16jan05 spider scan beam maps on 3c138

    Spider scans (heiles calibration scans) were taken with alfa on 16jan05 using the calibrator 3C138 (J0521+166, 9.1 Jy at 1420Mhz).The setup was 100 Mhz bandwidth centered at 1420 Mhz. Each pattern consisted of 4 60 second strips through the source (each strip rotated by 45 degrees). Each strip covered 6 beam widths.  With overhead,  a single pattern took about 6 minutes.  separate spider scan was done for each beam (centering that beam on the pattern). In all it took 43 minutes for the 7 spider scans. During this time the  za went from 7 deg before transit to + 3 degrees after transit. The rotation angle of the floor was kept constant at 0 deg.

Processing the data:

1. Fit the main beam and sidelobes for each strip using 1d gaussians (allow coma for the main beam).
2. Remove the sidelobe fit from each strip then do a 2d gaussian fit to the main beam
3. model the 8 sidelobe measurements with a fft of 8 terms in the sidelobe height, position, and width.

• Beam 0 (.ps) (.pdf): This is the center pixel.
• Beams1-6 (.ps) (.pdf): This has the outer 6 pixels arranged in the order they are on they sky.
• The az, za positions for the different beam maps were:

• beam	az	za
  0	-78.7	7.6
  1	-75.7	6.2
  2	-70.8	4.7
  3	-59.9	3.2
  4	-31.5	2.0
  5	21.6	1.8
  6	54.8	3.0