4.2. Other Ultraviolet Satellites

4.2.1. International Ultraviolet Explorer (IUE)

The International Ultraviolet Explorer (IUE) launched on January 26, 1978 had an extremely successful 18+ years of operations. Its detectors could obtain spectra from 1150Å to 3200Å. The telescope consisted of an f/15 45cm beryllium mirror. The spectrographs obtained data in a low- or high resolution mode (6 and 0.1 Å respectively). At high resolution it was capable of observing sources up to 12mag, while at low resolution the limiting magnitude was 17. Some characteristics of the spectrographs are shown in Table 4.

Spectra obtained with IUE consist of a 1-D file with 768 pixels. All reduced images contain a photometrically corrected image file and an extracted spectrum file. All short (SWP) and long (LWP) wavelength data has been reprocessed. The Space Telescope Science Institute is the repository of IUE's final archive. Retrievals can be made at http://archive.stsci.edu/iue. European users might prefer to use the Spanish IUE node at http://www.vilspa.esa.es/iue.

4.2.3 Extreme Ultraviolet Explorer

The Extreme Ultraviolet Explorer (EUVE) was launched on June 7, 1992. The satellite has 5 instruments: four photometric imaging systems and a three-channel EUV spectrometer capable of obtaining astronomical observations between 70 and 760Å.

During the first phase of the mission a four-band (at 100Å, 200Å, 400Å and 600Å) sky survey in the extreme ultraviolet and a long exposure "deep survey" were conducted. The catalogs and lists resulting from this survey are published in Malina et al. (1994) and Bowyer et al. (1996), and include 400 EUVE sources.

During the on-going second part of the mission a Guest Observer (GO) program consisting of pointed spectroscopic observations is carried out.

Each detector has an area of 72.44 cm²; other characteristics of the EUVE spectrometers used in the GO phase are shown in Table 5.

After the proprietary period expired (usually 1 year after the observations were made), the data are available through ADS and the EUVE public data archive. The data are distributed as a set of FITS files and tables. Its content is described in the EUVE GO Handbook available on-line at CEA (http://www.cea.berkeley.edu)

The CEA now maintains a dedicated ADS node to provide sky survey data, EUVE calibration data, and pointed observations.

The on-line data available consist of:

• Surveys
1. sky maps from the survey observations made with the scanners
2. deep survey sky maps
3. catalogs of EUV sources
• GO data:
1. raw data in 3-D FITS tables
2. binned FITS images
3. 1-d extracted spectra
4. 1-d extracted spectra for calibration sources

A list of the pointed observations can be found at http://www.cea.berkeley.edu/~science/data/dynamic/exposures.html

A very handy Spectral Data Browser (http://www.cea.berkeley.edu/cgi-bin/archive_select) allows the user to select and retrieve public data directly from the WWW. The selection can be done by spectral type or by position.

Data is also periodically released on CD-ROM. The issued volumes include:

• Volume 1.1: all sky survey images and pointed spectroscopic calibration observation data for AT Mic.
• Volume 2.1A: pointed spectroscopic observations of 4 white Dwarfs (WD1845+019, Feige 24, G191-B2B and WD0549+158)
• Volume 2.1B pointed spectroscopic observations of late stars (Capella and Procyon)
• Volume 2.1C pointed spectroscopic observations of the white dwarf WD1620-391, the cataclysmic variable RE1938-461, the BL-Lac object PKS2155-304, the late type star HR1099 and the Moon
• Volume 2.2A pointed spectroscopic observations of three white dwarfs (WD2309+105, WD1254+223 and HZ43)
• Volume 2.2B pointed spectroscopic observations of three late-type stars ( Gem, AD Leo and Cen A)
• Volume 2.2C pointed spectroscopic observations of the B star CMa, the cataclysmic variable AN UMa and the planet Jupiter.

4.2.6. Astro Missions

The two Astro missions flew on board of the space shuttle and consisted of spectrographs, photometers and ultraviolet cameras. Astro-1 lasted 9 days in December 1990 and Astro-2 16 days in March 1995.

The instruments on board the Astro missions were:

BBXRT (Broad Band X-Ray Telescope) produced spectra between 0.3 and 10keV with a resolution of 90-200eV FWHM of around 80 sources during the Astro-1 mission

HUT (Hopkins Ultraviolet Telescope) produced spectra in the far UV (912Å-1850Å) with a 3Å resolution and in the extreme UV (415Å-912Å) with a resolution of 1.5Å for more than 300 sources

UIT (Ultraviolet Imaging Telescope) was a 38cm f/9 Ritchie-Chrétien telescope with two selectable cameras with a wavelength range between 1150Å and 3500Å. UIT included a set of Near and Far UV filters. The images were obtained on 70mm film that was scanned with different pixel sizes.

WUPPE (Wisconsin Ultraviolet Photopolarimeter Experiment) obtained simultaneous spectra and polarization measurement of 329 sources between 1400Å and 3200Å. The limiting magnitudes for these sources were between 0 and 8mag. WUPPE produced images in three sizes:

• field : 320 x 256pix (3.3' x 4.4'), 1-bit for identification and acquisition.
• zoom : 30 x 40pix (24" x 32") for fine pointing and focus.
• downfield : 320 x 256pix (3.3' x 4.4'), 6-bit for detailed images.

4.2.7. Astro Data

The data produced during the two missions is accessible through the Multimission Archive at STScI at http://archive.stsci.edu/mast.html. The Web Interface for Searching Archival Research Data (WISARD) provides a way to retrieve archival data located in different archival sites. WISARD can be found at http://hypatia.gsfc.nasa.gov/wisard/wisard.html.

4.2.8 Far Ultraviolet Spectroscopic Explorer (FUSE)

FUSE (http://fuse.pha.jhu.edu) to be launched in 1999 will obtain high resolution between 905Å and 1195Å. It contains four slits:

• high resolution aperture (1.25" x 20").
• high throughput aperture (4" x 20").
• large square aperture (30" x 30").
• pinhole aperture (~ 0.5").

The FUSE spectra will complement those obtained by HST as they are further in the UV.