Updating the TPOINT model

IMPORTANT: The pointing model should be updated following a dedicated pointing run. A run of this nature has the following characteristics;

• Fullest possible coverage of AZ/EL space. Especially soucres at low (~25°) and high (~80°) elevation
• Observations taken in both quadrants 1 and 5 in azimuth rotation
• Ideally 20+ data points in total
• Observations taken consecutively to lie as close in time as possible
• Stable weather conditions

Pointing data files are held at the summit in directories/filenames like
/jac_logs/20090206/20090205-173329.pnt
Copy the relevant file into your working space.

Use the TPOINT commands to display the data with only collimations removed. If the residuals are large or show systematic trends with azimuth or elevation or other, then do a full 7-parameter model fit:

• tpoint
• indat yymmdd-hhmmss.pnt
• inmod /home/imc/pointing/tpoint/data/jcmt.mod_080528
• fix
• use ie ca ia npae aw an tf
• fit
• call a9     (or 'g s a' or 'g a a' or 'g z z' or gdist, gscat, ghyst, gsmap, gdist, gam etc)
• gc p tpoint.ps (to produce tpoint.ps of plot shown in xwindow. The option p produces a colour plot whilst b would produce black and white)
• slist   (to tabulate results/residuals)
• mask n   (to remove the nth datum, after which you could repeat the fitting and rerun slist and call a9)
• outmod new-model-name
• quit

If the fit is an good improvement - i.e. if dS,dZ are significantly smaller than after the fit using just IE & CA, and if the changes to any of the 7 parameters is significant at the 3-sigma level - then the updated values of the (7) model parameters should be entered into the file

          /jac_sw/itsroot/src/tcs/thi/THI.tide

on a summit machine, after which you should do

            >source /jac_sw/itsroot/etc/login
            >make

and then update the CVS using

          >cvs commit -m "(pointing model updated -yyyymmdd)"

The TCS should be restarted follwing this to ensure the new model is picked up.