Background

The lspecfocus task is used for focusing LRIS in spectral mode. With some tweaking, it can also be used to investigate variations in spectral focus along the dispersion. See the instructions below.

Requirements

Procedure

  1. Launch IRAF on any HQ machine (preferable a fast one).
  2. Load the keck and lris packages.
  3. Run the lspecfocus task, being sure to set the following parameters:
  4. Mark 1 or 2 desired slit regions to perform analysis.
  5. After analyzing a region, specfocus will plot the variation in focus along the dispersion. At this point, use the following keystrokes in the graphics window to access different plots:
  6. When done analyzing results, type q in the graphics window to exit specfocus.
  7. If you selected a second slit region to analyze, repeat the previous 2 steps for the additional region.
  8. When done, results are saved to the specified logfile for reference.