System performance after reflector adjustments 2004.
05jan21
The 3 reflectors were adjusted during 2004. The
dates were:
-
tertiary: 12oct thru 30 oct04
-
secondary: 7jun through 29jun04
-
primary: start nov04 through jan05
Data taken before the adjustments were compared to data after (or nearly
after) the adjustments to see how the performance of the telescope changed.
The higher frequency receivers were used since they are more sensitive
to reflector errors. The receivers and dates for their data sets are:
| receiver |
frequency (Mhz) |
before dates |
after dates |
sources After |
| cband |
5000 |
may03 to jun04 |
dec04 to jan05 |
B0134+329 3C48
B0316+162 CTA21
B0518+165 3C138
B2116+180 |
| cband hi |
6900 |
march 04 to jun04 |
dec04 to jan05 |
B0428+205
B0518+165 3C138 |
| xband |
9000 |
march 04 to jun04 |
dec04 to jan05 |
B0428+205
B0518+165 3C138
B0758+143 3C190 |
The cband comparison limited the before sources to the same ones that
were measured after the adjustments (so there should be less question about
source fluxes). The Cband hi and xband receivers used all sources
taken during the "before" dates (since there were not many common sources).
The plots show the
gain, Tsys, SEFD, and average beam widths (.ps) (.pdf)
for the 3 receivers. Black is used for the sources taken before the
adjustments while red is used for data taken after the adjustments.
-
Fig 1: cband at 5000 Mhz. The "after" sources B0134+329,
B0316+162 were taken on 17jan05. The gain looks to have improved a small
amount.
-
Fig 2: cband hi at 6900 Mhz. There isn't enough overlap in
az, za to do a good before/after comparison (cband high was not installed
until mar04). On the other hand, most of the after gains are higher
than the before gains.
-
Fig 3: xband at 9000 Mhz. This receiver shows the largest improvement
in gain. You need to be a bit careful since the receiver was worked on
and new cals were installed in mar04. It is also the most susceptible to
rain.
processing: x101/050117/reflectoradj.pro
home_~phil