* SpUpNIC suffered severe grating instability problems that were incrementally reduced through various interventions, the last of which was the introduction (in early November 2016) of a pneumatically-actuated lock to clamp the grating mechanism at the user-defined angle. The lock is under software control and can thus be de-activated by the user in order to adjust the grating. We are delighted to report that the lock has eliminated the last of the play within the grating mechanism! Flexure remains inevitable for a Cassegrain spectrgraph as it swings about the sky on the back of the telescope. Therefore we still recommend that users bracket their target observations with arcs (taken immediately before and after the object exposures) so as to calibrate out any remaining shifts due to flexure.
* The angles listed in the second last column of the table below will get one into the range where lines are visible for a given grating, then adjust the grating angle (decrease/increase the angle to go more red/blue) to obtain the desired wavelength range - consult the sample arcs in the right-hand column of the table and the arc maps linked to below.
* Click on the following links for '''Arc Maps''' for '''[[G4]]''', '''[[G5]]''' and '''[[G7]]'''. Maps for the remaining gratings will be made available early in the new year.