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Observational instruments

The Sun is under constant observation by a variety of spacecraft and ground based instruments. The data collected by these instruments is central to our improved understanding of solar physics. Instruments currently in operation include:

  • Hinode - meaning "sunrise" in Japanese, the Hinode satellite was launched in September 2006, making it one of the most recent additions to the solar observation network. It features a Solar Optical Telescope (SOT) with 0.2 arcsecond resolution, an X-ray telescope (XRT), and an EUV Imaging Spectrometer (EIS) more sensitive than its predecessor on board SOHO.
  • STEREO - The Solar Terrestrial Relations Observatory was launched in October 2006 and consists of two almost identical satellites; one ahead of the Earth's orbit, and one an equal distance behind. One of the main purposes of STEREO is to observe CMEs from multiple viewing angles. The two satellites each house a variety of instruments including white-light coronographs, a heliospheric imager (HI), as well as instruments for solar wind and plasma characteristic measurements.
  • RHESSI - The Reuven Ramaty High Energy Spectroscopic Imager has been in operation since 2002, and sits in a low orbit around the Earth. RHESSI's primary purpose is to study the energy releases associated with solar flares and the solar corona in general. The instrument consists of nine photometric detectors with sets of collimating grids mounted in front, and can be used for both imaging (where it uses collimating optics) and spectroscopy. RHESSI is capable of observing a wide energy range, from thermal energies (~ 6 keV) to gamma rays.
  • TRACE - The Transition Region and Coronal Explorer is a NASA small explorer mission and can generate high resolution images of the solar corona, transition region and photosphere. TRACE was launched in April 1998 and has been observing in EUV and UV wavelengths since then.
  • SOHO - The Solar and Heliospheric Observatory was an ESA and NASA collaboration and was launched in 1995, making it one of the older satellites currently in operation. SOHO orbits the Sun in the Sun-Earth line, where it sits at the Lagrangian (L1) point, approximately 1.5 million kilometers away from Earth. This allows for uninterrupted observations of ths Sun. SOHO houses 12 different instruments, including an Extreme Ultraviolet Imaging Telescope (EIT), a Coronal Diagnostic Spectrometer (CDS), and a Michelson Doppler Imager (MDI).
  • Ulysses - The Ulysses spacecraft was launched in October 1990. Unlike most other solar satellites, Ulysses was designed to fly out of the plane of the solar system and orbit the sun at high inclination in order to observe the solar poles. Ulysses made its first orbital pass in 1994/95, and began its third northern pole pass in November 2007. Ulysses houses a variety of instruments that primarily study the solar wind speed and magnetic field strength. Due to dwindling power reserves on board the spacecraft, Ulysses operations are currently winding down as of January 2008.
  • Nobeyama Radioheliograph - The Nobeyama Radioheliograph is a ground-based interferometer located in Japan, consisting of 84 parabolic antennas situated in north/south and east/west lines. It was completed in 1992 and has been making daily observations of the Sun at radio wavelengths since then. The Radioheliograph observes at the dual frequencies of 17 GHz and 34 GHz and has a spatial resolution of up to 5 arcseconds at 34 GHz. It is also capable of imaging frames at a rate of 0.1s.
  • Big Bear Solar Observatory - The Big Bear Solar Observatory was built in 1969 in the middle of Big Bear Lake in California. It contains several telescopes, including a full disk H-alpha telescope. A 1.6m New Solar Telescope (NST) is currently under construction and should be completed in 2008.