ESI Data Format

ESI raw data files are in simple FITS format consisting of a single primary header/data unit (HDU) with 16-bit integer pixels.

An overview of the instrument is provided here, along with descriptions of the data format for the echelle mode, low-dispersion mode, and direct imaging mode.

ESI uses a single MIT-Lincoln Labs 2048 x 4096 CCD with 15 µm pixels, providing a pixel scale of 0.154 "/pixel. The full detector characteristics can be found here.

Two software packages are available for reducing ESI data: ESIRedux and MAKEE. Details on how to obtain and install the packages are provided on the referred pages. Additional notes on ESI data reduction are provided here and here, and on the ESI post-observing page.

More information is given on the Keck ESI page.