lbw gain curves after horn focus moved.


link to gain curve plots

    The lband wide (lbw) horn was lowered 3.67 inches on 21now02 to put the phase center in the correct location. This changed the gain as a function of azimuth and za. Calibration scans from 21nov02 to 31dec02 were used to create a new set of gain curves. The final fits were done only as a function of za. This was mainly because of the limited az coverage.  With the feed no longer far out on the edge of the focus curve, small changes in focus will no long affect the gain as much as before.

     The cal values used were the original cal values of gene lauria. The plots show the gain data (black) and the fits (red) for the 4 frequencies:  1175,1300, 1375,  and 1415 Mhz.

     The  system performance computed from this data set (including the SEFD which is independent of the cals) is also available for inspection.

    The idl routines gainget() or corhgainget() will now return the lbw gain for data after 21nov02 using these fits. Since there is no data above 1415, the values at 1415 will be used for 1415 to 1700.The coefficients can be found in the ascii file  data/gain.datR5 (this is provided in the AO idl distribution for correlator routines). You can also find a copy of it at AO in /home/phil/idl/data/gain.datR5.

processing: x101/lb/dec02/