new database at IAP, with access tools slightly different from the MAST. The archive presently ... tutorial for new navigators and SQL beginners. 3. Database ...
Astronomical Data Analysis Software and Systems XV ASP Conference Series, Vol. 351, 2006 C. Gabriel, C. Arviset, D. Ponz and E. Solano, eds.
The IAP FUSE Database: a Virtual Observatory Interactive Web Tool ´ J.-M. D´esert, G. H´ebrard, A. Lecavelier des Etangs, R. Ferlet, A. Vidal-Madjar Institut d’Astrophysique de Paris, CNRS, 98 bis Boulevard Arago, F-75014 Paris, France I. Chilingarian CRAL Observatoire de Lyon, France; Sternberg Astronomical Institute, Russia Abstract. We have developped a database containing more than four thousands FUSE (Far-Ultraviolet Spectroscopic Explorer) public observations at IAP, Paris. FUSE is a NASA/CNES-supported astronomy mission that was launched on June 24, 1999, to explore the Universe using the technique of high-resolution spectroscopy in the far-ultraviolet spectral region (see http://fuse.pha.jhu.edu/). Up to now, more than four thousands FUSE public observations are available and the telescope is still observing. This database is an user friendly and interactive tool to sort out the data using various criteria, to cross correlate or apply real time calculations on the spectrum, in order to visualize and to retrieve datasets. To improve its capabilities, this database is linked to the MAST and the CDS and appear in the Vizier tool. We have developed this interactive web-accessed database to provide to the community an easy way to access the data (see http://fuse.iap.fr). This work was supported by the CNES (the French space agency) We have developed an SSAP (simple spectral access protocol) for this database in collaboration with others spectral databases in the fields of stars and galaxies. Now that we have registered this database in the NVO registry, the spectrum are accessible by everyone using any VO-compliant tools without knowing the database or the FUSE programme itself. Here we present how we have been able to simply convert our already existing UV spectral database into a VO object. We show how we connected this database within the VO, and present the set of tools that we have developed and which are accessible for the community to convert the FUSE fits data into VOTable format.
1.
Scientific Content of the Database
The FUSE archive is hosted by the Multi-mission Archive at the Space Telescope Science Institute (MAST). The data can be accessed from the MAST 475
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web page at: http://archive.stsci.edu/fuse. The pages and forms are self explanatory and anyone can access all engineering and scientific files (raw and calibrated). The spectrum have been reduced by the FUSE team project at JHU (Johns Hopkins University) who have developed a standard pipeline for this purpose. An agreement between NASA and CNES ensures that the MAST sends each month to IAP the new public data and all the associated files. Getting all those public datasets (raw and calibrated), we decided to developed a new database at IAP, with access tools slightly different from the MAST. The archive presently contains more than 3500 public datasets, so more than 50,000 calibrated spectra and their corresponding original two-dimensional images obtained in the interval 1999-2005. Even though it is complete, only data after the 6 months exclusivity period become available to the astronomical community. The scientific content of the database is very rich, since different kinds of objects have been observed with FUSE for different purposes in the FUV wavelength range of 90.5-118.7 nm, with a spectral resolution around 15000 and a signal-to-noise ratio from 3 to 30 depending of the observation. All FUSE data products are in standard FITS (Flexible Image Transport System) format with the data contained in binary extensions. Due to the optical design of the FUSE instrument, each exposure on a target produces independent SiC and LiF spectra for each detector segment (1 and 2) hence a total of 8 separate spectra (2 spectra (LiF+SIC) x 2 segments x 2 detectors). Data are recorded in histogram (HIST) or time-tagged (TTAG) modes, through the low(LWRS), medium- (MDRS), or high-resolution (HIRS) slit. Details of the FUSE instrument may be found in Moos et al. (2000) and Sahnow et al. (2000). In addition, the pipeline generates 3 co-added spectra (one for each aperture) for TTAG exposures and 1 co-added spectrum for HIST exposures. Finally, the pipeline produces a merged spectrum for each observation (i.e. a co-addition of all the exposures) called ALL spectra. The co-added spectra are provided only for overview or quick look purposes and should not be used for scientific analysis. We strongly recommend to shift and co-add spectra separately for each independent channels (SiC1, SiC2, LiF1, and LiF2) and for a given slit after correction for relative wavelength offsets between individual calibrated exposures (typically, a few FUSE pixels). This correction procedure slightly improves the spectral resolution and yields some averaging out of the fixed-pattern noise in the detector, acting as a random FP split procedure (H´ebrard et al. 2002, Kruk et al. 2002).
2.
The User Interface
We designed two interfaces which are available on the web, a fast access one and a SQL navigator accessible through the website: http://fuse.iap.fr 2.1.
The Quick and Easy Access Interface
The principal Web page of the database interface is written in PHP and is designed in a similar way as the MAST (Multimission Archive at STScI) archive Web page in order to facilitate its use by the customers of this database. Tar-
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gets can be searched using either object-naming conventions, positions or basic astronomical caracteristics such as the magnitude or the spectral type. The results of a search are then listed in the second dedicated Web page. Then the user can instantaneously download the archived calibrated scientific spectra. Finally, this interface allows to plot builds on-the-fly ALL spectra which have been reduced using the latest FUSE calibration pipeline CalFUSE available at that time. Not only the spectrum is accessible but also all available information about targets and observations. 2.2.
The SQL Access Interface
A more complete interface gives access to the whole database sending all kinds of request in SQL language. As the quick access interface, it allows neighbor searches, and cross correlations with other catalogues. This site provides a user’s specification query features as well as tooltips interface for all fields request. In order to help the user, we give a self-documentation of terms and tables, and a tutorial for new navigators and SQL beginners. 3.
Database Connections
The FUSE database is linked to the MAST. Targets are resolved using either the NED (NASA/IPAC Extragalactic Database) or Simbad Astronomical database operated at CDS (Centre de Donn´ees astronomiques de Strasbourg). Users can also access the FUSE database through requests from the Vizier Catalogue Service maintained by the CDS. This permits users to generate queries from other sites to cross-correlate, compare, and plot FUSE data using VO (Virtual Observatory) protocols through SSA protocol. Finally, the archive was developed under the current IVOA (International Virtual Observatory Alliance) standards of interoperability, allowing astronomers to access the spectrum with various VOtools already available to the worldwide community (like SpecView or VOSpec). Plans for future development in terms of improvements of spectral UV features, web services or on-line reduction, as well as data analysis, are currently studied. Our spectral manipulation program ”XIPLOT”, an IDL-based program developed by the French FUSE team, can be used to plot data and FITS, co-plot, shift and co-add FUSE exposures. This public tool is available at the French FUSE website. 4.
Scientific Issues
Various cross-correlations with other catalogues have been applied to the present database using the powerful tool Vizier from CDS, in order to mine scientific data or to prepare new proposals. As an example, more than one hundred detections of molecular lines from HD in the ISM have been found and catalogued in an automatic manner thanks to this database. This allows the French HD group to currently analyze a survey of this molecule throughout the disk (Lacour et al., 2005). Such a tool has been useful for the detection of the H− ion in the ISM with FUSE; it as also contributed to the detection of tiny-scale molecular structures in the Magellanic Clouds (Andr´e et al., 2004)
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Acknowledgments. Many thanks to Martin Lemoine for his useful comments. If the IAP FUSE database was helpful for your research work, the following acknowledgment would be appreciated: This research has made use of the FUSE database, operated at IAP, Paris, France. References Andr´e, et al., A&A, v.422, 483-504 (2004) H´ebrard, G., et al 2002, ApJS, 140, 103-114 Kruk, J. W., et al. 2002, ApJS, 140, 19 Lacour, S., et al. A&A, v.430, p.967-977 (2005) Moos, H. W., et al. 2000, ApJ, 538, L1 Sahnow, D. J., et al. 2000, ApJ, 538, L7
