Just before starting regular observations even before taking standards, the telescope should Zero-Pointed. An OB with the Move_to_Gap option should be prepared. Use the Service Account 51021 -- 2p2w21 --60.A-9121(A).

Choose a star from the Astronomical Almanac close to the zenith.

Pick a star fainter that 4th magnitude.

Set up the esposure time to 0.5 sec.

Select the U filter.

Execute the OB.

Once the image has arrived to the INS RTD check how close to the reference pixel [X=4150, Y=3950] has the star actually fallen, then you will be asked Do You Want To Refine The Aquisition if the selected star is close enough the reference pixel (~ 10 pixels) answer NO on the pop up window, otherwise follow the instructions from the Observation Block (note down the Xr Yr of the bright star on the array from the RTD, then the Xr Yr of the reference pixel). The offset required to move the star to the reference pixel will be calculated and displayed, you will be asked to confirm the offset.

After the offset has been applied press the Correct Coordinates button on the TCS. To do this go to the TCS Setup Panel on the TELESCOPE portion of the panel click on Corr. Co. (at this stage you have zero-pointed the telescope!).

NOTE: Before applying the coordinate correction set the telescope to OFFSET mode on the virtual handset on the TCS (upper right corner on the screen).