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Astronomical Data Analysis Software and Systems VI ASP Conference Series, Vol. 125, 1997 Gareth Hunt and H. E. Payne, eds.

Design and Implementation of CIA, the ISOCAM Interactive Analysis System
S. Ott,1 A. Ab ergel,2 B. Altieri,1 J-L. Augueres,3 H. Aussel,3 J-P. Bernard,2 A. Biviano,1,4 J. Blommaert,1 O. Boulade,3 F. Boulanger,2 C. Cesarsky,5 D. A. Cesarsky,2 A. Claret,3 C. Delattre,3 M. Delaney,1,6 T. Deschamps,3 F-X. Desert,2 P. Didelon,3 D. Elbaz,3 P. Gallais,1,3 R. Gastaud,3 S. Guest,1,7 G. Helou,8 M. Kong,8 F. Lacomb e,9 J. Li,8 D. Landriu,3 L. Metcalfe,1 K. Okumura,1 M. Perault,2 A. M. T. Pollock,1 D. Rouan,9 J. Sam-Lone,3 M. Sauvage,3 R. Sieb enmorgen,1 J-L. Starck,3 D. Tran,3 D. Van Buren,7 L. Vigroux,3 and F. Vivares2 1 ISO Science Operations Centre, Astrophysics Division of ESA, Vil lafranca del Castil lo, Spain
2 3 4 5 6 7 8 9

IAS, CNRS, University of Paris Sud, Orsay, France CEA, DSM/DAPNIA, CE-Saclay, Gif-sur-Yvette, France Istituto TESRE, CNR, Bologna, Italy CEA, DSM, CE-Saclay, Gif-sur-Yvette, France UCD, Belfield, Dublin, Ireland RAL, Chilton, Didcot, Oxon, England IPAC, JPL and Caltech, Pasadena, CA, USA DESPA, Observatoire de Paris, Meudon, France

Abstract. This pap er presents an overview of the Interactive Analysis System for ISOCAM (CIA).1 With this system ISOCAM data can b e analysed for calibration and engineering purp oses, the ISOCAM pip eline software validated and refined, and astronomical data processing can b e p erformed. The system is mainly IDL-based but contains fortran, C, and C++ parts for sp ecial tasks. It represents an effort of 15 manyears and is comprised of over 1000 IDL and 200 fortran, C, and C++ modules.

1

CIA is a joint development by the ESA Astrophysics Division and the ISOCAM Consortium led by the ISOCAM PI, C. Cesarsky, Direction des Sciences de la Matiere, C.E.A., France.

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© Copyright 1997 Astronomical Society of the Pacific. All rights reserved.


CIA, the ISOCAM Interactive Analysis System 1. Introduction

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ESA's Infrared Space Observatory (ISO ) was successfully launched on Novemb er 17th, 1995.2 ISO is a three-axis-stabilised satellite with a 60-cm diameter primary mirror (Kessler et al. 1996; Maldari et al. 1996). Its four instruments (a camera, ISOCAM, an imaging photo-p olarimeter, and two sp ectrometers) op erate at wavelengths 2.5­240 µm at temp eratures of 2­8 K. ISOCAM takes images of the sky in the wavelength range 2.5­18 µm (Cesarsky et al. 1996). It features two indep endent 32в32 pixel detectors: the shortwavelength channel (2.5­5.5 µm), and the long-wavelength channel (4­18 µm). A multitude of filters and lenses enable the observer to p erform measurements at different wavelengths, with different fields of view or p olarizers. 2. Requirements and Constraints

The requirements on CIA were, in decreasing order of imp ortance: 1. to calibrate ISOCAM, 2. to p erform fast data reduction to assess the ISOCAM p erformance during the Performance Verification phase of ISO, 3. to monitor the health of ISOCAM, 4. to provide the means to p erform any sort of investigation requested for problem diagnostics, 5. to assess the quality of ISOCAM pip eline data products, 6. to debug, validate and refine the ISOCAM pip eline, and 7. to p erform astronomical data-processing of ISOCAM data. External constraints were the extremely tight schedule (see §4) and the op erating system. For historical reasons, VAX/VMS was chosen as op erating system for the pip eline. It was also decided that data files within the processing environment b e in a VAX-sp ecific variant of FITS. Therefore, in order to stay as close as p ossible to the ISOCAM pip eline, the op erational CIA version had to run under VMS. To achieve sufficient p erformance, it was decided to opt for VMS/Alpha instead of a classical VAX op erating system, and accept the minor p orting efforts required. 3. Design and Evolution

Given the time constraints and the team-structure, it was decided to re-use the existing IDL exp erience and code as much as p ossible. Therefore IDL (V3.6)
2

ISO is an ESA pro ject with instruments funded by ESA member states (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.


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Ott et al.

and high level languages (C, C++) for sp ecial IA applications and fortran (programming language for the pip eline) were chosen. In order to b e able to meet the schedule, it was decided to break the development down into three steps: a mimimum system, covering requirements 1­4; an op erational system, covering requirements 1­6; and the final astronomical data-processing system, covering all requirements listed in the previous section. The core system was intended for exp ert users, having only a very limited use of graphical user interfaces for display purp oses. Standardized module headers were designed to provide help to the users. Their contents feed into · a document generator to create a user's reference and a programmer's reference manual, · a comfortable, widget-based help-browser, using also the hierarchical organisation of the modules, to guide users, and · the standard IDL help widgets. For the full astronomical data-processing system, a UNIX version tuned to the needs of astronomers was introduced, together with more user-friendly, widget-based applications. 4. Schedule and Cost

The development of CIA b egan in June 1994 and followed standard software engineering practice (ESA PSS-05). User requirements were consolidated in Septemb er 1994 and the first version of the architectural design document agreed in Novemb er 1994. The minimum system was completed to meet the target date for IA readiness in April 1995, and the op erational system in Novemb er 1995 prior to the launch of ISO. Since then, work has continued for the astronomical data-processing system, the next version is exp ected to b e released in Decemb er 1996. Currently, the system is comprised of over 1000 IDL modules totalling over 210,000 lines, around 200 fortran files taken from the pip eline processing system, and around 10 fortran, C, and C++ files for sp ecialized (mainly cpuintensive) applications. Around 15 man-years have b een sp ent in the development of the IA core system, excluding the time for algorithmic research. For comparison, 30 manyears went into the calibration of ISOCAM and 5 man-years into ISOCAM related pip eline processing. This amounts to around 3% of the overall cost of ISO Science op erations or 0.4% of the total ISO cost to completion. 5. Architecture and Design

A quasi-ob ject-oriented approach was taken, with functions communicating via standardized data structures. The same data structures are used by the pip eline, calibration procedures, and astronomical data analysis. This commonality improves considerably the sp eed of algorithmic development within CIA.


CIA, the ISOCAM Interactive Analysis System

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Raw Data (FITS)
Data Preparation

SCDs
Calibration

CDS

B a s i c

A n a l y s i s

Freeze

PDS

R e f i n e d

A n a l y s i s

SADs

AAR Final Products (FITS)
Figure 1. Data Flow and Architecture.

SCDs (Science CAM Data) are self-contained entities, holding al l data of an ISOCAM state.3 They are generic, i.e., indep endent from the observation mode and can b e re-arranged to suit all needs. CDSs (Calibration Data Set) are self-contained entities, holding the calibration results. They are used directly within CIA, or transformed into calibration files, accessed by the pip eline. SADs (Science Analysed Data) are similar to SCDs, but hold the results either from Auto Analysis (AAR), or following an analysis by Interactive Analysis. SCDs, CDSs and SADs are implemented as complex IDL data structures using p ointers and therefore need dedicated access functions. PDSs (Prepared Data Structures) are self-contained entities, holding the data currently recognized as relevant for data reduction and their result for an ISOCAM observation. Their flavour dep ends on their purp ose, determined by the ISOCAM observation mode. PDSs are implemented as IDL structures. References Cesarsky, C., et al. 1996, A&A, 315, 32 Delaney, M. ed., ISOCAM Interactive Analysis User's Manual, ESA Document ESA Software Engineering Standards, ESA Document, Reference PSS-05 Kessler, M., et al. 1996, A&A, 315, 27 Maldari, P., Riedinger, J., & Estaria, P. 1996, ESA Bulletin, numb er 86 Sieb enmorgen, R., et al. ISOCAM Data User's Manual, ESA Document, Reference SAI/95-221/DC

3

A state is the atomic unit of CAM activities. An ISO pointing and all CAM parameters are fixed within a state.