1977-11-15 :       NASA announcement of opportunity for a Gamma Ray Observatory released (AO-OSS-3-77)

1977/1978:        COMPTEL proposal (see here)

1991-04-05:       Gamma Ray Observatory launch from Cape Canaveral; STS-37, Atlantis

1991-04-07:       successful deployment of the Gamma Ray Observatory

1991-05-16:       start of observation Phase I

1991-08      :       tape recorders start to show increasing error rates.

1991-09-23:       renaming to Compton Gamma Ray Observatory

1991-11-26:       tape recorder A shows high error rate; redundant tape recorder B used from now on.

1992-03-15:       both tape recordes have high error rate; main data transmission via TDRSS satellites starts;

fill in of data gaps due to incomplete TDRSS coverage with tape recorders. (Observation period 22)

1992-11-17:       start of observation Phase II

1993-05-04:       first tests for reboost fail

1993-08-17:       start of observation Phase III

1993-10-04:       start of first reboost sequence;

reboosts on 1993-10-04/17, 1993-11-19/23, 1993-12-15/17

1993-12-17:       first reboost sequence successfully completed

1994-10-04:       start of open (public) observation Phase IV - Cycle 4

1995-10-03:       start of Cycle 5

1996-10-15:       start of Cycle 6

1997-03-24:       start of second reboost sequence;

tests on 1997-03-24/25 and 1993-03-26/27

reboosts on 1997-04-01/07 and 1997-05-28/06-03

1997-06-03:       second successfull reboost sequence completed (see here)

1997-11-11:       start of Cycle 7

1998-12-01:       start of Cycle 8

1999-12-06:       loss of gyroscope #3

1999-12-09:       start of Cycle 9

2000-01-14:       first news in the press that CGRO will probably be deorbited soon

2000-05-30:       first engine burn to deorbit CGRO

2000-06-04:       CGRO deorbit completed; final destination: Pacific Ocean 3962 km southeast of Hawaii

last update 2016-04-07 by A. Agudo