14 results on '"Kevin Tsubota"'
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2. Implementation of W. M. Keck Observatory's telescope control system upgrade
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Kevin Tsubota, Peter M. Thompson, Kevin McCann, Shui Kwok, Mike Pollard, Ben McCarney, Tomas Krasuski, and Ean James
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W. M. Keck Observatory ,business.industry ,Computer science ,law.invention ,Azimuth ,Telescope ,Tachometer ,Upgrade ,Control theory ,law ,Control system ,business ,Secondary mirror ,Computer hardware - Abstract
Launched in 2009, Keck Observatory’s Telescope Control System Upgrade (TCSU) project set out to improve Keck’s telescope pointing, tracking, and offsetting performance as well as increase maintainability and reliability. The project went online full time on the Keck 2 telescope in October 2017 and on the Keck 1 telescope in March 2018 after a notable delay due to a re-design of the azimuth and elevation encoder mounting systems. This paper discusses the details and challenges of implementing this large and complicated system while never requiring a shutdown of either telescope. The TCSU project replaced all of the major elements of the telescope controls, rotator and secondary mirror controls, and safety system. National Instrument’s reconfigurable I/O technology (i.e. NI RIO), with their embedded field programmable gate arrays (FPGAs), are used as the core of the telescope’s digital velocity control loop, structural filter, and tachometer filter. They were also used to create a monitoring and safety system for the rotator velocity controller as well as reading the newly installed tilt meters used to greatly improve pointing performance. Delta Tau’s family of “Brick” programmable multi-axis controllers, i.e. PMAC or BRICK, are used to control the rotator and secondary mirror. They enable better tuning and faster slew speeds for these subsystems. An Allen Bradley’s ControlLogix® controller and the family of FLEX™ Input/Output (IO) modules were used to create a distributed safety system able to handle a wide variety of signal types. This technology refresh based on commercial off the shelf equipment replaced much of our obsolete and custom equipment. A significant part of the project was the installation of new telescope azimuth and elevation position encoders based on Heidenhain’s 40 micron grading tape scales. Interpolated to a 10 nanometer resolution, the new encoders provide true 4 mas resolution in azimuth and 1 mas resolution in elevation. This is a big improvement to Keck’s position sensing when compared to the old rotary incremental encoders. The installation required a significant amount of mechanical infrastructure to house them. Additionally, two tilt meters were installed to sense the telescope’s varying vertical angle as a function of azimuth, mainly due to the azimuth bearing’s axial runout. The encoders and tilt meters are the primary reason for achieving the greatly improved pointing and tracking performance [1]. Finally, a switching solution using solid state relays and dual network switches was installed to provide seamless and rapid switching between the old and new control systems during commissioning. Although this component is a simple design and does not boast of any new technology, it is one of the key components that enabled the successful testing of the new equipment while keeping the old system operational as a backup for night time observing as well as for baseline performance comparisons. It allowed us to switch a variety of signal types and was very cost effective when compared to available products.
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- 2018
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3. Improving the pointing and tracking performance of the Keck telescopes
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James E. Lyke, Shui Hung Kwok, Kevin Tsubota, Tomas Krasuski, J.A.Mader, and Kevin McCann
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Physics ,business.industry ,Real-time computing ,Computer programming ,Astrophysics::Instrumentation and Methods for Astrophysics ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Tracking (particle physics) ,01 natural sciences ,law.invention ,010309 optics ,Telescope ,Upgrade ,law ,Control system ,0103 physical sciences ,Key (cryptography) ,Calibration ,0210 nano-technology ,business ,Encoder ,Simulation - Abstract
Pointing and tracking performance is one of the key metrics that characterize a telescope's overall efficiency. The pointing performance of the Keck telescopes, which use rotary friction encoders to provide position feedback to the control system, has been surpassed by newer large telescopes with more precise encoder systems. While poor tracking can be compensated with guiding, poor blind pointing performance can lead to loss of observing time. In this paper we present a history of the efforts to reduce the impact of poor pointing, as well as the improvements achieved after the installation of new tape encoders. We will discuss the calibration and testing methods and the tools for monitoring and maintaining the desired pointing performance. A comparative analysis of the pointing performance before and after the telescope control system upgrade will also be presented.
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- 2016
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4. Keck II Laser Guide Star AO System and Performance with the TOPTICA/MPBC Laser
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Kai Wei, Scott Lilley, Drew Medeiros, Jason C. Y. Chin, Greg W. Doppmann, Angel Otarola, Kevin Tsubota, Sam Ragland, Sylvain Cetre, Ed Wetherell, Peter Wizinowich, Marchetti, Enrico, Close, Laird M., and Véran, Jean-Pierre
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Physics ,Distributed feedback laser ,Dye laser ,business.industry ,Second-harmonic generation ,Physics::Optics ,Laser pumping ,Laser ,01 natural sciences ,law.invention ,010309 optics ,Laser guide star ,Optics ,law ,0103 physical sciences ,Optoelectronics ,Laser power scaling ,Physics::Atomic Physics ,business ,Adaptive optics ,010303 astronomy & astrophysics - Abstract
The Keck II Laser Guide Star (LGS) Adaptive Optics (AO) System was upgraded from a dye laser to a TOPTICA/MPBC Raman-Fibre Amplification (RFA) laser in December 2015. The W. M. Keck Observatory (WMKO) has been operating its AO system with a LGS for science since 2004 using a first generation 15 W dye laser. Using the latest diode pump laser technology, Raman amplification, and a well-tuned second harmonic generator (SHG), this Next Generation Laser (NGL) is able to produce a highly stable 589 nm laser beam with the required power, wavelength and mode quality. The beam’s linear polarization and continuous wave format along with optical back pumping are designed to improve the sodium atom coupling efficiency over previously operated sodium-wavelength lasers. The efficiency and operability of the new laser has also been improved by reducing its required input power and cooling, size, and the manpower to operate and maintain it. The new laser has been implemented on the telescope’s elevation ring with its electronics installed on a new Nasmyth sub-platform, with the capacity to support up to three laser systems for future upgrades. The laser is projected from behind the telescope’s secondary mirror using the recently implemented center launch system (CLS) to reduce LGS spot size. We will present the new laser system and its performance with respect to power, stability, wavelength, spot size, optical repumping, polarization, efficiency, and its return with respect to pointing alignment to the magnetic field. Preliminary LGSAO performance is presented with the system returning to science operations. We will also provide an update on current and future upgrades at the WMKO.
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- 2016
5. Keck telescope mount control redesign to improve short move performance
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Kevin Tsubota, Peter M. Thompson, Tomas Krasuski, and Jimmy Johnson
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Computer science ,Control (management) ,Open-loop controller ,Feed forward ,Telescope mount ,Simulation ,Mount - Abstract
The Keck I and II telescopes have been operational respectively since 1990 and 1996. Operational improvements are sought to decrease the settling time in response to short moves. The structural response of the open loop system has been re-identified and the mount control design has been re-examined. Changes to the mount control compensators and command shaping architecture have been proposed in order to achieve improved response. Results from these studies are presented, both theoretical and experimental.
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- 2014
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6. Laser guide star facility developments at W. M. Keck Observatory
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Sam Ragland, Scott Lilley, Thomas Stalcup, Drew Medeiros, Randy Campbell, Kai Wei, Jason C. Y. Chin, James E. Lyke, Rachel Rampy, Pete Tucker, Kevin Tsubota, Peter Wizinowich, E. Wetherell, and Sylvain Cetre
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Telescope ,Physics ,Laser guide star ,W. M. Keck Observatory ,law ,Fiber laser ,Astronomy ,Secondary mirror ,Adaptive optics ,Laser ,law.invention - Abstract
Laser Guide Star (LGS) facilities for adaptive optics (AO) have been in routine scientific operation on the Keck II and Keck I telescopes since 2004 and 2012, respectively. Two upgrades are currently in process for the Keck II LGS facility: moving the launch of the laser from the side of the Keck telescope to behind the secondary mirror and replacing the existing dye laser with a Raman-fiber amplifier (RFA) laser. Both of these upgrades are on the path to a multi-LGS facility for Keck’s next generation AO (NGAO) system. We will discuss the performance and operations experience with the existing LGS facilities with an emphasis on the newer Keck I LGS facility, the recently implemented Keck II center launch system and its initial on-sky results, the progress on the design and implementation of the new fiber laser, and the plans for a multi-LGS facility for NGAO.
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- 2014
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7. First faint dual-field phase-referenced observations on the Keck interferometer
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Sam Ragland, Rafael Millan-Gabet, K. Summers, E. Appleby, Julien Woillez, Andrew Cooper, Peter Wizinowich, Josh A. Eisner, Jörg-Uwe Pott, O. Martin, C. Felizardo, Kevin Tsubota, B. Smith, Drew Medeiros, John D. Monnier, T. Panteleeva, D. Morrison, Ed Wetherell, M. Mark Colavita, Rachel Akeson, C. Tyau, J. Herstein, Delplancke, Françoise, Rajagopal, Jayadev K., and Malbet, Fabien
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Physics ,Time delay and integration ,business.industry ,Phase (waves) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Laser ,law.invention ,Interferometry ,Optics ,Laser guide star ,law ,Magnitude (astronomy) ,Astronomical interferometer ,Astrophysics::Solar and Stellar Astrophysics ,Guide star ,Astrophysics::Earth and Planetary Astrophysics ,business ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Astrophysics::Galaxy Astrophysics - Abstract
Ground-based long baseline interferometers have long been limited in sensitivity by the short integration periods imposed by atmospheric turbulence. The first observation fainter than this limit was performed on January 22, 2011 when the Keck Interferometer observed a K=11.5 target, about one magnitude fainter than its K=10.3 limit. This observation was made possible by the Dual Field Phase Referencing instrument of the ASTRA project: simultaneously measuring the real-time effects of the atmosphere on a nearby bright guide star, and correcting for it on the faint target, integration time longer than the turbulence time scale are made possible. As a prelude to this demonstration, we first present the implementation of Dual Field Phase Referencing on the interferometer. We then detail its on-sky performance focusing on the accuracy of the turbulence correction, and on the resulting fringe contrast stability. We conclude with a presentation of early results obtained with Laser Guide Star AO and the interferometer., 10 pages, 12 figures, Proc. SPIE 2012
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- 2012
8. ASTRA: astrometry and phase-referencing astronomy on the Keck interferometer
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C. Felizardo, Kevin Tsubota, Rachel Akeson, Peter Wizinowich, James R. Graham, Julien Woillez, Josh A. Eisner, O. Martin, Ed Wetherell, C. Tyau, E. Appleby, John D. Monnier, Lynne A. Hillenbrand, M. Hrynevych, B. Berkey, J.-U. Pott, J. Herstein, Andrea M. Ghez, Sam Ragland, Rafael Millan-Gabet, T. Panteleeva, D. Medeiros, B. Smith, K. Summers, Andrew Cooper, D. Morrison, M. Mark Colavita, Danchi, William C., Delplanque, Françoise, and Rajagopal, Jayadev K.
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Physics ,Galactic Center ,Astrophysics::Instrumentation and Methods for Astrophysics ,Phase (waves) ,FOS: Physical sciences ,Astronomy ,Astrometry ,ASTRA ,01 natural sciences ,010309 optics ,Interferometry ,Upgrade ,0103 physical sciences ,Astronomical interferometer ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Spectral resolution ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
ASTRA (ASTrometric and phase-Referencing Astronomy) is an upgrade to the existing Keck Interferometer which aims at providing new self-phase referencing (high spectral resolution observation of YSOs), dual-field phase referencing (sensitive AGN observations), and astrometric (known exoplanetary systems characterization and galactic center general relativity in strong field regime) capabilities. With the first high spectral resolution mode now offered to the community, this contribution focuses on the progress of the dual field and astrometric modes., 10 pages, 6 figures, 2 tables, SPIE 2010
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- 2010
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9. Probing local density inhomogeneities in the circumstellar disk of a Be star using the new spectro-astrometry mode at the Keck interferometer
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Josh A. Eisner, C. Tyau, B. Smith, T. Panteleeva, D. Morrison, John D. Monnier, J.-U. Pott, James R. Graham, E. Appleby, K. Summers, Peter Wizinowich, C. Felizardo, Kevin Tsubota, M. Mark Colavita, M. Hrynevych, D. Medeiros, Ed Wetherell, Julien Woillez, Andrew Cooper, Sam Ragland, Rafael Millan-Gabet, B. Berkey, J. Herstein, Andrea M. Ghez, Rachel Akeson, and Lynne A. Hillenbrand
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Physics ,010504 meteorology & atmospheric sciences ,Be star ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrometry ,Astrophysics ,01 natural sciences ,Stars ,Gravitational potential ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Astronomical interferometer ,Astrophysics::Solar and Stellar Astrophysics ,Emission spectrum ,Astrophysics::Earth and Planetary Astrophysics ,Spectral resolution ,Astrophysics - Instrumentation and Methods for Astrophysics ,010303 astronomy & astrophysics ,Stellar evolution ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences - Abstract
We report on the successful science verification phase of a new observing mode at the Keck interferometer, which provides a line-spread function width and sampling of 150km/s at K'-band, at a current limiting magnitude of K'~7mag with spatial resolution of lam/2B ~2.7mas and a measured differential phase stability of unprecedented precision (3mrad at K=5mag, which represents 3uas on sky or a centroiding precision of 10^-3). The scientific potential of this mode is demonstrated by the presented observations of the circumstellar disk of the evolved Be-star 48Lib. In addition to indirect methods such as multi-wavelength spectroscopy and polaritmetry, the here described spectro-interferometric astrometry provides a new tool to directly constrain the radial density structure in the disk. We resolve for the first time several Pfund emission lines, in addition to BrGam, in a single interferometric spectrum, and with adequate spatial and spectral resolution and precision to analyze the radial disk structure in 48Lib. The data suggest that the continuum and Pf-emission originates in significantly more compact regions, inside of the BrGam emission zone. Thus, spectro-interferometric astrometry opens the opportunity to directly connect the different observed line profiles of BrGam and Pfund in the total and correlated flux to different disk radii. The gravitational potential of a rotationally flattened Be star is expected to induce a one-armed density perturbation in the circumstellar disk. Such a slowly rotating disk oscillation has been used to explain the well known periodic V/R spectral profile variability in these stars, as well as the observed V/R cycle phase shifts between different disk emission lines. The differential line properties and linear constraints set by our data lend support to the existence of a radius-dependent disk density perturbation., Comment: 28 pages, 4 figures, Accepted for publication by ApJ
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- 2010
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10. Astrometry with the Keck-Interferometer: the ASTRA project and its science
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T. Panteleeva, Bill Randolph, D. Morrison, James R. Graham, M. Mark Colavita, Rachel Akeson, Drew Medeiros, K. Summers, B. C. Berkey, Josh A. Eisner, C. Tyau, Kevin Tsubota, Michael Hrynewych, Andrew Cooper, John D. Monnier, Andrea M. Ghez, Lynne A. Hillenbrand, B. Smith, Jörg-Uwe Pott, Rafael Millan-Gabet, Julien Woillez, Ed Wetherell, Nevin N. Weinberg, Eliot Quataert, and Peter Wizinowich
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Physics ,Milky Way ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Astrometry ,Astrophysics ,ASTRA ,Black hole ,Stars ,Interferometry ,Upgrade ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
The sensitivity and astrometry upgrade ASTRA of the Keck Interferometer is introduced. After a brief overview of the underlying interferometric principles, the technology and concepts of the upgrade are presented. The interferometric dual-field technology of ASTRA will provide the KI with the means to observe two objects simultaneously, and measure the distance between them with a precision eventually better than 100 uas. This astrometric functionality of ASTRA will add a unique observing tool to fields of astrophysical research as diverse as exo-planetary kinematics, binary astrometry, and the investigation of stars accelerated by the massive black hole in the center of the Milky Way as discussed in this contribution., 22 pages, 10 figures (low resolution), contribution to the summerschool "Astrometry and Imaging with the Very Large Telescope Interferometer", 2 - 13 June, 2008, Keszthely, Hungary, corrected authorlist
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- 2008
11. Recent progress at the Keck Interferometer
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Peter Wizinowich, Rachel Akeson, Mark Colavita, John Gathright, Eric Appleby, Jim Bell, Ben Berkey, Andrew Booth, Heidi Brandenburg, Jason Chin, Wayne Dahl, Claude Felizardo, Jean Garcia, Scott Hartman, Jen Herstein, Michael Hrynevych, Chris Koresko, Robert Ligon, Rafael Millan-Gabet, Doug Morrison, Tatyana Panteleeva, Sam Ragland, Robert Smythe, Kellee Summers, Kevin Tsubota, Colette Tyau, Ed Wetherell, Julien Woillez, Monnier, John D., Schöller, Markus, and Danchi, William C.
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Physics ,Telescope ,Interferometry ,Optics ,law ,business.industry ,Astronomical interferometer ,Angular resolution ,business ,law.invention - Abstract
The Keck Interferometer (KI) combines the two 10m diameter Keck telescopes providing milliarcsecond angular resolution. KI has unique observing capabilities such as sensitive K-band V^2, L-band V^2 and N-band nulling modes. The instrument improvements and status of the Keck Interferometer since the 2010 SPIE meeting are summarized. We discuss the current capabilities of the KI, operational improvements, and the science from the KI during the past two years. We will conclude with a brief note on the closure of the KI facility. Details of dual field phase referencing developments and nulling science results are presented elsewhere at this conference.
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- 2006
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12. Outrigger telescopes for narrow-angle astrometry
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Craig Smith, Dennis McBride, J. Bell, James H. Kelley, Patricia Goude, Peter Wizinowich, Andy C. Rudeen, Gerard van Belle, Robert Brunswick, Kevin Tsubota, Kyle K. Kinoshita, James M. Walker, M. Hrynevych, John K. Little, and M. Mark Colavita
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Wavefront ,Physics ,business.industry ,Navigator Program ,Outrigger ,Astronomy ,Astrometry ,Exoplanet ,law.invention ,Telescope ,law ,Planet ,Astronomical interferometer ,Aerospace engineering ,business - Abstract
The NASA Outrigger Telescope Project is a ground-based component of NASA's Navigator Program. The proposed project would utilize four to six 1.8-meter telescopes with co-rotating domes configured as an interferometer. One of the project’s scientific goals is the detection of exoplanets, which would be accomplished with long baseline narrow-angle astrometry. This astrometry mode would be able to detect Uranus mass planets up to 60 light years away. The requirements of narrow-angle astrometry, both technically and operationally, levy requirements on the telescopes and enclosures, including, for example, wavefront quality, pivot stability, and slew speed. This paper will describe these requirements and how they were achieved in the design. It will also discuss the testing and verification of these requirements. Actual telescope performance as tested at EOS Technologies is presented elsewhere in these proceedings.
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- 2004
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13. Software engineering for the Keck II Telescope Control System
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Hilton Lewis, William Lupton, Allan Honey, Sarah Quady, and Kevin Tsubota
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Telescope ,Engineering ,Software ,business.industry ,Project commissioning ,law ,Control system ,Systems engineering ,First light ,Software engineering ,business ,Software project management ,law.invention - Abstract
The Keck II telescope control system is a completely new design from the Keck I system. The entire software project, design, implementation and commissioning, has taken 16 months from inception in January 1995 to completion of all major subsystems in April 1996. First light took place in January 1996, and scientific quality images were taken in April 1996. Full operations are planned for October 1996. This paper focuses on the management and software engineering practices and the software tools that made it possible to complete a project of this magnitude with the limited time and resources at our disposal. Areas of potential software sharing and collaboration with other observatories are also discussed.
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- 1997
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14. Keck II Telescope Control System
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Sarah Quady, William Lupton, Allan Honey, Kevin Tsubota, and Hilton Lewis
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Physics ,business.industry ,Optical engineering ,Electrical engineering ,Industrial control system ,First light ,law.invention ,Telescope ,Upload ,Software ,law ,Control system ,Systems engineering ,Adaptive optics ,business - Abstract
The experimental physics and industrial control system (EPICS) originated in the high energy physics community and has been used for several years to control accelerators. It is now in use or soon to be in use at several observatories around the world. In 1995, it was decided that Keck II telescope would have a new EPICS-based control system rather than use a copy of the Keck I system. This decision was made because it was felt that EPICS provided a superior software infrastructure to that developed for Keck I, and that it would scale well to encompass adaptive optics and eventual use of the two telescopes for interferometry. The new control system was developed throughout 1995 and the early part of 1996, leading to first light in January 1996, making it the first fully EPICS-controlled telescope control system in the world. This paper describes how EPICS has been used to implement the control system, including a detailed discussion of the axes control, pointing and timing system, and of how they interact with each other.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 1997
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