- Take Neon arcs with a grating (e.g. R1200R or R600R) and central wavelength so that the arc lines cover the whole CCD:

SYS> arc wyffos TIME "comments"

change the focus value (wslitf +/-NNNN) with steps of 500 units between each exposure, for a total of some 5 to 10 exposures (on Aug 2005  the best focus value was -2500 for H2400B and -3750 for R600R, and on April 2006 the best focus is 2000 for Echelle and 2250 for R300B and 1800 R1200B).

You can do a nice sequence with a file:

• wcallamp Ne
  
• wsetfocus XXXX
  
• arc wyffos TIME "focus XXXX"
  
• wsetfocus XXXX-500
  
• arc wyffos TIME "focus XXXX-500"
  
• etc ...
  
• wcallamp off

- Create a working directory and move into it (e.g. /scratch/whta/af2/focus).
- In this working directory, make a list of all the focus exposure files as in the /obsdata/ directory you will not be able to write some files.
(i.e. ls -1 /obsdata/whta/20051225/rXXXXXXX.fit > /scratch/whta/af2/focus/focuslist)
- start IRAF from the home directory and cd to the working directory

NOTE: If the IRAF login.cl file does not contain the QUICKLOOK tasks either:

• copy the file cp /home/whtguest/login.cl.QuickLook /home/whtguest/login.cl and run IRAF again
  OR
• type the commands
  set homeQUICK = "/home/whtguest/QuickLook/"
  task wyffosREDUC = homeQUICK$wyffosREDUC.cl
  task wyffosFOCUS = homeQUICK$wyffosFOCUS.cl
  task wyffosCALIB = homeQUICK$wyffosCALIB.cl
  OR
• just type task wyffosFOCUS = /home/whtguest/QuickLook$wyffosFOCUS.cl

- Type epar wyffosFOCUS, and change the parameters (filename with focus image, data directory, working directory, etc ...)
In the future you will be able to change the ouput file name (now by default focusALL.result)

- Run the task (:go to exit epar and execute the task). After about n*10-15 sec (n = number of exposure in the list)  you will got the results displayed on the screen and written into  file focusALL.result.

- Do not forget to apply the best focus value: wslitf FOCUS