Edward J. Mannery

The Sloan Digital Sky Survey Photometric Camera

We have constructed a large-format mosaic CCD camera for the Sloan Digital Sky Survey. The camera consists of two arrays, a photometric array that uses 30 2048 × 2048 SITe/Tektronix CCDs (24 μm pixels) with an effective imaging area of 720 cm2 and an astrometric array that uses 24 400 × 2048 CCDs with the same pixel size, which will allow us to tie bright astrometric standard stars to the objects imaged in the photometric camera. The instrument will be used to carry out photometry essentially simultaneously in five color bands spanning the range accessible to silicon detectors on the ground in the time-delay–and–integrate (TDI) scanning mode. The photometric detectors are arrayed in the focal plane in six columns of five chips each such that two scans cover a filled stripe 25 wide. This paper presents engineering and technical details of the camera.

The 2.5 m Telescope of the Sloan Digital Sky Survey

We describe the design, construction, and performance of the Sloan Digital Sky Survey telescope located at Apache Point Observatory. The telescope is a modified two-corrector Ritchey-Chretien design with a 2.5 m, f/2.25 primary, a 1.08 m secondary, a Gascoigne astigmatism corrector, and one of a pair of interchangeable highly aspheric correctors near the focal plane, one for imaging and the other for spectroscopy. The final focal ratio is f/5. The telescope is instrumented by a wide-area, multiband CCD camera and a pair of fiber-fed double spectrographs. Novel features of the telescope include the following: (1) A 3° diameter (0.65 m) focal plane that has excellent image quality and small geometric distortions over a wide wavelength range (3000-10,600 A) in the imaging mode, and good image quality combined with very small lateral and longitudinal color errors in the spectroscopic mode. The unusual requirement of very low distortion is set by the demands of time-delay-and-integrate (TDI) imaging. (2) Very high precision motion to support open-loop TDI observations. (3) A unique wind baffle/enclosure construction to maximize image quality and minimize construction costs. The telescope had first light in 1998 May and began regular survey operations in 2000.

The multi-object, fiber-fed spectrographs for the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey

We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5 m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measure redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyα absorption of 160,000 high redshift quasars over 10,000 deg2 of sky, making percent level measurements of the absolute cosmic distance scale of the universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near-ultraviolet to the near-infrared, with a resolving power R = λ/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 nm < λ < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.

SCORPIUS XR-1: SOME X-RAY AND OPTICAL OBSERVATIONS (1969 MAY).

Simultaneous X ray and optical observations of Scorpius XR-1, comparing rocket data from various flights

Sloan digital sky survey 2.5-meter telescope: optics

The Sloan Digital Sky Survey 2.5-meter telescope optical design is optimized for wide field (3 degree(s)), broadband (300 nm to 1060 nm) CCD imaging and multi-fiber spectroscopy. The system has very low distortion, required for time-delay-and- integrate imaging, and chromatic aberration control, demanded for both imaging and spectroscopy. The Cassegrain telescope optics include a transmissive corrector consisting of two aspheric fused quartz optical elements in each configuration. The details of the fabrication of these elements are discussed. Included is the design, development and performance of custom optical coatings applied to these optics.

Design Of The Apache Point Observatory 3.5m Telescope II. Deformation Analysis Of The Primary Mirror

We have calculated the deflection of the surface of a 3.5 meter diameter borosilicate mirror using the finite element method. The mirror is a 0.46 m thick honeycomb structure with 25 mm thick face plates and 13 mm ribs. The cell spacing is 0.192 m and is regular except near the inner and outer perimeters. Axial support for the mirror will be provided by 48 air pistons. The air pressure in the pistons will be regulated to balance the axial component of the mirror weight. The axial air pistons are located near nodes in the rib pattern of the honeycomb thereby facilitating access to the interior of the mirror for ventilation and transverse support. A simple wind loading case was examined and the resulting deflections are shown to be small. The effects of thickness variations in fabrication of the mirror are presented and are small for the magnitudes of the variations expected. Several thermal load cases are described.

Support and Position Control of Primary and Secondary Mirrors for the Sloan Digital Sky Survey (SDSS) Telescope

The support and position control systems for both the primary and secondary mirror of the SDSS Telescope allow the mirrors up to 12 mm of precisely positioned axial motion, as well as limited tilt and transverse motion. This paper describes the final design and operation of these systems. Some relative strengths and limitations of the components and problems encountered with their implementation are also summarized.

The Performance of the Apache Point Observatory 3.5 M Telescope

The Astrophysical Research Consortium 3.5 m telescope facility on Apache Point (2800 m above sea level) near the National Solar Observatory in southern New Mexico is nearing completion. The telescope mount has been installed and testing and fabrication of remaining subassemblies are underway. The f/1.75 lightweight honeycomb primary mirror was cast April 1988 by the Steward Observatory Mirror Laboratory and is currently being figured.

Design Of The Apache Point Observatory 3.5m Telescope III. Primary Mirror Support System

We describe a system of pneumatic piston mirror supports for use in an altitude over azimuth telescope which react to gravity and wind loading. A pressure controller provides dynamic compensation of variable wind loading and changes in the gravity loading as a result of altitude angle changes. An active air circulation system which ventilates every honeycomb cell can be implemented without interference from the mirror supports. The system can be expanded in principle to accomodate 8 m honeycomb mirrors.

Design Of The Apache Point Observatory 3.5m Telescope IV. Optics Support And Azimuth Structures

The Apache Point Observatory 3.5 meter altitude-azimuth telescope features lightweight honeycomb optics, a fast f/1.75 primary figure, multiple on-line instrument capability and a control system designed for efficient remote operation. Friction coupled rollers drive the axes and couple the encoders. We have concentrated particularly on reducing local seeing effects by controlling heat in the vicinity of the telescope. Measures include mass reduction, emissivity control, insulation and forced ventilation.