GHRS Instrument Science Report 078 "Multi-Orbit CVZ GHRS Observations and the Temperature of the Pre-Amp" A.B. Schultz and J. Bacinski Oct 14, 1996 Abstract Multi-orbit observations in the CVZ (more than about 15 hours) are affected by a temperature rise in the GHRS Pre-Amp, resulting in anomalous "absorptions" (so-called flaky diodes). This problem was first noticed during a Side 2 Cycle 5 program, 6086 (14 orbits), and repeated during Side 2 program 6072 (25 orbits). During long periods of CVZ observing, the GHRS Pre-Amp temperature will slowly rise to the high temperature limit. As the Pre-Amp temperature rises, the integrity of the Pre-Amp is compromised resulting in nonlinear amplification of input charge from diodes. This effectively results in the appearance of flaky diodes in spectra, as if a change in the threshold voltage had changed the sensitivity of diodes.