Changes

*In the case of biases, "slow" and "fast" refers to the readout mode and for your science files that can be checked by looking at the "HSHIFT" keyword in the header: slow=0.05 and fast=5.0*Mookodi's derotator cable-wrap does not have a full 360 degree range so the result is that some observations are taken with north up in the images while others flipped 180 degrees with north down in the images. Your science images can be a mix if a derotation occured during your observation sequence. There is also subtle changes in the telescope throughput for the two orientations so you need to use flats taken at the same orieantion orientation as your science images. The supplied reduction script will warn you if you are using flats at a different orientation than your science frames. If you are reducing the data yourself with your own software, you can check which orieantion your scince science image was taken by using the value of the ROTANGLE and ROTSKYPA header keywords. The sky-angle is = ROTANGLE-ROTSKYPA. If the sky-angle is close to 0, 360 or -360 your images are with north DOWN. If the sky-angle is close to 180 or -180 your images are with north UP.