The fire was most likely caused by a flash of lightning, and scholars believe that the celestial apparition was actually the aurora borealis with a strong arc and flickering glows of light. The Nuremberg Chronicle mentions the fire too, although not the apparition, and counts as many as 3'000 people dead.
The text interprets the event as divine wrath against the Turks. Hence, the pamphlet appears to be a piece of political propaganda from the circle around Maximilian I, who strove for a new crusade.
This is the only traceable copy of this version (a close variant with nearly identical text survives in Munich, BSB). Woodcuts and especially single-leaf prints could only survive in such excellent condition in the protective environment of books, as is the case with the present sheet. However, pamphlets were only very rarely sewn into books as they were intended as ephemeral, instant news media, rather than objects to be preserved permanently.