A2463:Hires spectral scan of W51 with mocks
may08
Intro:
A2463 is doing a hi resolution spectral scan of W51
using the mock spectrometer in single pixel mode. To get the hi
resolution, both mock groups are being used. As an example, the cband
setup is:
- mock grp0 with 0 offset and bandwidth divisor 4 ==>172./4 = 43
MHz bw.
- mock grp1 with 37.464 MHz offset of each brd
- each grp 0 brd is offset by 75 MHz from the previous.
- The total coverage is: 43/2. + 6*75+37.464 + 43/2.= 530 MHz
- spectral resolution:5.2KHz=.3 km/sec @ 4750 MHz.
History:
- 100517: i took test data during the day on 3C138 (on/offs) at
different power level settings.
- 100518: early morning: first run on w51. on/offs only. Trouble
with spectrometer offsets for grp 1 (2nd grp).
- b0,bm1,bm3,bm5 s1g1 have center freq -2*(37.363) MHz from
where they are reported (and where they were supposed to be). Problem
was that the changes to /home/cima/Wapp/ to fix make the mock
spectrometer work correctly were not installed on the online version
(this was done 18may10 during the day).
- 100518: afternoon. installed patched /home/cima/Wapp on online
version. Need to use cima version svnwork. Took on/off's on J0738+177
at adjpwr settings of 60 and 120 cnts.
- 100519: day i took test data on blank sky: 3 5min on,offs
(adjpwr=120) and then 3 5 min on/offs on J0823+223
- 100526: afternoon switched cima mock.tcl to use ifbandflipped.tcl
routine to fix trouble with grp 2 offsets. Prior to this they were
being implemented inconsistently (probably an timing problem with
accessing scramnet info).
- 100528: tietrack was never run. telescope was a bit low
(1256.175ft instead of 1256.22 ft --> 1.4 cm low).
- 100602: sbh receiver warned up prior to observation.
Freq that were incorrect (top)
For data taken 100518 thru 100526 some of the
data in the second group were taken at the wrong frequency.
When these data are plotted, the frequency axis is showing the expected
value , not the value that was actually used. In the list below
the bands with bad frequency are listed. When it says bm3 2*df lo, the
reported frequency is 237.464 MHz above the actual data recorded.
- let the groups be grp 0 and grp 1 (just like the filenames
:b0s1g0,b0s1g1
- Let df=37.464 MHz (the offset in the digital mixer for group 1)
- 100518. 4500-5000
- grp0. bm 0-6 ok
- grp1.
- bm0 2*df hi
- bm1 2*df lo
- bm 2 ok
- bm 3 2*df lo
- bm 4 ok
- bm 5 2*df lo
- bm 6 ok
- 100521. 4500-5000
- bm0 2*df lo
- bm1 thru bm6 ok
- 100522. 4500 - 5000
- grp0. bm 0-6 ok
- grp1.
- bm0 2*df lo
- bm1 thru bm4 ok
- bm5 2*df lo
- bm6 ok
- 100523. 4500-5000
- 100524. 4500-5000
- grp0. bm 0-6 ok
- grp1.
- bm0 2*df lo
- bm1 thru bm6 ok
- 100525. 4000-4500
- grp0. bm 0-6 ok
- grp1.
- bm0 2*df lo
- bm1,bm2 ok
- bm3 2*df lo
- bm4 ok
- bm5 2*df lo
- bm6 ok
- 100526. 4000-4500
- 100527 -> data ok.
W51 data for each day (top)
The w51 on/off''s were scaled to kelvins and then
averaged for each day. The plots show:
processing: usr/a2463_xxmay10.pro
19may10: power of 2
jumps seen in spectra.
Spectral jumps with power of 2 channels spacing were
seen in the data.
The plots show various spectra
with their jumps (.ps) (.pdf):
- To emphasize the jumps, i computed on/off-1 for the 2 pols*
7bands*2 groups - 28 43 MHz bands. I then averaged them all together
(since the jumps are probably present because of location in channel
number, not frequency).
- adjpwr=30 means the input power levels was set so that the rms
input voltage at the 12bit a/d was 30 a/d counts.
- Top: 17may10 3C138 (3.8Jy @5GHz) 1 5 minute on/off -1 scaled to
Kelvins with the cals plotted vs channel number.
- The black spectra had adjpwr=30, the red spectra had adjpwr=60
- The green dotted lines are placed every 1024 channels. DC is at
the center.
- Center: 19may10 J0823+223 (1.9 Jy @ 5GHz). 3 5 min on/off
-1 scaled to kelvins were averaged (as well as the 28 band passes
for each on/off-1).
- adjpwr=120 counts
- You can still a small jump at 4096 +/- 2048.
- Bottom: 19may10 blank sky. 3 5min on/off-1 scaled to
kelvins then averaged.
- adjpwr=120
- You don't see any jumps.
Summary:
- adjpwr=30 jumps with power of 2 spacing are often and strong
center +/= 2048 strength is 150 milliKelvin.
- adjpwr=60 has a jump at center +/- 2048 of about (50 millikelvin).
- adjpwr=120 has the smallest (~ 5millikelvin but still
visible jump) at center +/- 2048
- No jump is seen when there is no continuum source.
- The on/off is probably canceling.
processing:
x101/100519/testa2463summary.pro
21may10: w51 on/off -1 (top)
6 5min on/off-1 position switched patterns were
computed and the averaged. The 2 pols were then also averaged.
The plot shows the
averaged spectra 4500
to 5050 (.ps) (.pdf)
- top: 4500 to 4755
- bottom 4745 to 5050
- The H alfa(black),beta(red), gamma(green) recombination lines
have been flagged. I used the rest frequencies so there is still the
doppler offset.
- OH and H2CO are also flagged. H2CO absorption goes below
the plots' vertical scale
processing: x101/100521/a2463.pro
27jul10:jumps in
xband freq channels (top)
On 27jul10 a2463 took data with xband receiver. The
setup was:
- Use single pixel mock setup. 7 boards, 2 groups
- use the digital low pass filter to get 86 Mhz bw in each board
- center the rf at 9500 Mhz
- synth centers are: 9050,9200,9350,9500,9650,9800,9950
- Offset grp 0 by - 37.464 Mhz, offset grp1 by +37.464
The jumps were along the freq axis. The trouble
occurred:
- Only grp 1 had problems, group 0 was ok.
- These are getting the same outputs from the mixer chassis. so
the touble is after the mixer.
- only polA had the problems, polB was ok.
- Jumps were seen in bm 0, bm1, bm5 boards.
- Data was taken with the cband receiver and no trouble was seen
(although this had a different mixing scheme for grp0,grp1)
- At different times, two different 1 ghz bands were used: 8-9ghz
and 9-10ghz. problems were seen in both of these bands.:
- trouble was also seen on 31jul10 in xband
files with problems 27jul10
fnum
|
bm
|
grp
|
freq
|
300
|
1
|
1
|
8237
|
400
|
0
|
1
|
8087
|
1100
|
1
|
1
|
9237
|
1200
|
0
|
1
|
9087
|
1500
|
5
|
1
|
9837
|
1900
|
1
|
1
|
9237
|
2800
|
0
|
1
|
9087
|
3100
|
0
|
1
|
9087
|
3500
|
0
|
1
|
9087
|
3500
|
5
|
1
|
9837
|
processing:
usr/a2463/freqjumps/27jul10.pro
home_~phil