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The IUE ASCII LOGS are a set of observing logs for the International UltravioletExplorer (IUE). The series of IUE ASCII Logs contain summaries of IUE observations obtained from the IUE database. A log of all IUE observations excluding the solar system was created. In addition to a file containing the solar system objects, other files containing like groups of objects were created based on the IUE object classification assignment.

LogObject ClassesSort
    Uncompressed (12.8 Mbytes)
    GZIP Compressed (2.3 Mbytes)
10 - 97coordinates
Solar System
    Uncompressed(1.0 Mbytes)
    GZIP compressed(192 kbytes)
1 - 8 object class, object name
    Uncompressed(11.2 Mbytes)
    GZIP compressed(1.9 Mbytes)
10 - 66coordinates (J2000)
    Uncompressed(603 kbytes)
    GZIP compressed(122 kbytes)
69 - 76 coordinates (J2000)
    Uncompressed(1.1 Mbytes)
    GZIP compressed(221 kbytes)
80 - 90 coordinates (J2000)
    Uncompressed(751 kbytes)
    GZIP compressed(113 kbytes)
98 - 99 object class, coordinates

The fields contained in the logs are listed below.

object_name target name assigned by the original Guest Observer
ra,decRA and Dec of target (J2000)
observation date date and time of observation start
image_id image identifier includes the camera name and image number
dispersion dispersion used (H=high; L=low)
aperture aperture used (L = Large; S=small)
object class IUE object class (assigned by the original Guest Observer)
effective exposure length effective integration time in seconds. This time has been corrected for camera rise time and camera exposure quantization for most exposures, and aperture length and trail rate quantization for trailed exposures.
program id program id of the observing program for which the data were acquired
exposure mode Exposure mode. Three characters (XXX) are given to indicate whether the exposure was trailed, multiple, or segmented, in that order.
Trailed values
  • X --> trailed along FES X-axis
  • Y --> trailed along FES Y-axis
  • N --> Not trailed

  • Multiple values
  • X --> spectra offset along FES X-axis
  • Y --> spectra offset along FES Y-axis
  • A --> spectra offset along Aperture
  • O --> spectra offset is nonstandard
  • N --> not multiple

  • Segmented values
  • Y --> Yes segmented
  • N --> Not segmented
  • Comments GSFC observations will typically have format E=126,C=125,B=66 where
  • E is gross exposure level in DN for strongest emission line;
  • C is gross DN value for the most highly exposued region of the continuum;
  • B is the average DN value for the background (usually near the maximum continuum);
  • N is the peak DN value for the microphonic noise.

  • VILSPA observations typically have format starting with three digit number (e.g.) 702 CENTER OF LIGHT where the
  • digit 1 = exposure level of the continuum
  • digit 2 = exposure level of the emission lines
  • digit 3 = background level
  • and values are:
  • 0: not applicable
  • 1: no spectrum visible
  • 2: faint spectrum: max DN < 20 above local background
  • 3: underexposed: max DN < 100 above local background
  • 4: weak: max DN between 100 and 150 above local background
  • 5: good: no saturation but max DN over 150 above local background
  • 6: a bit strong: a few pixels saturated
  • 7: saturated for less than half the spectrum
  • 8: mostly saturated but some parts usable
  • 9: completely saturated