Ultraviolet to optical diffuse sky emission as seen by the Hubble Space Telescope Faint Object Spectrograph

Kimiaki Kawara, Yoshiki Matsuoka, Kei Sano, Timothy D. Brandt, Hiroaki Sameshima, Kohji Tsumura, Shinki Oyabu, Nobuyuki Ienaka

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


We present an analysis of the blank-sky spectra observed with the Faint Object Spectrograph on board the Hubble Space Telescope. We study the diffuse sky emission from ultraviolet to optical wavelengths, which is composed of zodiacal light (ZL), diffuse Galactic light (DGL), and residual emission. The observations were performed towards 54 fields distributed widely over the sky, with spectral coverage from 0.2 to 0.7 μm. In order to avoid contaminating light from earthshine, we use the data collected only in orbital nighttime. The observed intensity is decomposed into the ZL, DGL, and residual emission, in eight photometric bands spanning our spectral coverage. We found that the derived ZL reflectance spectrum is flat in the optical, which indicates major contribution of C-type asteroids to the interplanetary dust (IPD). In addition, the ZL reflectance spectrum has an absorption feature at ∼0.3 μm. The shape of the DGL spectrum is consistent with those found in earlier measurements and model predictions. While the residual emission contains a contribution from the extragalactic background light, we found that the spectral shape of the residual looks similar to the ZL spectrum. Moreover, its optical intensity is much higher than that measured from beyond the IPD cloud by Pioneer 10/11, and also than that of the integrated galaxy light. These findings may indicate the presence of an isotropic ZL component, which is missed in the conventional ZL models.

Original languageEnglish
Article number31
JournalPublications of the Astronomical Society of Japan
Issue number2
Publication statusPublished - 2017 Apr


  • Cosmic background radiation
  • Dust, extinction
  • Earth
  • Galaxies: evolution
  • Zodiacal dust

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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