====== Recovering from a Stall ======

^ ^Jun 14, 2021, P Gabor et al.^^ ✔✘ ^ 
|Control room | :!: Mirror cover must be open. :!:  || |
|Control room | 8-) If you want to close the dome slit (may be a good idea esp. when windy), close the mirror cover (assuming that the **breaks came on** when the stall occurred), than close the dome slit, and then open the mirror cover again. || |
|Control room |Turn on the dome floodlights || |
|Control room |''Breaks off''  :!: **Be ready to set the breaks again** if the telescope slumps in elevation when the breaks are released (watch the telescope in cameras, 8-O and watch the elevation value in TCSglue) || |
|Control room |Keep dome tracking on || |
|Dome, lower lvl |Inspect the "flippers" and find the double-headed bumper. You will need to spin the telescope back to its stow azimuth. Remember that: || |
| ::: |=) the double-headed bumper "lives" in the South || ::: |
| ::: |=) from your vantage point at the dome's lower level, a flipper may show a green patch or no patch; you can never see a red patch from there || ::: |
| ::: ^ Safe (recommended) ^ Less safe | ::: |
| ::: |=) if both are green, simply align the arrows meticulously |if both are green, simply align the arrows **within a few inches**  | |
| ::: |=) if one is green and the other has no patch, spin towards the latter, flipping it to green; then keep spinning until the arrows align perfectly |if one is green and the other has no patch, spin towards the latter, flipping it to green; then keep spinning until the arrows align **within a few inches** | ::: |
|Basement |__Disable the hydtrostatic bearing:__ Turn ''Stage 2'' off. |//Does not apply// | |
|Dome, upper lvl |Move the telescope to zenith |Step onto the telescope yoke platform carefully (avoid imparting angular momentum in azimuth), and move the telescope to zenith | |
|Dome, upper lvl |Turn the derotator (considerable force is required) back to home, untwisting the cable bundle  |Still standing on the yoke platform, turn the derotator (considerable force is required) back to home, untwisting the cable bundle | |
|Dome, lower lvl | |Align the Azimuth arrows **accurately** | | 
|Dome, upper lvl |Bring the dome to its home position (gently spinning the encoder wheel) || |
|Basement |__Enable the hydrostatic bearing:__ Turn ''Stage 2'' on. |//Does not apply// | |
|Control room |Set the breaks || |
|Control room |Close the mirror cover || |
|Control room |Close the dome slit (if open) || |
|Control room |Turn Thermal control off || |
|Control room |Stop ''Autocollimation'' || |
|TCS room |[[vatt:vatt_reboot_vatttel|Reboot VATTtel]] || |
|Control room |Close and open ''TCSglue'' || |
|Control room |Start ''Autocollimation'' || |
|Control room |Turn Thermal control on || |
| ^Done! || |