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ALFOSC slits: quality control

If in doubt on the quality of the slit jaws of a slit, please make sure the slit is clean (e.g. blow air), and take a test image of the slit. The collapsed image can be compared with the graphs on the main slit page.

Instructions for horizontal slits:

  • window with 'ysize 400' and 'ybeg 821'
  • turn on the 5 domeflat lamps at full power
  • open mirror cover
  • use default ALFOSC focus
  • put slit in beam
  • no filters, no grisms
  • exp 0.4 (slit image)
  • take slit out
  • exp 0.4 (flatfield)
  • switch lamps off
  • dark 0 (bias)
  • resetxy
Subtract bias from flat and slit, and divide debiased slit by debiased flat. Collapse the 2D frame by summing the pixel values across the slit profile (e.g. with IRAF blkav or apall). The resulting slit transfer function gives as a function of pixel along the slit, a countrate equal to the effective width of the slit in pixels.

Back to top Last modified: 22-Oct-2004