Offsets in Wavelength Between the Large and Small Science Apertures of the GHRS

The wavelength shifts (offsets) between the GHRS LSA and SSA have been determined from the measured pixel shift for stars observed in both apertures. HD155763 (Zeta Dra) was observed with the first order gratings, while HD141556 (Chi Lupi) was observed with Ech-A and Ech-B, both as GHRS calibration proposal 6213. The target stars were first centered and observed in the LSA followed by slewing the telescope to position the target in the SSA. To eliminate movement of the carrousel between observations, No SSA ACQ/PEAKUPs were performed to center the targets in the SSA. This report summaries the observations, data reductions, and wavelength offset calculations. We find values for these offsets that are significantly different from the values determined in SV, and with better internal precision. Table 9 at the end summarizes these new values.