Space Telescope European Coordinating Facility Research Articles

The Hubble Legacy Archive NICMOS grism data

The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope - European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes. In this paper, we present the HLA NICMOS G141 grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available through a web form at this http URL and via VO interfaces. In total, 2470 spectra of 1923 unique targets are included in the current release.

The Deep Lamp Project: An Investigation of the Precision and Accuracy of the Echelle Wavelength Scales of Space Telescope Imaging Spectrograph

The precision and absolute accuracy of the echelle mode wavelength scales of Space Telescope Imaging Spectrograph (STIS) are investigated. The method is to measure deep exposures of the onboard Pt/Cr-Ne hollow cathode calibration lamp. The standard deviation of emission spots from their laboratory wavelengths in a single image is a measure of the internal precision of the pipeline-assigned scales. The average shift of the image as a whole is a measure of the absolute accuracy. While systematic patterns can be identified in all four echelle modes (E140M, E140M, E230M, and E230H), the overall precision (even without compensating for long-range trends with λ) is excellent: of order one-tenth of the resolution element (σ ~ 600 and 300 m s−1, for medium- [M] and high- [H] resolution modes, respectively). Furthermore, the absolute accuracy and its repeatability (assessed in a time series of WAVECAL images) is of order a remarkable 100 m s−1, aside from one of the E230M modes (secondary tilt λ2269) that shows a systematic offset 10 times larger. The excellent precision of the STIS echelle wavelengths could be improved by adding higher order terms to the biquadratic polynomial currently implemented in the CALSTIS pipeline. On the other hand, the existing small distortions might be resolved more naturally by a physical instrument model, currently under development by the Space Telescope European Coordinating Facility's STIS Calibration Enhancement Project.

Scientific Research using the Electronic Archive of the Hubble Space Telescope

The Hubble Space Telescope (HST), a collaborative project between the US National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) has been operating since 1990. The European HST Science Data Archive, operated at the Space Telescope European Coordinating Facility(ST-ECF) in Garching, Germany, contains all data taken with the scienceinstruments of the HST. The services of the Archive include data browsing,preview, retrieval and re-calibration. Access to the Archive is providedthrough the World Wide Web, data distribution is through the Internet oron bulk media.This paper describes the data products, access to theArchive services, and the procedures for the use of the HST Science DataArchive by qualified scientists from remote locations. The Archive providestools implemented as Java Applets which can be used over the Net. For moresophisticated operations access to a suitable data analysis system isrequired; such software can be downloaded from our site.

Utilization of the European Hubble Space Telescope Science Data archive

The Hubble Space Telescope (HST) is a very complex astronomical observing facility, producing data with unique calibration and analysis requirements. The data are collected in Science Data Archives which are available through computer networks world wide. This paper describes the approaches and technologies which are being used at the Space Telescope European Coordinating Facility (ST-ECF) to enable users in different institutions to efficiently work with HST data.

The European HST science data archive

The design of the Data Management Facility (DMF), the system to handle the data from HST, has been based on the concepts of modularity and flexibility, so that changes inevitably due to occur during the long lifetime of the project could be gracefully accomodated. At the Space Telescope European Coordinating Facility (ST-ECF), new constraints have led the archive group to evolve the system, so to allow a more efficient ingesting of the data imported from the Space Telescope Science Institute (STScI), an easier browsing of the HST catalogue of observations, and a more efficient servicing of archive researchers' retrieval requests. In this paper, the European Science Data Archive of HST data is described, with particular reference to dataflow, hardware and software system structure, operations, differences with DMF, and foreseen developments.