In AstroCam::Interface::dothread_shutter, timestring is set at shutter open (camerad/astrocam.cpp:2037) then overwritten at shutter close (:2060) before being written to the header at :2090. Every science frame's EXPSTART therefore equals the exposure end; MJD0/MJD1 are unaffected because they use separate variables. Confirmed in ngps_260729_0074.fits, where EXPSTART matches MJD1 to the millisecond.
last run on the flexure branch
In AstroCam::Interface::dothread_shutter, timestring is set at shutter open (camerad/astrocam.cpp:2037) then overwritten at shutter close (:2060) before being written to the header at :2090. Every science frame's EXPSTART therefore equals the exposure end; MJD0/MJD1 are unaffected because they use separate variables. Confirmed in ngps_260729_0074.fits, where EXPSTART matches MJD1 to the millisecond.
last run on the flexure branch