Changes
* Use the slit illumination to verify that the slit runs horizontally across the image again
'''If the rear-of-slit (ROSCam) camera window does not produce any images (though the exposures seem to count down), it probably needs a reset'''
* Check that you've got the light path right: guide mirror centred and the rear-of-slit mirror in the beam
* Then check that it's not an image scaling issue, by turning on the slit illumination (which is bright enough to show up under most circumstances)
* If you still don't see anything:
-exiting stop ROSCam exposures -exit the ROS ROSCam GUI
-press the "power cycle ROS camera" button from the TCS GUI
-wait 30s
-restart the ROS ROSCam GUI. -restart exposures
==Technical Notes==
