The U.S. Virtual Astronomical Observatory (VAO) is a product-driven organization that provides new scientific
research capabilities to the astronomical community. Software development for the VAO follows a lightweight
framework that guides development of science applications and infrastructure. Challenges to be overcome include
distributed development teams, part-time efforts, and highly constrained schedules. We describe the process we
followed to conquer these challenges while developing <i>Iris</i>, the VAO application for analysis of 1-D astronomical
spectral energy distributions (SEDs). Iris was successfully built and released in less than a year with a team distributed
across four institutions. The project followed existing International Virtual Observatory Alliance inter-operability
standards for spectral data and contributed a SED library as a by-product of the project. We emphasize lessons learned
that will be folded into future development efforts. In our experience, a well-defined process that provides guidelines to
ensure the project is cohesive and stays on track is key to success. Internal product deliveries with a planned test and
feedback loop are critical. Release candidates are measured against use cases established early in the process, and
provide the opportunity to assess priorities and make course corrections during development. Also key is the
participation of a stakeholder such as a lead scientist who manages the technical questions, advises on priorities, and is
actively involved as a lead tester. Finally, frequent scheduled communications (for example a bi-weekly tele-conference)
assure issues are resolved quickly and the team is working toward a common vision.
The Spatially Phase Shifted Digital Speckle Pattern Interferometer (SPS-DSPI) is a speckle pattern interferometer in
which the four phase-shifted interferograms are captured simultaneously in a single image. Designed to measure thermal
distortions of large matte-surfaced structures for the James Webb Space Telescope (JWST) program, this metrology
instrument has been used in two major cryo-distortion tests. This report will describe how differences in the vibrational
motions of the test objects necessitated changes in basic algorithms. The authors also report operational upgrades,
quantification of uncertainty, and improvement of the software operability with a graphic interface. Results from the
tests of the JWST test structures are discussed as illustration.
The Astronomer Proposal Tool (APT) Exposure Time Calculator (ETC) is a generic Java library for performing ETC calculations. Currently it is primarily used by the web based ETCs supporting Hubble Space Telescope (HST) proposals at Space Telescope Science Institute (STScI). This paper describes the software architecutre, current and potential uses of this library.
<b>Specview</b> is a spectral visualization tool designed to provide easy simultaneous display and analysis of multiple 1-D spectrograms of the same astronomical source taken with different instruments. It is a standalone Java application that features, aside its main plotting capabilities, a spectral model fitting engine. This article describes its main features and some aspects of its internal design. The software can be downloaded from <b>http://specview.stsci.edu</b>.