SN 1006

Historic reports

Egyptian astrologer and astronomer Ali ibn Ridwan, writing in a commentary on Ptolemy's Tetrabiblos, stated that the "spectacle was a large circular body, 21⁄2 to 3 times as large as Venus. The sky was shining because of its light. The intensity of its light was a little more than a quarter that of Moon light" (or perhaps "than the light of the Moon when one-quarter illuminated"). Like all other observers, Ali ibn Ridwan noted that the new star was low on the southern horizon. Some astrologers interpreted the event as a portent of plague and famine.

The most northerly sighting is recorded in the Annales Sangallenses maiores of the Abbey of Saint Gall in Switzerland, at a latitude of 47.5° north. Monks at St. Gall provided independent data as to its magnitude and location in the sky, writing that

[i]n a wonderful manner this was sometimes contracted, sometimes diffused, and moreover sometimes extinguished ... It was seen likewise for three months in the inmost limits of the south, beyond all the constellations which are seen in the sky.

This description is often taken as probable evidence that the supernova was of type Ia.

In The Book of Healing, Iranian philosopher Ibn Sina reported observing this supernova from northeastern Iran. He reported it as a transient celestial object which was stationary and/or tail-less (a star among the stars), that it remained for close to 3 months getting fainter and fainter until it disappeared, that it threw out sparks, that is, it was scintillating and very bright, and that the color changed with time.

Some sources state that the star was bright enough to cast shadows; it was certainly seen during daylight hours for some time.

According to Songshi, the official history of the Song dynasty (sections 56 and 461), the star seen on May 1, 1006, appeared to the south of constellation Di, between Lupus and Centaurus. It shone so brightly that objects on the ground could be seen at night.

By December, it was again sighted in the constellation Di. The Chinese astrologer Zhou Keming, who was on his return to Kaifeng from his duty in Guangdong, interpreted the star to the emperor on May 30 as an auspicious star, yellow in color and brilliant in its brightness, that would bring great prosperity to the state over which it appeared. The reported color yellow should be taken with some suspicion, however, because Zhou may have chosen a favorable color for political reasons.

There appear to have been two distinct phases in the early evolution of this supernova. There was first a three-month period at which it was at its brightest; after this period it diminished, then returned for a period of about eighteen months.

Petroglyphs by the Hohokam in White Tank Mountain Regional Park, Arizona, and by the Ancestral Puebloans in Chaco Culture National Historical Park, New Mexico, have been interpreted as the first known North American representations of the supernova, though other researchers remain skeptical. The White Tank Mountain Regional Park petroglyph depicts a "star-like object" over a scorpion symbol. It has been argued that the scorpion represents the constellation Scorpius, despite the lack of evidence that the Native Americans interpreted the stars of that constellation as a scorpion.

The medieval Arab historian Al-Maqrizi also mentioned this supernova.

Earlier observations discovered from Yemen may indicate a sighting of SN 1006 on April 17±2 (15 Rajab, AH 696), nearly two weeks before its previously assumed earliest observation.