The Abu infrared imager consists of an ALADDIN 1024x1024 InSB array
mounted in a cold-head cooled dewar capable of pumping down to operational temperature without cryogens, equipped with one-to-one transfer optics and an eight-position filter wheel.
This simple system was operated at the South Pole on the CARA SPIREX telescope for two years, running in its second winter without trouble continuously for nine months. It was then modified slightly, mostly by inclusion of a higher quality ALADDIN II array, and used for commissioning of the Gemini South 8-meter telescope on Cerro Pachon in Chile.
We discuss the lessons learned from the South Pole experiment, the changes made for operations on Gemini South, some results from both sites, and the future of this compact, reliable, and robust camera.
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.
The Mayall 4-meter telescope on Kitt Peak is a successful and productive telescope now approaching its thirtieth anniversary. Originally designed at 150 inches, built at 158 inches, and with an effective aperture or 3.81m, it is from the generation of thick mirror, equatorially mounted telescopes. At a moderate altitude site, the Mayall had in the past upheld the prejudice that ground-based observing delivers about 1" seeing at best, and that it is no surprise to be considerably fuzzier. Changes in engineering, computer control, and our understanding of telescope seeing, have led to the new generation of lightweight mirrors with complex active support and advanced thermal control, running on altitude-azimuth mounts inside compact, low-volume enclosures. Such telescopes routinely deliver sub-arcsecond seeing, often down below 0.5" even from 'traditional' sites, and even sharper from higher and more remote sites to which access has been developed over recent decades. Nevertheless, what we have learned can be successfully applied to older telescopes: the Mayall telescope is a case in point, since it now regularly provides sub-arcsecond image quality. We discuss the significant improvements in thermal management and active control of the Mayall system over the last several years, as well as the difficulty of evaluating such changes, especially separating different effects. We also discuss future adjustments to and tuning of existing sub-systems, possible changes to the telescope environment, and planned new features. It takes effort and continual attention to detail, but older facilities can still be world class.
At the 1998 SPIE meeting we described a cryogenic, high- resolution spectrograph for use in the 1-5 micrometers region. At that time Phoenix had been used at Kitt Peak for about a year. In the intervening two years we have worked extensively with the instrument and have modified a few aspects of the design to bring the operational characteristics more closely into agreement with the original specifications. Changes to the instrument since 1998 that resulted in significant improvements in performance will be discussed. We will review the current operational characteristics of the spectrograph. Phoenix is a facility instrument of the National Optical Astronomy Observatory with use planned at Gemini South and CTIO.
ABU is a NOAO IR imaging camera designed for evaluating the performance of the 1024x1024 Aladdth InSb array. For this experiment, it was outfitted with five filters (see Figure 9) m the 3-5 micron range to exploit the low water vapor and lower air temperatures at the South Pole. At the South Pole it was integrated with the CARA SPIREX (South Pole Infrared Explorer) telescope. Figure 1 is a picture of the telescope showing the environmental box (the white box by the author). which protected ABU and its electronics from ambient environmental conditions.
The problem of grouping 3D coplanar line segmented obtained from a single view is addressed. The proposed method is efficient and has been tested on both synthetic and real images. First, a Hough-based algorithm is used to detect 2D line segments in a sequence of images representing a 3D scene. Secondly, the 3D coordinates of the line segments are estimated, at each time instant, by means of an extended Kalman filter, based on the displacements (u,v) of the line segment endpoints on the image plane. Finally, 3D coplanar segments are grouped by a 3D voting approach. The novelty of this method lies in the possibility of using a simple voting scheme similar to that associated with the standard Hough transform for line extraction, where each edge point votes for a sheaf of rectilinear lines. In the proposed approach, each line segment votes for a sheaf of planes.