Quick Review

  1. Focus the telescope using MIRA: recomended
  2. Acquire the target
  3. Coarse Alignment
  4. Fine Alignment:
  5. Start Spectroscopic Observations .

Slitmask Alignment

This checklist describes the procedure for aligning multiobject slitmasks on LRIS, assuming there are:

Focus telescope

Focusing the telescope before aligning a slitmask is recomended. The focus is strongly dependent on the LRIS physical rotator position and, to a lesser extent, the telescope elevation. It is generally recommended to re-focus the telescope when the telescope elevation angle has changed by 30° or more, and/or the instrument's physical rotator position (displayed as drive on the FACSUM display) has changed by 45° or more. In practice, this often means that refocusing is done for each slitmask, since each mask may have a different rotator position.

Acquire target

When the OA tells you that your target is on LRIS, check the following information on FACSUM to verify that your position is correct:

Coarse Alignment

In these steps, we put the stars into the alignment boxes. Either the red or blue beam of the instrument may be used for this step. Most observers choose to use the blue side since it is faster to reconfigure than the red. The following assumes the use of the blue side.
  1. Configure the appropriate side of the instrument for imaging:
  2. Set exposure time to 10-20 seconds, as desired.
  3. Take an image.
  4. When image starts reading out,
  5. Identify one alignment star on the image and measure the pixel coordinates in the PANE. Call these x1 and y1.
  6. Note the PANE positions of the corresponding box center overlayed on the image. Call these x2 and y2.
  7. Move the telescope by issuing a move command.
    Display tool move command where
    DS9 blue side movb x1 y1 x2 y2 lrisserver window
    DS9 red side moxvr x1 y1 x2 y2 lrisserver window

    The alignment stars should now be in their boxes; proceed with fine alignment.

Fine Alignment

In this step, we refine the positions of the stars within their respective alignment boxes to achieve optimal centering of the slitmask.
  1. Start Guiding:
  2. Take an image in 1x1 binning.
  3. Start IRAF:
  4. load the keck package and the lris subpackage
  5. cd to the data directory.
  6. Run do_lbox or optionally do_check_boxes
  7. Repeat steps 2 and 6 if necessary.