Dome flats give a measure of the pixel-to-pixel sensitivity variations over the CCD. The dome's white flat-field screen is not perfectly evenly illuminated by the lamps on the top end of the telescope, but the light goes through the slit, gets collimated, diffracted and re-focussed, so that is not a problem. We do not use the sky for this as you would get spectra of the Sun!
- First check the observing floor for ladders or obstructions. If you're observing remotely you can use the webcam, or if you're in the dome just pop upstairs.
- On the TCS, click the grey "FLOOR" button near the top to change the telescope control to "TCS".
- Click the red "Telescope Power is OFF" button on the top left. Telescope power will switch on, the button will turn green, and the various subsystem statuses will be populated.