page_title: Cygnus X-3
section_title: Observations
hierarchical_section_title: Cygnus X-3 / Observations
caption_attribution_description: English: Halo around the X-ray source Cygnus X-3. The halo (beyond the yellow ring in the center) is due to scattering of the x-rays by interstellar dust grains along the line of sight to the source. The sharp horizontal line is an instrumental effect.
context_page_description: Cygnus X-3 is a high-mass X-ray binary, one of the stronger binary X-ray sources in the sky. It is often considered to be a microquasar, and it is believed to be a compact object in a binary system which is pulling in a stream of gas from an ordinary star companion. It is the only known HMXB containing a Wolf-Rayet star. It is invisible visually, but can be observed at radio, infrared, X-ray, and gamma-ray wavelengths.
context_section_description: Cygnus X-3 is a prominent X-ray source, with soft and hard X-rays both varying in intensity.  Periods where the hard X-rays are at minimum intensity are known as soft states.  It is less than half a degree from a gamma-ray pulsar, but is itself a weak gamma-ray source. It also shows periodic gamma-ray flares, apparently all occurring during the soft state.
  It is undetectable at visual wavelengths due to extreme extinction in the galactic plane.  However, there is an infrared point source at its position.  Cygnus X-3 is also notable as the only microquasar firmly detected in the high energy gamma rays in the range >100 MeV.
  Because of the variations in emission at various wavelengths, Cygnus X-3 has been given the variable star designation V1521 Cygni.
caption: Cygnus X3 and its X-ray halo
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