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Gratings

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GMOS-N and GMOS-S use identical gratings and all gratings are available on each GMOS. However, some gratings are more heavily used than others and therefore spend more time in the instruments; see the grating statistics for recent semesters.

The table lists the properties of the GMOS gratings based on laboratory measurements. The resolving power R is given at the blaze wavelength, and refers to the resolution achieved with a slit width of 0.5 arcsec. The effective slit width of the IFU in the dispersion direction is 0.31arcsec, see the IFU grating/filter combination page for details.

Efficiency curves based on laboratory data are available. Note that the quantum efficiency of the detectors is below 5 percent for wavelengths longer than 1000 nm. 

None of the gratings are currently used in 2nd order.

GMOS Gratings
Grating Grating number*
 [North / South]		 Ruling density
[lines/mm]		 Blaze
wavelength
[nm]		 R Simultaneous
coverage
[nm]		 nm/pixel Efficiency
data
B1200 G5301 1200 463 3744 143 0.023 GMOS-N data
G5321 GMOS-S data
R831 G5302 831 757 4396 207 0.034 GMOS-N data
G5322 GMOS-S data
B600 G5303 600 461 1688 276 0.045 GMOS-N data
G5323 GMOS-S data
R600 G5304 600 926 3744 286 0.047 GMOS-N data
G5324 GMOS-S data
R400 G5305 400 764 1918 416 0.067 GMOS-N data
G5325 GMOS-S data
R150 G5306 150 717 631 1071 0.174 GMOS-N data
G5326 GMOS-S data

*The grating name is the concatenation of grating and grating number e.g. R831_G5302 for the Gemini North R831 grating.