Checking alignment of INGRID with the pupil imager (PI)

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• Open the petals of the telescope
• Put the folding flat INGRID mirror in the beam. On the ICL type:
  hh:mm:ss> agingrid
• Datum the INGRID filter and pupil stop wheels:
  SYS> fwheel1 ingrid datum; fwheel2 ingrid datum; pstop ingrid datum
• Put the PI in the beam:
  SYS> pupil_imager ingrid in
• Put the ks filter and a reference pupil stop in the beam; e.g.:
  SYS> filter ingrid ks
  This will put filter ks in filter wheel1, clear position in filter wheel2 and cass-k in the pupil stop filter wheel
• Get the best instrument focus for the PI (change it and take glances to check it). At the moment, the best instrument focus for the PI is -1200 microns:
  SYS> ifocus ingrid -1200
  
• Take two images with this configuration: one with the dome lights on, and another with all lights off:
  SYS> run ingrid 2 "PI, ks, cassk, on"
  SYS> run ingrid 2 "PI, ks, cassk, off"
  
• Subtract the second image from the first one. You should get something similar to this:

Image 1 (r509141.fit.gz) Date: 15 July 2002 PI in, filter: Ks, pstop: cass-k, lights on	Image 2 (r509142.fit.gz) Date: 15 July 2002 PI in, filter: Ks, pstop: cass-k, lights off	Image 3 = Image 1 -Image 2 Date: 15 July 2002 PI in, filter: Ks, pstop: cass-k, lights on - lights off

• Take the pupil stop off from the pstop wheel and select the 'clear' position:
  SYS>pstop ingrid clear
• Take another two images (lights on and lights off) with this configuration and get the difference between the them. Use the same exposure time than before:
  SYS> run ingrid 2 "PI, ks, clear, on"
  SYS> run ingrid 2 "PI, ks, clear, off"
  

Image 4 (r509143.fit.gz) Date: 15 July 2002 PI in, filter: Ks, pstop: clear, lights on	Image 5 (r509144.fit.gz) Date: 15 July 2002 PI in, filter: Ks, pstop: clear, lights off	Image 6 = Image 4 - Image 5 Date: 15 July 2002 PI in, filter: Ks, pstop: clear, lights on - lights off

• The difference between the image with pupil stop in, and the one without it (after lights on - lights off), clearly shows the misalignment between the pupil stops and the secondary mirror; i.e. the misalignment between the instrument and the telescope, assuming that:
  
  1. the secondary and the primary mirror of the telescope are well aligned
     
  2. the optis of INGRID (specially foreoptics with respect to INGRID internal optics) are well aligned.

Image 7 = Image 3 - Image 6 Date: 15 July 2002

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