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Downtime
STScI will be performing network upgrades on the following dates:
  • Sat 17 Apr 2021, 7:00 AM - 2:00 PM EDT (11:00 - 18:00 UTC)
  • Sat 24 Apr 2021, 7:00 AM - 4:00 PM EDT (11:00 - 20:00 UTC)
  • Sat 1 May 2021, 7:00 AM - 4:00 PM EDT (11:00 - 20:00 UTC)
  • Sun 2 May 2021, 7:00 AM - 4:00 PM EDT (11:00 - 20:00 UTC)
  • Sat 8 May 2021, TBD
  • Sun 9 May 2021, TBD
Services may be unavailable or interrupted during these times.

Active Galactic Nucleus Example Spectrum

NGC 4151
Click on the above spectrum to see it in its full glory. Note the spectrum shown is from old HUT data (pre-2013 version), but is still representative.

This ultraviolet spectrum of the active galaxy NGC 4151 obtained by HUT during the Astro-1 flight shows the intensity of light recorded by HUT's detector at each wavelength. Emission features and absorption features due to various ionization states of different elements in the hot gas present in the nucleus of this active galaxy are marked.

Want to know more about how astronomers analyze such spectra and actually learn about distant objects in the Universe? Check out the educational Web site: What are Those Squiggly Lines? Learning from Light, put together by HUT astronomer Bill Blair.