GHRS Instrument Science Report 048 "GHRS Calibration Plan for Cycle 3" 6/93 David Soderblom, Stephen Hulbert and Lisa E. Walter Abstract excerpted from the report: The calibrations needed for the GHRS in Cycle 3 are modest: Only half an instrument (Side 2) is currently operated; Cycle 3 is only about six months long; Major changes to the instrument or its operations are not planned. However, Cycle 4 follows the Servicing Mission and so holds the promise of a revived Side 1 and of substantially better through- put with the Small Science Aperture (SSA). Thus we anticipate nearly having to start from scratch in calibrating the GHRS in Cycle 4 in order to make it fit for science observations. We present here a summary of the GHRS calibration plan for Cycle 3. It consists mainly of routine calibrations that monitor the state of the instrument and it has been designed so that the pre-Servicing Mission state of the instrument will be well-characterized for General Observers and Archival Researchers. Also included in this plan are a test of the extent to which the GHRS is vulnerable to telescope "breathing" and some images of the young cluster NGC 346 in anticipation of using the cluster for establishing the locations of the apertures of the GHRS in SMOV.