to move to each field of the mosaic consistently over the course of the observing run, and avoid any gaps in the resulting mosaic. A fault in the offset guide head gave rise to errors of $\lesssim 5$arc sec. in the pointing of the fields; small enough not to result in any gaps within the mosaic.

The wavelength scale is calibrated using a series of Ne-Ar arc lamp exposures, taken throughout the night. Arc exposure times are 50s for the B3000 grating and 1s for the R3000 grating. Flux calibration was performed using the STIS spectrophotometric standard stars HD009051, HD031128 and HD075000 [^1]. In addition, a B-type telluric standard HIP8352 was observed to better correct for the OH and H$_2$O telluric absorption features in the red. The separation of these features by molecular species allows for a more accurate telluric correction by accounting for night to night variations in the column density of these two species. All data cubes were reduced using the PyWiFeS [^2] data reduction pipeline [@Childress14; @Childress14b].

All the individual, reduced cubes were median-averaged into a red and blue mosaic using a custom <span style="font-variant:small-caps;">python</span> script. The WCS solution of both mosaics is set by cross-matching their 