Spitzer data at the NASA/IPAC Infrared Science Archive (IRSA)

The NASA/IPAC Infrared Science Archive (IRSA) curates and serves science data sets from NASA’s infrared and submillimeter projects and missions, including IRAS, 2MASS, MSX, SWAS, ISO, IRTS and from the Spitzer Space Telescope. All Spitzer data can be accessed from IRSA’s Spitzer mission page at: http://irsa.ipac.caltech.edu/Missions/spitzer.html Spitzer Legacy Enhanced Products along with ancillary data are delivered in six month intervals starting from Fall 2004, until Fall 2006. IRSA continually ingests the Spitzer data and the ancillary data, and these data are made accessible through IRSA’s query engines. Legacy products for the C2D, FEPS, GLIMPSE, GOODS, SINGS and SWIRE projects are accessible through a common interface http://irsa.ipac.caltech.edu/applications/Atlas. This engine returns the spatial footprints of observations and provides access to all flavors of released data sets, including, where appropriate, previews of image mosaics, 3-color image mosaics and spectra

A New Approach to Tagging Data in the Astronomical Literature

Data Tags are strings used in journals to indicate the origin of the archival data and to enable the reader to recover the data. The NASA/IPAC Infrared Science Archive (IRSA) has recently introduced a new approach to production of data tags and recovery of data from them. Many of the data access services at the IRSA return filtered data sets (such as subsets of source catalogs) and dynamically created products (such as image cutouts); these dynamically created products are not saved permanently at the archive. Rather than tag the data sets from which the query result sets are drawn, the archive tags the query that generates the results. A single tag can, then, encode a complex dynamic data set and simplifies the embedding of tags in manuscripts and journals. By logging user queries and all the parameters for those query as Data Tags, IRSA can re-create the query and rerun the IRSA service using the same search parameters used when the Data Tag was created. At the same time, the logs give a simple count of the actual numbers of queries made to the archive, a powerful metric of archive usage unobtainable from the Apache web server logs. Currently, IRSA creates tags for queries to more than 20 data sets, including the Infrared Astronomical Satellite (IRAS), Cosmic Evolution Survey (COSMOS) and Spitzer Space Telescope Legacy Data Sets. These tags are returned by the spatial query engine, Atlas. IRSA plans to create tags for queries to the rest of its services in late Spring 2007. The archive provides a simple web interface which recovers a data set that corresponds to the input data tag. Archived data sets may evolve in time due to improved calibrations or augmentations to the data set. IRSA’s query based approach guarantees that users always receive the best available data sets

A Case Study in Modernizing Software: The IRAS Scan Processing and Integration Tool (“Scanpi”)

The all-sky far-infrared sky survey performed by the Infrared Astronomical Satellite (IRAS), launched in 1983, remains of exceptional value in astronomy. A tool developed during the IRAS mission, the Scan Processing and Integration Tool (Scanpi) has proven indispensable in maximizing the scientific value of the IRAS data. It performs weighted average fluxes of 1-dimensional (in-scan) IRAS raw survey scans; these averages provide sensitivity gains of 2–5 over the IRSA Point Source Catalog (PSC) in the fluxes of extended, confused or faint sources. It has recently been used in research areas as diverse as searches for planetary debris disks and star formation in low surface brightness galaxies. The aging code, now under maintenance at the NASA/IPAC Infrared Science Archive (IRSA), has proved ever more difficult to maintain and build. Scanpi was written in FORTRAN66, and over the years became unwieldy with the addition of wrappers and patches to keep apace with changing platforms. In 2007, IRSA delivered a modernized version of Scanpi, designed for long term maintenance and offering new functionality. Scanpi1 was rewritten in C and deployed on a Linux server. A major part of the development was to integrate Scanpi into the IRSA software architecture, which has been in operations for nine years, has supported over 22 million queries and is under active maintenance. Scanpi is written largely in C for performance and maintainability, and supports VO protocols. The architecture is designed as a set of stand-alone and reusable modules with simple program interfaces. Thus existing modules which perform tasks such as coordinate transformations and table filtering have been incorporated into Scanpi. We describe lessons learned and list best practices for modernizing software

RADAR: A Fast, Scalable, and Distributable Archive Inventory Service

The NASA/IPAC Infrared Science Archive (IRSA) has recently deployed the Recursive Archive Digest and Reference (RADAR) service, which returns an inventory of IRSA's holdings in response to a spatial query, and offers one-click download of data and links to IRSA's data access services. RADAR also supports inventories and data access from remote archives; the current implementation supports access to the Multi-mission Archive at STScI (MAST) Spectral and Image Scrapbook and NEDBasic Data. When complete, RADAR will maintain the results of multiple queries in "data collections" and will provide tools that will allow users to augment collections, remove data from them, modify search criteria, resubmit jobs, and check job status. RADAR is supported by an evolution of IRSA's component based architecture. It utilizes a fast estimation service and runs under the Request Management Environment (ROME) funded by NVO

The Measurement of Astronomical Parallaxes With CCD Imaging Cameras on Small Telescopes

Small telescopes equipped with charge-coupled device (CCD) imaging cameras are well suited to introductory laboratory exercises in positional astronomy (astrometry). An elegant example is the determination of the parallax of extraterrestrial objects, such as asteroids. For laboratory exercises suitable for introductory students, the astronomical hardware needs are relatively modest, and under the best circumstances, the analysis requires little more than arithmetic and a microcomputer with image display capabilities. Results from the first such coordinated parallax observations of asteroids ever made are presented. In addition, procedures for several related experiments, involving single-site observations and/or parallaxes of earth-orbiting artificial satellites, are outlined

Long Term Preservation of Data Analysis Software at the NASA/IPAC Infrared Science Archive

The NASA/IPAC Infrared Science Archive (IRSA) curates both data and analysis tools from NASA's infrared missions. As part of our primary goal, we provide long term access to mission-specific software from projects such as IRAS and Spitzer. We will review the efforts by IRSA (and within the greater IPAC before that) to keep the IRAS and Spitzer software tools current and available. Data analysis tools are a vital part of the Spitzer Heritage Archive. The IRAS tools HIRES and SCANPI have been in continual use since the 1980's. Scanpi offers a factor of 2 to 5 gain in sensitivity over the IRAS Point Source Catalog by performing 1D scan averaging of raw survey data at specified arbitrary position. In 2007 SCANPI was completely modernized, with major code revisions. HIRES returns IRAS survey images with higher resolution than the IRAS Sky Survey Atlas (ISSA). We are currently undertaking a modest revision to the tool to ensure continued reliability. In the next two years, the US Planck Data Center plans to adapt both tools for use with Planck data, and deliver them to IRSA for long term curation

The NASA/IPAC Infrared Science Archive (IRSA): The Demo

This paper describes the services available at the NASA/IPAC Infrared Science Archive (IRSA). Currently there are nearly 250,000 data requests a month, taking advantage of IRSA's data repository which includes 660 million sources (60 catalogs), 10 million images (22 image sets; 10.4 TB) and over 30,000 spectra (7 spectroscopic datasets). These data are the science products of: The Two Micron All Sky Survey (2MASS), The Infrared Astronomical Satellite (IRAS), The Midcourse Space Experiment (MSX), The Submillimeter Wave Astronomy Satellite (SWAS), The Infrared Space Observatory (ISO), The Infrared Telescope in Space (IRTS), The Spitzer First Look Survey (FLS), Spitzer Legacy & Ancillary data, Spitzer Reserved Observations (ROC) and the Spitzer Space Telescope data. IRSA is also seamlessly interoperable with ten remote archives and services: GOODS, ISO, MAST, VizieR, DSS, NVSS, FIRST, HEASARC, NED and JPL, which help expand the available dataset wavelength range from X-ray to radio. The majority of IRSA's image collections are Simple Image Access (SIA) compliant and are available through the Virtual Observatory (VO) data mining tools. The IRSA demo includes IRSA's ¯ve main services: inventory service RADAR, catalog query service Gator, data fusion service OASIS, general search service for complex data collections Atlas, and IRSA's 2MASS Image data access services. IRSA's website is http://irsa.ipac.caltech.edu

Band Merging of Spitzer Detections in the SWIRE Fields

The Spitzer Wide-area Infra-Red Extragalactic (SWIRE) Survey has imaged 49 deg^2 of high-Galactic-latitude sky in seven infrared bands spanning wavelengths from 3.6 μm to 160 μm, with beam sizes ranging from about 2″ to 40″. Lists of extracted sources from the individual bands are merged using the Spitzer band merging software. Positions and their uncertainties are used to identify possible band-to-band matches, then decision theory is applied to choose a best match. We present our assessment of band merging reliability based on analysis of the random match rate, and we discuss our application of constraints of multi-band detections and proximity to produce reliable catalogs. We examine the crucial role played by positional uncertainties for extractions made with SExtractor and with Spitzer's Astronomical Point-source EXtraction (APEX) software

Ten years of software sustainability at the Infrared Processing and Analysis Center

This paper presents a case study of an approach to sustainable software architecture that has been successfully applied over a period of 10 years to astronomy software services at the NASA Infrared Processing and Analysis Center (IPAC), Caltech (http://www.ipac.caltech.edu). The approach was developed in response to the need to build and maintain the NASA Infrared Science Archive (http://irsa.ipac.caltech.edu), NASA's archive node for infrared astronomy datasets. When the archive opened for business in 1999 serving only two datasets, it was understood that the holdings would grow rapidly in size and diversity, and consequently in the number of queries and volume of data download. It was also understood that platforms and browsers would be modernized, that user interfaces would need to be replaced and that new functionality outside of the scope of the original specifications would be needed. The changes in scientific functionality over time are largely driven by the archive user community, whose interests are represented by a formal user panel. The approach has been extended to support four more major astronomy archives, which today host data from more than 40 missions and projects, to support a complete modernization of a powerful and unique legacy astronomy application for co-adding survey data, and to support deployment of Montage, a powerful image mosaic engine for astronomy. The approach involves using a component-based architecture, designed from the outset to support sustainability, extensibility and portability. Although successful, the approach demands careful assessment of new and emerging technologies before adopting them, and attention to a disciplined approach to software engineering and maintenance. The paper concludes with a list of best practices for software sustainability that are based on 10 years of experience at IPAC