Hercules-Corona Borealis Great Wall or the Great GRB Wall is the largest known structure in the observable universe, measuring 10 billion light years in length. This massive superstructure is a region of the sky seen in the data set mapping of gamma-ray burst that has been found to have an unusually higher concentration of similarly distanced GRBs than expected average distribution.
It was discovered in early November 2013 byt a team of American and Hungarian astronomers led by Istvan Horvath, Jon Hakkila and Zsolt Bagoly whyle analizing data from the Swift Gamma-Ray Burst Mission, together with the other data from ground-based telescopes.
It is the largest known formation in the universe, exceeding the size of the prior Huge-LQG by about two times.
The over density lies at the Second, Third and Fourth Galactic Quadrants (NQ2, NQ3 and NQ4 ) of the sky.
Thus, it lies in the Northen Hemisphere, centered on the border id the constellation Draco and Hercules. The entire clustering consists of around 19 GRBs with the redshift ranges between 1.6 and 2.1.
The authors of the paper concluded a structure that was the possible explanation of the clustering, but they never associated any name with it. Hakkila stated that:
“During the process, we were more concerned with whether it was real or not.”
The term “Hercules-Corona Borealis Great Wall” was coined by a Filipino teenager from Marikina City after reading a Discovery News report three weeks after the structure’s discovery in 2013.
The nomenclature was used by Jacqueline Howard, on her “Talk Nerdy to Me” video series, and Hakkila would later use the name.
The term is misleading, since the clustering occupies a region much larger than the constellations Hercules and Corona Borealis. In fact, it covers the region from Bootes to as far as the Zodiac constellation Gemini. In addition, the clustering is somewhat roundish in shape, which is more likely a supercluster, in contrast to an elongated shape of a galaxy wall. Another name, Great GRB Wall, was proposed in a later paper.