Question: What is is a concave golden disc of a weight of 25.23 g and a diameter of 4.5 cm, that had a king of Denmark and Norway was mentioned in the inscription of the disc?

full_context: Document 1: Harald Bluetooth: Harald "Bluetooth" Gormsson (Old Norse: "Haraldr Gormsson" , Danish: "Harald Blåtand Gormsen" , died c. 985/86) was a king of Denmark and Norway.
Document 2: Strut-Harald: Strut-Harald ("Cone Harald" from his cone-shaped helmet of gold) was a semi-legendary jarl or petty king who ruled over the Danish territory of Scania (in what is now southern Sweden) during the late 10th century CE (approximately 975-986). Norse sagas identify him as the son of Gorm the Old, His Sister being Astrid Wiffen who was married to the Earl Philippus Sigefrid Wiffen of Scania, Strut-Harald was also a half-brother of Harald Bluetooth.
Document 3: Halfdan Haraldsson the Black: Halfdan Haraldsson or Halfdan the Black (not to be confused with his grandfather and namesake) was a son of Harald I of Norway by his first wife, Åsa, the daughter of Jarl Håkon Grjotgardsson of Lade. He was made sub-king of the Trondelag by his father, along with his brother Halfdan the White. According to "Heimskringla", Halfdan the Black was poisoned, possibly at the behest of his sister in law Gunnhild, Mother of Kings.
Document 4: Chiemsee Cauldron: The Chiemsee Cauldron is a gold cauldron found at the bottom of Lake Chiemsee in Bavaria in 2001. The cauldron is decorated with figures reminiscent of the style of the Gundestrup cauldron. It has a diameter of 50 cm and a height of 30 cm, and is made from 10.5 kg (23.15 pounds) of 18 carat gold.
Document 5: The Story of Sigurd the Volsung and the Fall of the Niblungs: The Story of Sigurd the Volsung and the Fall of the Niblungs
Document 6: Halfdan the Black: Halfdan the Black (Old Norse: "Halfdanr Svarti") (  810 –  860 ) was a ninth-century king of Vestfold. He belonged to the House of Yngling and was the father of Harald Fairhair, the first king of Norway.
Document 7: House of Knýtlinga: The Danish House of Knýtlinga (English: "House of Cnut's Descendants") was a ruling royal house in Middle Age Scandinavia and England. Its most famous king was Cnut the Great, who gave his name to this dynasty. Other notable members were Cnut's father Sweyn Forkbeard, grandfather Harald Bluetooth, and sons Harthacnut, Harold Harefoot, and Svein Knutsson. It has also been called the House of Canute, the House of Denmark, the House of Gorm, or the Jelling Dynasty.
Document 8: Ragnvald Heidumhære: Ragnvald Heidumhære (or Rognvald) was a legendary, possibly historic, petty king or chieftain of Vestfold in what is today Norway in the 9th century, according to "Ynglingatal" and to "Ynglinga saga" in "Heimskringla". He was the son of Ragnar Lodbrok or Olaf Geirstad-Alf. His name "Heiðumhæri" could be translated as "highly honoured"
Document 9: Hammer of Thor (monument): The Hammer of Thor is a 3.3 m tall, t-shaped, man-made rock formation, located along the Arnaud River in the Ungava Peninsula, Quebec, Canada. It was discovered in 1964 by an archaeologist who thought it was erected by Vikings. He named it "The Hammer of Thor", in reference to the hammer-wielding Thor of Norse culture. Today some scholars believe that it is more likely to be an artifact of Inuit culture, an inuksuk or stone landmark.
Document 10: Gundestrup cauldron: The Gundestrup cauldron is a richly decorated silver vessel, thought to date from between 200 BC and 300 AD, or more narrowly between 150 BC and 1 BC. This places it within the late La Tène period or early Roman Iron Age. The cauldron is the largest known example of European Iron Age silver work (diameter: 69 cm ; height: 42 cm ). It was found dismantled, with the other pieces stacked inside the base, in 1891 in a peat bog near the hamlet of Gundestrup in the Aars parish of Himmerland, Denmark ( ). It is now usually on display in the National Museum of Denmark in Copenhagen, with replicas at other museums; during 2015-16 it was in the UK on a travelling exhibition called "The Celts".
Document 11: Curmsun Disc: Curmsun Disc is a concave golden disc of a weight of 25.23 g and a diameter of 4.5 cm . The Danish Viking king, Harald Bluetooth, is mentioned in the inscription of the disc.
Document 12: Harald V of Norway: Harald V (] ; born 21 February 1937) is the King of Norway, having ascended the throne following the death of his father on 17 January 1991.
Document 13: Gryting, King of Orkdal: Gryting was according to Heimskringla a king of Orkdal in the period leading up to Harald Fairhair's unification of Norway. He was the first leader in Trøndelag to make a stand against King Harald's ravaging of the country. At the battle of Orkdal Gryting's men were defeated and Gryting taken prisoner. After this Gryting swore allegiance to king Harald.
Document 14: Svinfylking: The Svinfylking, Old Norse for 'Swine Array' or 'Boar Snout', was a version of the wedge formation used in Iron Age Scandinavia then by the Vikings, and by the Germanic peoples during the Germanic Iron Age where it was known as the "Schweinskopf" or 'Swine's Head'. Its invention was attributed to the god Odin.
Document 15: Sigtryg Eysteinsson: Sigtryg Eysteinsson was king of the Norwegian petty kingdoms Raumarike and Hedmark in what is today south-eastern Norway. He was killed by Halfdan the Black ("Halvdan Svarte") in the middle of the 9th century. Halfdan the Black subdued the area by first defeating and killing Sigtryg in battle and then defeated Sigtryg's brother and successor Eystein Eysteinsson in a series of battles.
ground_truth: Curmsun Disc