Some context: Chapter 27 is a 2007 biographical drama film depicting the murder of John Lennon by Mark David Chapman. It was written and directed by Jarrett Schaefer, based on the book Let Me Take You Down by Jack Jones, produced by Robert Salerno, and stars Jared Leto as Chapman. The film takes place in December 1980, and is intended to be an exploration of Chapman's psyche. Its title is a reference to J. D. Salinger's novel The Catcher in the Rye, which has twenty-six chapters, and suggests a continuation of the book.
The real Mark David Chapman is currently incarcerated at Wende Correctional Facility, on a guilty plea. Aside from two interviews with Larry King and Barbara Walters, both in 1992, he has not spoken with the media. However, Chapman did reveal the mechanics of his unraveling during those three days in New York City to journalist Jack Jones. The interviews were published in 1992 as Let Me Take You Down: Inside the Mind of Mark David Chapman, a book of Chapman's recollections of his act of violence. Chapter 27 is based on this text. The title "Chapter 27" suggests a continuation of J. D. Salinger's novel The Catcher in the Rye, which has twenty-six chapters, and which Chapman was carrying when he shot John Lennon. Chapman was obsessed with the book, to the point of attempting to model his life after its protagonist, Holden Caulfield.  According to the British music magazine Mojo, the title was also inspired by Chapter 27 of Robert Rosen's book Nowhere Man: The Final Days of John Lennon (2000). Rosen's book explores the numerological meaning of the number 27, "the triple 9", a number of profound importance to John Lennon. Lennon was deeply interested in numerology, particularly Cheiro's Book of Numbers, along with nine and all its multiples. It was Chapman's goal, according to Rosen, to write Chapter 27 "in Lennon's blood".  Like Chapman, Schaefer is a fan of both The Beatles and J.D. Salinger's novel The Catcher in the Rye, and said he began the script to try to understand "how someone could be inspired to kill anyone as a result of being exposed to this kind of beautiful art. It really bothered me, because Lennon and Salinger have always made me feel so much better, and so much less alone."
why is he incarcerated?
A: he shot John Lennon.

Some context: Gong are an international progressive rock band that incorporates elements of jazz and space rock into their musical style. The group was formed in Paris in 1967 by Australian musician Daevid Allen and English vocalist Gilli Smyth. Band members have included Didier Malherbe, Pip Pyle, Steve Hillage, Mike Howlett, Pierre Moerlen, Bill Laswell and Theo Travis. Others who have played on stage with Gong include Don Cherry, Chris Cutler, Bill Bruford, Brian Davison, Dave Stewart and Tatsuya Yoshida.
In August 1969, film director Jerome Laperrousaz, a close friend of the pair, invited them back to France to record a soundtrack for a motorcycle racing movie which he was planning. This came to nothing at the time, but they were subsequently approached by Jean Karakos of the newly-formed independent label BYG Actuel to record an album, and so set about forming a new electric Gong band in Paris, recruiting their first rhythm section of Christian Tritsch (bass) and Rachid Houari (drums and percussion) and re-connecting with a saxophonist called Didier Malherbe whom they had met in Deia. However, Tritsch was not ready in time for the sessions and so Allen played the bass guitar himself. The album, entitled Magick Brother, was completed in October.  The re-born Gong played its debut gig at the BYG Actuel Festival in the small Belgian town of Amougies, on 27 October 1969, joined by Danny Laloux on hunting horn and percussion, and Dieter Gewissler and Gerry Fields on violin, and was introduced to the stage by bemused compere Frank Zappa. Magick Brother was released in March 1970, followed in April by a non-album single, "Est-Ce Que Je Suis; Garcon Ou Fille?" b/w "Hip Hip Hypnotise Ya", which again featured Laloux and Gewissler. In October, the band moved into an abandoned 12-room hunting lodge called Pavillon du Hay, near Voisines and Sens, 120 km south-east of Paris. They would be based there until early 1974.  Houari left the band in the spring of 1971 and was replaced by English drummer Pip Pyle, whom Allen had been introduced to by Robert Wyatt during the recording of his debut solo album, Banana Moon. The new line-up recorded a soundtrack for Laperrousaz's movie, now entitled Continental Circus, and played at the second Glastonbury Festival, later documented on the Glastonbury Fayre album. Next, they began work on their second studio album, Camembert Electrique, later referred to by Allen as "the first real band album". It established the progressive, space rock sound which would make their name, leading, in the autumn, to their first UK tour. However, by the end of the year Pyle had left the group, to be replaced by another English drummer, Laurie Allan.
Did anything else big happen during those years?
A:
The new line-up recorded a soundtrack for Laperrousaz's movie,