LGS-AO Acquisition

Assume:
  1. We are locked on a target: the laser is propagating and the loops are closed.
  2. There are 3 people involved: the observer, the OA, and the LGS-AO operator.
    N.B. the OA and LGS-AO roles may be combined.


  1. Before moving:
    Observer
    Gives OA the new object.
    1. If on-axis, give the science target (lgs=1 target)
    2. If off-axis, give the tip-tilt star for the science target
    LGS-AO
    1. Opens the loops and shutters the laser via the "Open Loops" button on the "LGS-AO Acq. Widget".
    2. Notifies the OA that they can slew to the new object

  2. During Slew:
    Observer
    Set new rotator angle and mode
    LGS-AO
    Within the "LGS-AO Acq. Widget":
    1. Set AO Mode (NGS-AO, LGS-AO)
    2. Set DAR (usually Acq & Track)
    3. Set desired pointing origin (NIRC2, OSPEC, OSIMG) and notify OA of the desired PO
    4. Click "Setup Bench"
    5. Check that the tip-tilt star's name, Rmag, B-V color, and offset to the science target (if any) have loaded. If not, ask the observers for that info.

  3. Acquisition:
    Observer
    Identify the tip-tilt object for the OA
    OA
    1. Center the tip-tilt object on the "REF-L" PO using "Adj Pnt" so that FACSUM coords match the object coords
    2. Send the object to the desired PO and notify LGS-AO
    3. Turn off ACAM to preserve its shutter
    4. Request permission to propagate the laser from the Laser Safety Observers or verify no aircraft with TBAD
    LGS-AO
    1. Click "Aquire TT ref" from "LGS-AO Acq. Widget"
    2. If OA hasn't asked already, request permission to propagate the laser
    3. Watch "TT Sensor Stage" widget to see that the tip-tilt star is acquiring. If not, may have to abort acquisition (from MAORI) and retry.
    4. Laser will propagate and loops will close automatically
    5. Once "LGS-AO Acq. Widget" reports "Acquisition Complete", watch "LBWFS Manager" for the system to be optimized.
      N.B. "Optimized" will mean different things on different nights and with different objects. Bright tip-tilt objects will often show RMS Wavefront errors of <100 nm. On dim tip-tilt objects, errors may be >200 nm. Poor native seeing and high windshake will also degrade performance. There's only so much that AO can do--remember: garbage in = garbage out.
    6. While waiting for optimization, inform observers that they may take images of the tip-tilt object without dithering.
    7. Once optimized, if the science target is off-axis, offset to the science target if approved by the observer.
    8. Notify observer that they are ready to observe

  4. While observing:
    Observer
    Run dither scripts to observe objects. Keep in mind that for optimum performance, the dwell time in each dither position must be at least 2x the integration time of the LBWFS.
    LGS-AO
    Monitor the following:
    1. "TT Sensor Stage" to see that tip-tilt object counts stay constant
    2. "WFS Intensity Display" to see the laser return
    3. "LUI" to see all green
    4. "LBWFS Manager" to see that the RMS WF error remains low and fairly constant.
    5. "MAORI" to watch the loop status (especially after a dither)