From the longer Wikipedia page 
The Tulli Papyrus is an oft-cited document of questionable origins that some have interpreted as evidence of ancient UFOs.
During a visit to Cairo in 1933, Alberto Tulli, a director of the Egyptian section of the Vatican museum, supposedly found an interesting papyrus in an antique shop. The price was too high, however, and a copy was made of the text, which was then re-copied, replacing the original hieratic script with hieroglyphic. It is this copy of a copy, i.e.
hieratic original → hieratic copy → hieroglyphic copy
that has been translated and widely reproduced. The copy is characterized by "deletions", where parts of the text are elided. These may be deliberate attempts to make the content appear mysterious; or they may be legitimate notations showing gaps or holes in the original manuscript.
An Italian nobleman, Prince Boris de Rachewiltz, claimed to have found the original papyrus, "untranslated and unpublished," among the papers which had been left by the deceased Tulli. In introducing his find to Doubt magazine in 1953, he described the original fragment as written in hieratic, that the script was faded, and that it had several lacunae (gaps) in the text.
He named an Egyptologist, Étienne Drioton of the Egyptian Museum in Cairo, as the one who had actually retranscribed it from the original hieratic script into the more familiar hieroglyphics. Drioton was not only on staff at the Cairo Museum, he was also an authority in his own right] and is routinely referenced by others in the field. While de Rachewiltz asserts that the papyrus forms part of the library of Thutmosis III, nothing in the document refers to a pharaoh by name - somewhat regrettable, but not without precedent.
The resulting transcription has been translated by Boris de Rachewiltz and several others. The content seems to revolve around "circles of fire" that flew through the sky on two separate occasions, separated by a few days. While some sources discount Rachewiltz's credentials, he was a well-known scholar, and some of his works are still used today (e.g., "Maxims of the Ancient Egyptians," translated by Guy Davenport in 1987). The quality of his translation is considered acceptable; moreover, the transcribed Egyptian text that survives stands up to scrutiny and does not appear to be an obvious hoax.
Rachewiltz's translation caused some controversy. In recent years it has been a subject of discussion in UFO literature. The Vatican denies having either copy made by Tulli. It is currently believed that the document had never been a part of the Vatican's collection, and remained Tulli's personal property. Upon Tulli's death it was supposedly left to a relative and lost. Lately a copy of the original transcript, as published by de Rachewiltz, is reported to have been found in an American library by anthropologist and UFO proponent R. Cedric Leonard, who proceeded to translate it.
In summary, the Tulli Papyrus is not a papyrus, but rather a translation of a modern transcription of an alleged Egyptian document, the location of which is currently unknown, and has only been reported by three individuals (i.e., Tulli, Drioton and Rachewiltz). No scientific analysis can be made without examining the original for authenticity. The so-called 'circles of fire' might possibly be explained by natural phenomena; however Leonard's preferred rendering 'fiery disks' makes this interpretation a little more problematic.
A recent study by Franco Brussino, published in Egittologia.net web pages, revealed that the Tulli Papyrus is a forgery, made up by a kind of collage of fragments taken from nine different papyruses. The source was the Egyptian Grammar by Sir Alan Gardiner, considered the most thorough textbook of the Egyptian language, published in 1927.