ESI Modes and Instrument Properties

Modes

ESI has three basic modes:

  • Optical imaging
  • Low-dispersion spectroscopy (R=1000-6000)
  • High-resolution echellette spectroscopy (R=25,000-33,000)

Table 1 provides a summary of these modes, options, and features of ESI.

Table1: Modes

Mode Image or Dispersion Wavelength, Slit length, Pixel Scale
Echelle Spectroscopy high Wavelength range: 0.39-1.1 microns, R = 25,000-33,000 (depending on order number). Slit length of 20"
Low Resolution/Long Slit Spectroscopy low Wavelength range 0.39-1.1 microns, R = 1000-6000. Slit length of 480"
Optical Imaging imaging Wavelength range 0.39-1.1 microns, FOV = 69"x69", 138"x138", 128"x212", 120"x540" (depending on filter size), Pixel scale = 0.1542"

Instrument Properties

ESI employs a selection of fixed slit widths. Table 2 gives a summary of ESI's properties and design parameters. For more details, see ESI Data Format.

Table2: Instrument Properties

Property Echelle Mode Low Resolution Mode
Wavelength Range 0.39 - 1.1 micron 0.39 - 1.1 micron
Pixel scale (along dispersion) 0.120-0.168"/pix 0.123-1.70"/pix
Resolving Power 25,000-33,000 1000-6000
Slit Widths (arcsec) 0.30, 0.50, 0.75, 1.00, 1.25, 6.00, 0.3 (pinhole), 0.5 (pinhole), "MultiHole" (line of nine 0.5" pinholes) 0.30, 0.50, 0.75, 1.00, 1.25, 6.00
Slit Lengths 20" 480"
Groove Density 175/mm (grism not used in this mode)
Blaze Angle 32.3° (grism not used in this mode)