The Astro-2 mission began at UT 06:38:13 on 1995 March 2 with the
launch of the space shuttle Endeavour (STS-67). The orbit was
nearly circular at an altitude of 352 km and an inclination of 28.5 
.
Instrument activation started at 
Mission Elapsed Time
(MET), and first light occurred at 
MET with an observation of
Capella. Science operations began at 
MET,
and continued with only minor interruptions until the
instruments were deactivated at 
MET. Observing
efficiency was low during the first day of science operations while
the target acquisition and tracking procedures were refined, but was
in accordance with pre-mission expectations thereafter.
Pointing stability was frequently as good as 
RMS,
though the absolute pointing error could be several arcseconds.
The performance of HUT itself was nominal in nearly all respects throughout
the flight, with two significant exceptions: a discrepancy between
the best focus for the camera and spectrograph, and a gradual
decrease in the instrument throughput during the flight, which are
discussed in detail below.