The system performance of Matthew's 430 Mhz dipole feed was measured on 06nov05 doing cross scans on J1330+305 (3C286) and J1419+064. These measurements  were done with the feed in the same position as the 22sep04 measurements. For these measurements the cal diodes were installed so we got Tsys as well and gain/sefd.  Cross scans were done on the 430 dipole and on the 430 linefeed. The setup was:
 

• 1 degree strips (4 crosses with  on the 430 dipole and then 4 on the linefeed) were done followed by 1.5 degree strips (18 crosses on the 430 dipole and 3 crosses with the linefeed). We switched to the longer strips so the first  sidelobe (30 arcminutes away) was included in the strip.
• The dipole feed adds the polarizations together. The lr1 polarization of the linefeed was used for the 430 linefeed measurements.
• The signal was centered at 430 Mhz and was passed through a 1 Mhz butterworth IF filter. Each strip took 60 seconds. The signal was detected with a .2 sec time constant and then  sampled at 10 hz.
• At the beginning of a set of crosses, the cal was fired for two seconds to measure Tsys. The cal values used were: dipole cal:42.1, linefeed cal: 50.5.
• 2d gaussians were fit to each cross. The fit included a rotation angle for the ellipse as well as a linear term in za (for changes in tsys). The first sidelobes were excluded from the fit.
• The flux used for the two sources was: 3C286=24.3 Jy, J1419+064=26.5 Jy.

• Fig 1 shows the individual strips:
• Top: dipole strips on 3C286.  Black are azimuth strips, red are za strips
• Center: dipole strips on J1419+064. Green are azimuth strips, blue are za strips
• Bottom:  line feed strips.
• Fig 2: The average of  the dipole strips after removing the system temperature. Each strip was rotated by the measured pointing error before averaging. The az strip is black and the za strip is red. The top plot is linear (in degK). The bottom plot is db below the peak.  The za beam width is a little larger than the az beam width. The az sidelobes are 10 db and 28 Amin from the peak.
• Fig 3 has the Gain and Tsys. 3C286 is in black while J1419+064 is in red. The gain for the dipole does not fall off in za as the linefeed. The dipole Tsys measurements of J1419+064 seem to jump: 4 low, 4 high. There was only 1 cal measurement for each of these groups. It could have been the cal measurement (but the sefd also shows this difference and it does not use the cal).
• Fig 4 : sefd and beam widths. The top two plots are the sefd (source flux needed to equal the system temperature). The two sources are color coded. The bottom two plots are the beam widths from the fits. * is the azimuth beam width and + is the za beam width. The dipole has a beam width of 18 amin and the linefeed has a beam width a little less than 10 amin.
• Fig 5: The pointing error measured from the fits. The values are in great circle arcminutes. The top plot is the dipole and the bottom plot is the linefeed. The ch model was used for pointing with great circle offsets of: az  .5, za -1.6  degrees. These measurements say that the offsets should have been: az:.4833 deg, za: -1.5483 deg.

Summary:

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