Kim Gillies

Defining common software for the Thirty Meter Telescope

The software for the Thirty Meter Telescope (TMT) is currently in the specification and design phase. A decision was made early on to provide a common software package that will provide basic infrastructure and services to be used by all project software packages. A roadmap for defining Common Software was written. The first roadmap step of defining what should be included in common software was accomplished by analyzing similar projects. The result was the definition of a reference architecture for end-to-end observatory software systems called the Observatory Software Domain Architecture. This architecture was then used to define the specifications for the TMT common software. This paper describes the roadmap, the reference architecture, and the current definition of TMT common software.

Enabling technologies and constraints for software sharing in large astronomy projects

The new observatories currently being built, upgraded or designed represent a big step up in terms of complexity (laser guide star, adaptive optics, 30/40m class telescopes) with respect to the previous generation of ground-based telescopes. Moreover, the high cost of observing time imposes challenging requirements on system reliability and observing efficiency as well as challenging constraints in implementing major upgrades to operational observatories. Many of the basic issues are common to most of the new projects, while each project also brings an additional set of very specific challenges, imposed by the unique characteristics and scientific objectives of each telescope. Finding ways to share the solution and the risk for these common problems would allow the teams in the different projects to concentrate more resources on the specific challenges, while at the same time realizing more reliable and cost efficient systems. In this paper we analyze the many dimensions that might be involved in sharing and re-using observatory software (e.g. components, design, infrastructure frameworks, applications, toolkits, etc.). We also examine observatory experiences and technology trends. This work is the continuation of an effort started in the middle of 2007 to analyze the trends in software for the control systems of large astronomy projects.

A new approach for instrument software at Gemini

Gemini Observatory is now developing its next generation of astronomical instruments, the Aspen instruments. These new instruments are sophisticated and costly requiring large distributed, collaborative teams. Instrument software groups often include experienced team members with existing mature code. Gemini has taken its experience from the previous generation of instruments and current hardware and software technology to create an approach for developing instrument software that takes advantage of the strengths of our instrument builders and our own operations needs. This paper describes this new software approach that couples a lightweight infrastructure and software library with aspects of modern agile software development. The Gemini Planet Imager instrument project, which is currently approaching its critical design review, is used to demonstrate aspects of this approach. New facilities under development will face similar issues in the future, and the approach presented here can be applied to other projects.

The Infrared Imaging Spectrograph (IRIS) for TMT: motion planning with collision avoidance for the on-instrument wavefront sensors

The InfraRed Imaging Spectrograph (IRIS) will be a first-light client instrument for the Narrow Field Infrared Adaptive Optics System (NFIRAOS) on the Thirty Meter Telescope. IRIS includes three configurable tip/tilt (TT) or tip/tilt/focus (TTF) On-Instrument Wavefront Sensors (OIWFS). These sensors are positioned over natural guide star (NGS) asterisms using movable polar-coordinate pick-ofi arms (POA) that patrol an approximately 2-arcminute circular field-of-view (FOV). The POAs are capable of colliding with one another, so an algorithm for coordinated motion that avoids contact is required. We have adopted an approach in which arm motion is evaluated using the gradient descent of a scalar potential field that includes an attractive component towards the goal configuration (locations of target stars), and repulsive components to avoid obstacles (proximity to adjacent arms). The resulting vector field is further modified by adding a component transverse to the repulsive gradient to avoid problematic local minima in the potential. We present path planning simulations using this computationally inexpensive technique, which exhibit smooth and efficient trajectories.

Observatory software for the Thirty Meter Telescope (TMT)

The Thirty Meter Telescope (TMT) project is a partnership between the Association of Canadian Universities for Research in Astronomy (ACURA), Associated Universities for Research in Astronomy (AURA), Caltech and the University of California. The complexity of TMT and its diverse suite of instrumentation (many of which will be assisted by adaptive optics front-ends) necessitates the design and implementation of a highly-automated, well-tuned observatory software system. The fundamental system requirements are low operating costs and excellent reliability, both of which necessitate simplicity in software design. This paper will address how these requirements will be achieved as well as how the system will handle observing program execution.

Science planning for the Gemini 8-m telescopes

The new 8-meter class telescopes represent large investments by the development communities. This means that these telescopes must be operated efficiently to provide the best possible return on these investments and a great deal of effort has been made to provide control software that supports effective use of the telescopes. However, efficient use must be more than just keeping the telescopes operating; it is important that observers be provided tools that enable them work effectively. The Gemini 8 m Telescopes have developed a strategy for helping astronomers plan observations through the design of science programs. While there are a number of unique aspects to this strategy, this paper focuses on the methods used as the foundation for connecting astronomers to the facilities of the observatories during the design of science programs. The methods under development take advantage of emerging Internet technologies to help reduce the maintenance issues normally associated with supporting remote sites, while freeing users from many of the performance problems associated with web-based solutions.

The Infrared Imaging Spectrograph (IRIS) for TMT: closed-loop adaptive optics while dithering

The InfraRed Imaging Spectrograph (IRIS) is the first-light client instrument for the Narrow Field Infrared Adaptive Optics System (NFIRAOS) on the Thirty Meter Telescope (TMT). IRIS includes three natural guide star (NGS) On-Instrument Wavefront Sensors (OIWFS) to measure tip/tilt and focus errors in the instrument focal plane. NFIRAOS also has an internal natural guide star wavefront sensor, and IRIS and NFIRAOS must precisely coordinate the motions of their wavefront sensor positioners to track the locations of NGSs while the telescope is dithering (offsetting the telescope to cover more area), to avoid a costly re-acquisition time penalty. First, we present an overview of the sequencing strategy for all of the involved subsystems. We then predict the motion of the telescope during dithers based on finite-element models provided by TMT, and finally analyze latency and jitter issues affecting the propagation of position demands from the telescope control system to individual motor controllers.

The Infrared Imaging Spectrograph (IRIS) for TMT: advancing the data reduction system

Infrared Imaging Spectrograph (IRIS) is the first light instrument for the Thirty Meter Telescope (TMT) that consists of a near-infrared (0.84 to 2.4 micron) imager and integral field spectrograph (IFS) which operates at the diffraction-limit utilizing the Narrow-Field Infrared Adaptive Optics System (NFIRAOS). The imager will have a 34 arcsec x 34 arcsec field of view with 4 milliarcsecond (mas) pixels. The IFS consists of a lenslet array and slicer, enabling four plate scales from 4 mas to 50 mas, multiple gratings and filters, which in turn will operate hundreds of individual modes. IRIS, operating in concert with NFIRAOS will pose many challenges for the data reduction system (DRS). Here we present the updated design of the real-time and post-processing DRS. The DRS will support two modes of operation of IRIS: (1) writing the raw readouts sent from the detectors and performing the sampling on all of the readouts for a given exposure to create a raw science frame; and (2) reduction of data from the imager, lenslet array and slicer IFS. IRIS is planning to save the raw readouts for a given exposure to enable sophisticated processing capabilities to the end users, such as the ability to remove individual poor seeing readouts to improve signal-to-noise, or from advanced knowledge of the point spread function (PSF). The readout processor (ROP) is a key part of the IRIS DRS design for writing and sampling of the raw readouts into a raw science frame, which will be passed to the TMT data archive. We discuss the use of sub-arrays on the imager detectors for saturation/persistence mitigation, on-detector guide windows, and fast readout science cases (< 1 second).

The Infrared Imaging Spectrograph (IRIS) for TMT: data reduction system

IRIS (InfraRed Imaging Spectrograph) is the diffraction-limited first light instrument for the Thirty Meter Telescope (TMT) that consists of a near-infrared (0.84 to 2.4 μm) imager and integral field spectrograph (IFS). The IFS makes use of a lenslet array and slicer for spatial sampling, which will be able to operate in 100’s of different modes, including a combination of four plate scales from 4 milliarcseconds (mas) to 50 mas with a large range of filters and gratings. The imager will have a field of view of 34×34 arcsec2 with a plate scale of 4 mas with many selectable filters. We present the preliminary design of the data reduction system (DRS) for IRIS that need to address all of these observing modes. Reduction of IRIS data will have unique challenges since it will provide real-time reduction and analysis of the imaging and spectroscopic data during observational sequences, as well as advanced post-processing algorithms. The DRS will support three basic modes of operation of IRIS; reducing data from the imager, the lenslet IFS, and slicer IFS. The DRS will be written in Python, making use of open-source astronomical packages available. In addition to real-time data reduction, the DRS will utilize real-time visualization tools, providing astronomers with up-to-date evaluation of the target acquisition and data quality. The quick look suite will include visualization tools for 1D, 2D, and 3D raw and reduced images. We discuss the overall requirements of the DRS and visualization tools, as well as necessary calibration data to achieve optimal data quality in order to exploit science cases across all cosmic distance scales.

Design for a phase 0 network

Todays astronomers may use the telescopes and instruments of many observatories to execute their science observations. Discovering the distributed resources that are available is time consuming and error prone because astronomers must manually take facility information and match it to the needs of their science observations. While Phase 1 and Phase 2 of the proposal process are well supported by a wide variety of software tools, the initial phase of discovering what resources are available, Phase 0, suffers from a lack of software support. This paper describes and proposes the creation of a Phase 0 Network to fill this void. The network is built upon peer-to-peer (P2P) technology, showing that this new approach to distributed computing has viable uses in astronomy.