- go to the ''Advanced'' tab on the control GUI and click the ''grating angle initialise'' button (in the bank of buttons on the left)
* Once you have the correct grating in the spectrograph, enter the approximate starting angle (given in the grating table above) in the ''Grating angle'' box and click ''Go''. Compare the resulting arc spectrum with the arc maps shown in the table above, or in Chapter 10 of the old spectrograph manual.
* The software knows which order-blocking filters should be used with each grating, but it is still a good idea to check that the correct filter is selected (refer to the table above). If necessary, select the required filter from the drop-down menu at the bottom of the ''Instrument Setup'' pane and click ''Go''.