---

Intro

    The system was calibrated on 01aug06 using 3C286 (24.3Jy at 430Mhz). This was the same source that was used on 29may06.   12 crosses were done with the yagi and 3 crosses with the linefeed.  The new low loss cable between the yagi and the amplifier had not yet been installed.  The setup was:

• 1.5 degree strips (12 crosses on the 430 yagi and 3 crosses with the linefeed) were done
• The yagi feed adds the polarization's together. The lrr1 polarization of the linefeed was used for the 430 linefeed measurements.
• The signal was centered at 430 Mhz and was passed through a 2 Mhz butterworth IF filter. Each strip took 90 seconds. The signal was detected with a .02 sec time constant and then  sampled at 100 hz.
• At the beginning of a set of crosses, the cal was fired for two seconds to measure Tsys. The cal values used were: yagi cal:124.9, linefeed cal: 50.3 K.
• 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 source was 24.3Jy
• The fit was iterated to get rid of some of the interference that occurs with a 1 minute spacing.

---

The 01aug06 data  (top)

• Fig 1 shows the individual strips:
• Top: yagi strips on 3C286.  Black are azimuth strips, red are za strips. The data has been smoothed by 5 samples.
• Bottom:  line feed strips.
• Fig 2: The average of  the yagi 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 9 db and 30 Amin from the peak.
• Fig 3 has the Gain and Tsys.  The gain is about 1.5 K/Jy. Tsys in 490 K at za of 11 and goes up to 500K at a za of 18.
• Fig 4 : sefd and beam widths. The top two plots are the sefd (source flux needed to equal the system temperature). The bottom two plots are the beam widths from the fits. * is the azimuth beam width and + is the za beam width. The yagi has a beam width is about 17 Amin.   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. New offsets were measured manually before taking this data. The pointing errors measured are relative to these new offsets. The top plot is the yagi and the bottom plot is the linefeed. The ch model was used for pointing with great circle offsets of: az: .75 deg, za: -.93 deg. The average yagi pointing errors are 3.56 Amin az and -.92 amin za. The pointing errors should be added to the offsets . These  pointing errors say the offsets should have been: az: .809, za: -.9453 deg.

---

Comparing the 29may06 and 01aug06 data   (top)

• Page 1 top: Gain (K/Jy) for yagi and line feed). The yagi gain on 29may06 was about 6% higher than 01aug06. The carriage house (ch) gains were the same on the 2 days.
• Page1 Bottom: Tsys (K) for the yagi and the line feed. The yagi Tsys on 01aug06 was a little higher than tsys on 29may06.
• Page 2 Top: Sefd for yagi and ch. The yagi sefd increased by about 10 % from may06 to aug06. This measurement does not use the cal values. That means that the offsets seen in the gain and tsys are probably real (and not problems with the cal changing). The   ch sefd remained pretty stable on the two days.
• Page 2 Bottom: The beam widths for the yagi and ch. These remained the same for the two dates.
• Page 3 pointing errors: The + are the az errors while the * are the za errors. These errors should not be the same since the 01aug06 position was a rough position to start with.

---

Conclusions:  (top)

•     The  comparison between the linefeed and yagi for 01aug06 is:

 

	yagi	linefeed
Tsys(za=13)	490	95
gain(za=13)	1.5 K/Jy	13 K/Jy
sefd(za=13) 3C286	330 Jy	8.5 Jy
beam width	17.5 Amin	10 Amin
1st side lobe (db)	az :-9.5 db za: -12 db	az:-12 db za:-14 db
az pnt err (avg) zapnt err (avg)	3.56 amin -.92 amin	-.13 Amin -.43  Amin
az pnt offset used: ch pnt offset used	0.75 deg -.93
az pnt offset measured za pnt offset measured	0.809 deg -.9453

• The yagi gain decreased and tsys increased between 29may06 and 01aug06 (before/after the move). This is probably real and not a problem with the cals since the sefd  also increased by about 10%. I wonder if the antenna is at the optimum position?

 home_~phil