century old.
In this paper we describe the architecture of the new mount control system, and in particular the method used to develop
and implement the servo-driver portion of the new TCS. This portion of the system had to be completely rethought,
when an initial approach, based on commercial off the shelf components, lacked the flexibility needed to cope with the
complex behavior of the telescope. Central to our design approach was the early implementation of extensive telemetry,
which allowed us to fully characterize the real dynamics of the telescope. These results then served as input to extensive
simulations of the proposed new servo system allowing us to iteratively refine the control model. This flexibility will be
important later when DECam is installed, since this will significantly increase the moving mass and inertia of the
Based on these results, a fully digital solution was chosen and implemented. The core of this new servo hardware is
modern cRIO hardware, which combines an embedded processor with a high-performance FPGA, allowing the
execution of LabVIEW applications in real time.
The Dark Energy Camera (DECam) has been installed on the V. M. Blanco telescope at Cerro Tololo Inter-American Observatory in Chile. This major upgrade to the facility has required numerous modifications to the telescope and improvements in observatory infrastructure. The telescope prime focus assembly has been entirely replaced, and the f/8 secondary change procedure radically changed. The heavier instrument means that telescope balance has been significantly modified. The telescope control system has been upgraded. NOAO has established a data transport system to efficiently move DECam's output to the NCSA for processing. The observatory has integrated the DECam highpressure, two-phase cryogenic cooling system into its operations and converted the Coudé room into an environmentally-controlled instrument handling facility incorporating a high quality cleanroom. New procedures to
ensure the safety of personnel and equipment have been introduced.
The adaptive module of the 4-m SOAR telescope (SAM) has been tested on the sky by closing the loop on
natural stars. Then it was re-configured for operation with low-altitude Rayleigh laser guide star in early 2011.
We describe the performance of the SAM LGS system and various improvements made during one year of on-sky
tests. With acceptably small LGS spots of 1.6′′ the AO loop is robust and achieves a resolution gain of almost
two times in the I band, under suitable conditions. The best FWHM resolution so far is 0.25′′ over the 3′ field
of the CCD imager.
We present a progress report on the SOAR Adaptive Module, SAM, including some results of tests of the Natural
Guide Star mode: image correction in the visible, performance estimates, and experiments with lucky imaging.
We have tested methods to measure the seeing and the AO time constant from the loop data and compared
the results to those of the stand-alone site monitor. Measurements of the instrument throughput and telescope
vibrations are given. We report progress on the Laser Guide Star system implementation, including tests of the
UV laser, test of the beam transfer optics with polarization control. We present the designs of the laser launch
telescope and laser wavefront sensor.
The SOAR Adaptive Module (SAM) will compensate ground-layer atmospheric turbulence, improving image
resolution in the visible over a 3'x3' field and increasing light concentration for spectroscopy. Ground layer
compensation will be achieved by means of a UV (355nm) laser guide star (LGS), imaged at a nominal distance
of 10km from the telescope, coupled to a Shack-Hartmann wave front sensor (WFS) and a bimorph deformable
mirror. Unique features of SAM are: access to a collimated space for filters and ADC, two science foci, built-in
turbulence simulator, flexibility to operate at LGS distances of 7 to 14 km as well as with natural guide stars
(NGS), a novel APD-based two-arm tip-tilt guider, a laser launch telescope with active control on both pointing
and beam transfer. We describe the main features of the design, as well as operational aspects. The goal is to
produce a simple and reliable ground layer adaptive optics system. The main AO module is now in the integration
and testing stage; the real-time software, the WFS, and the tip-tilt guider prototype have been tested. SAM
commissioning in NGS mode is expected in 2009; the LGS mode will be completed in 2010.
The adaptive optics instrument for the SOAR 4.1-m telescope will
improve the spatial resolution by 2-3 times at visible wavelengths, over a field of 3 arcmin, by sensing and correcting low-altitude turbulence selectively. We will use a Rayleigh laser guide star to accomplish this. We present the laser guide star design with predictions of system performance based on real turbulence statistics and telescope properties, sky coverage and some opto-mechanical aspects of the AO module. Various design trade-offs are discussed.
The Infrared Side Port Imager ISPI is a facility infrared imager for
the CTIO Blanco 4-meter telescope. ISPI has the following capabilities: 1-2.4 micron imaging with an 2K x 2K HgCdTe array, 0.3
arcsec/pixel sampling matched to typical f/8 IR image quality of ~0.6
arcsec and a 10.5 x 10.5 arcmin field of view. First light with ISPI
was obtained on September 24 2002, and since January 2003 ISPI has
been in operation as a common user instrument. In this paper we discuss operational aspects of ISPI, the behavior of the array and we report on the performance of ISPI during the first one and half year of operation.
The new operations model for the CTIO Blanco 4-m telescope will use a small suite of fixed facility instruments for imaging and spectroscopy. The Infrared Side Port Imager, ISPI, provides the infrared imaging capability. We describe the optical, mechanical, electronic, and software components of the instrument. The optical design is a refractive camera-collimator system. The cryo-mechanical packaging integrates two LN2-cooled dewars into a compact, straightline unit to fit within space constraints at the bent Cassegrain telescope focus. A HAWAII 2 2048 x 2048 HgCdTe array is operated by an SDSU II array controller. Instrument control is implemented with ArcVIEW, a proprietary LabVIEW-based software package. First light on the telescope is planned for September 2002.
Phoenix, a high resolution near-infrared spectrograph build by NOAO, was first used on the Gemini South telescope in December 2001. Previously on the Kitt Peak 2.1 and 4 meter telescopes, Phoenix received a new detector, as well as modified refrigeration, mounting, and handling equipment, prior to being sent to Gemini South. Using a two-pixel slit the resolution is ~75,000, making Phoenix the highest resolution infrared spectrograph available on a 6-10 meter class telescope at the current time. Modifications to and performance of the instrument are discussed. Some results on Magellanic cloud stars, brown dwarf stars, premain-sequence objects, and stellar exotica are reviewed briefly.
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.