Initialize Telescope Pointing

The 20-inch telescope has relative encoders and doesn't remember its position across power failures or TCS restarts (TCS assumes that the telescope is at zenith when it starts). Consequently, it's possible for the telescope to lose track of where it is on the sky if there's a power failure or an event (telescope maintenance, for example) that causes the encoders to disengage. Follow these steps to re-initialize the telescope coordinates.

1. In the SDSS control room check that the UT time in the TCS display is exactly correct. If you're not sure, or it is obviously wrong, start MOP and proceed as far as the initializeTelescope command. This command sets the TCS clock to the observatory network UT time. Exit MOP
2. At the telescope control panel, make sure that:
   • HALT MOTORS button is out.
   • Drives are on.
   • Tracking is off.

3. Find the bubble level and small hand mirror in the toolbox.
4. Put the bubble level on top of the filter box in the SW corner. Make sure it's flat against the box.
5. Use the telescope hand paddle to center the bubble exactly. The little hand mirror might help. SET speed is good for this after you get close with SLEW.
6. Position the dome at its home position (two red tape marks in the east line up).
7. Restart TCS.
8. You should be able to find an FK5 star somewhere on the CCD (but not necessarily near the center) using this method. If you don't, go back and try again, being especially careful in centering the bubble.

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