Like a recording artist who has had a long career, NASA's Chandra X-ray Observatory has a "back catalog" of cosmic recordings that is impossible to replicate. To access these X-ray tracks, or observations, the ultimate compendium has been developed: the Chandra Source Catalog (CSC).
The CSC contains the X-ray data detected up to the end of 2020 by Chandra, the world's premier X-ray telescope and one of NASA's "Great Observatories." The latest version of the CSC, known as CSC 2.1, contains over 400,000 unique compact and extended sources and over 1.3 million individual detections in X-ray light.
Before and After
X-ray Images of Sagittarius A*
1999 - 2021
Within the CSC, there is a wealth of information gleaned from the Chandra observations - from precise positions on the sky to information about the the X-ray energies detected. This allows scientists using other telescopes - both on the ground and in space including NASA's James Webb and Hubble Space Telescopes - to combine this unique X-ray data with information from other types of light.
The richness of the Chandra Source Catalog is illustrated in a new image of the Galactic Center, the region around the supermassive black hole at the center of the Milky Way galaxy called Sagittarius A*. In this image that spans just about 60 light-years across, a veritable pinprick on the entire sky, Chandra has detected over 3,300 individual sources that emit X-rays. This image is the sum of 86 observations added together, representing over three million seconds of Chandra observing time.
Another new representation of the vast scope of the Chanda Source Catalog is found in a just-released sonification, the translation of astronomical data into sound. This sonification encompasses the new map that includes 22 years of Chandra observations across the sky, beginning from its launch through its observations in 2021. Because many X-ray sources have been observed multiple times over the life of the Chandra mission, this sonification represents those repeat X-ray sightings over time through different notes.
In the view of the sky, projected in a similar way to how the Earth is often depicted in world maps, the core of the Milky Way is in the center and the Galactic plane is horizontal across the middle of the image. A circle appears at the position of each detection and the size of the circle is determined by the number of detections in that location over time. A year counter appears at the top of the frame. Since Chandra continues to be fully operational, the text changes to "… and beyond" after 2021 as the telescope continues to collect observations. During the video, a collage of images produced by Chandra fades in as a background. In the final frames of the video, thumbnail images representing the thousands of Chandra observations taken over the lifetime of the mission appear behind the sky map.
The most recent version of the Chandra Source Catalog can be accessed at https://cxc.cfa.harvard.edu/csc/
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
