System performance
last monthly update: dec06
The performance of the various receivers measured
with the heiles calibration scans are listed by receiver and epoch. The
plots show the average of polA and polB. There are 3 sets of plots:
-
Gain [K/Jy], Tsys[K], SEFD[Jy/Tsys], and average beam width[Asecs]
-
coma parameter, 1st sidelobe height, main beam efficiency, and main
beam + first sidelobe efficiency.
-
Pointing errors [Asecs] vs az and za.
For receivers that cover a wide range of frequencies, the data will be
plotted with all frequencies combined, and then by frequency.
For the alfa receiver the data is first
plotted with all pixels together. The color is used to code the pixel number.
After the combined plot there are 7 more plots showing each pixel by itself.
For these plots the color is used to distinguish the source used.
The plots will be updated as new data becomes available. When something
occurs that may change the gain of the system (moving a horn, shimming
the elevation rails) then a new epoch will be started. There are
additional links to information for a particular measurement and for other
calibration info for each receiver.
Links to sections:
System modification history:
cumulative
number of scans by rcvr for last 12 months (.ps)
(.pdf)
check
the flux of the calibration sources
327 receiver
430 dome receiver
430 ch (linefeed) receiver
610
receiver
lband narrow
lband wide
alfa
sband narrow
sband wide (2-3 Ghz)
sband high (3-4 Ghz)
cband (4-6 Ghz)
cbandHi (6-8 Ghz)
xband (8-10 Ghz)
Miscellaneous multi frequency measurements
-
01mar03 thru lastModdate (reshimming of elevation rails to - current
date)
-
01sep02 thru 01feb03 (room temp amps to - reshimming of elevation
rails)
-
01sep01 thru 30jul02 (cooled receiver to - room temp amps installed)
430 dome receiver () (top)
-
01mar03 thru lastModDate (reshimming rails to current date)
-
01nov01 thru 01feb03 (start of data to - shimming of elevation rails)
430 ch receiver () (top)
-
01mar03 thru lastModDate (reshimming of elevation rails to - current
date)
-
30aug02 thru 01feb03 (insalled skinny dipole to - reshimming elevation
rails)
-
23may01 thru 29aug02 (installed fat dipole to - installed skinny
dipole)
-
01mar03 thru Dec03 (reshimming of elevation rails to rcvr removed).
-
21aug02 thru 01feb03 (horn focus change to reshimming of elevation
rails, pointing model).
-
01sep01 thru 20aug02 (reflector adjustment finished to horn
focus change).
-
01mar03 thru lastModDate (reshimming rails,new rcvr to - current
date)
-
21nov02 thru 01feb03 (horn focus change to - reshimming of elevation
rails, pointing model).
-
01sep01 thru 20nov02 (reflector adjustment finished to - horn
focus change).
The data is first plotted with all pixels together.
Color is used to code the pixel number. After the combined plot there are
7 more plots showing each pixel by itself. For these plots color
is used to distinguish the source used. The data is 100 Mhz centered at
1420 Mhz.
-
29nov04 thru lastModDate (start alfa calibration scans , to current
date)
-
21aug04
-
Tsys
. data taken from cal on/offs 21/22aug04. PolA top, Polb bottom. 100 Mhz
bands using cal value at center for entire band. Pixels/polA,polB may have
still be mixed up. Cal values are those measured in the lab. processing:
x101/mbeam/tsys/dotsys.pro
01mar03 thru lastModDate (ddmonyy reshimming of elevation rails
to - current date).
-
01sep01 thru 01feb03 (reflector adjustment finished to reshimming
of elevation rails).
14may04 thru lastModDate (diode replacement) to - current
date).
-
03mar01 to 17feb04(reshimming of elevation rails to - diodes replaced).
04feb04 thru lastModDate (horn lowered .8 inches,new cals
- current date).
-
03mar01 thru 13feb04 (reshimming of elevation rails to - horn lowered
.8 inches for focus).
-
25may05 thru lastModDate ( new amps installed to current date).
-
01apr03 thru 24may05 ( reshimming of elevation rails, pointing model
to new amps installed).
-
28aug02 thru 01feb03 (horn focus change to reshimming of elevation
rails, pointing model).
-
01sep01 thru 27aug02 (reflector adjustment finished to horn
focus change).
-
08feb04 thru lastModDate ( installation to current date).
-
15mar04 thru last mod date. (newcals,amps,rcvr work to current
date)
-
04sep03 thru Feb04. (new xband horn to new cal diodes.)
-
mar03 thru 03sep03 After rail shimming to new horn installed.
-
apr02 to 01feb03. New turret position to rail shiming.
Misc, multi-freq:
(top)
14feb05:
hpbw vs lambda (all rcvrs) for data taken 2004
14feb05:
hi frequency performance after reflector adjustments.
System modification
history: (top)
This is a short list of changes that could affect the system performance.
A more complete list can be found at system
modification history.
10dec06: updated pointing model 1az terms and az*sinza.
03/04dec06: x102 runs had offsets in model for testing. sin(za) az: -45.9*sin(za).
1az term for za: -6.7cos(az) - 6.8sin(az) . These values were added to
model. To goback to old model, subtract these values.
16jun06: lbw polB Cal. found loose sma feed thru inside dewar. Probably
causing the drifts in polB Tsys.
10apr06: sbn cal remeasured 15mar06. installed 10apr06. backdated to 14oct03.
Need to recompute the sbn data to used these new cal values. the old ones
were probably a little high.
04dec05: lbw polB cal value jumps 20%. remeaured cals on 23feb06.
23nov05: lbw diodes replaced
30sep05: station clock off by 1 second midnite to 8:30am. lbw
calibration data will have extra 15 asec pnterr.
18aug05: sbw cal cables changed. This changed the amount of cal getting
into the dewar. Need to remeasure the cals.
08aug05: new cband cals installed. backdated to 25may05 when
new amps were installed. recomputed cband data from may05 with new cal
values.
22jul05: lbw diode 1 died.. used diode 2 for cals until
new diodes arrive.
21jun05: installed new lbw cals (had a bug in diode1->polb...
fixed 09aug05).
01jun05 : lbw: found bad polA connection to probe in
dewar. found cracke polB cal cable in dewar..
25may05: cband reinstalled with new amps, cal values need to
be updated.
13mar05 Included 430ch data in system performance.
12mar05 oh filterbank installed for alfa.
29jan05 (check date) 430 filters to remove tv station
intermods installed polb ch and pola,b dome.
23jan05 recomputed alfa system performance using the
new cal values.
05jan05 added alfa data. Using old cal values from the
lab.
27dec04 cbh . model offsets az,za incremented by (-.28,-3.82).
data from x102 runs.
27oct04 the 327 data taken 27,28oct04 had a hybrid in
front of the receiver. It was used to create circular polarizations for
a vlbi observation.
09oct04 cband dewar brought down. found short in polA
cable inside dewar that was causing the tsys values to jump around.
12sep04 lbw cals measured 06aug04, installed 12sep04,
backdated to 04jun04.
04jul04 cband polA cal value jumps back (after dewar
warmed up and cooled down). note continues to jump around until 08oct04
when dewar brought down and short found in one of the cables in the dewar.
31may04 cband polA cal value jumps.
17may04 pointing model 15 installed after verify runs
completed. (sbn installed a few days before).
14may04 sbw diodes replaced, horn lowered 2.4 inches.
10may04 during this week calib scans were done with some receivers
with large pointing errors.
10may04 during week pointing model made sbn, verification other sources
with calib scans.
01may04 tertiary resurveyed into position
29apr04 horns resurveyed and moved into "best" position.
lbw,sbw,sbn not moved.
23apr04 lbw
polB cal value jumps.
21apr04 alfa installed, kevlar cables installed week before.
15mar04 xb receiver back up. Was in lab for cals,amps,
loose cables in dewar. remeasured cal values.
29feb04 pointing offsets cbh updated using calib runs
feb04.
14feb04 horn survey, repositioned horns, updated
pointing model. Larges move was lbw.
13feb04 sbh horn moved dow .8 inches to bring in focus.
New cals installed
10feb04 cbh installed
26jan04 leaf springs on the dome changed to stiffer ones
(approx. date)
14jan04 610 receiver moved on the turret floor.
07jan04 327,xband receivers moved on the turret floor.
10oct03 sbw cals remeasured. backdated to 15aug03. still
drifting.
02nov03 lbw gain curve from data 01mar03 thru sep03. back dated to
01mar03.
14oct03 8am. az encoder jumped by 3 teeth (about 16 asecs).
fixed on 16oct03.
05oct03 xband
cals remeasured on antenna test rangei valid from 05oct03.
04sep03 I think the Cal values on xband have changed
after new horn installed (see
measurements).. They need to be remeasured.
03sep03 new xband horn installed.
21jul03 xband. updated pointing offsets from calib data.
21jul03 xband installed new cal values from sky,absorber.
30may03 recomputed xband cals. uncorcal,0cal definitions were wrong on
measurement page.
18may03 loose cable cband cals. retightened cable and redid cals.
14may03 remeasured sbh cal values. diodes have been drifting.
22apr03: cband new cal noise diodes installed.
10mar03: corrected feeds offsets installed 07mar03.
07mar03: model 14 installed with feeds offsets (but offsets were backwards)
xxfeb03: dome lifted, elevation rails shimmed, model 14 installed.
21nov02: lbw horn focus changed
30aug03: 610 antenna switched from fat dipole back to skinny dipole
28aug02: cband horn focus changed
21aug02: lbn horn focus changed.
31jul02: 327 room temperature receiver installed.
02apr02: update xband turret position from theodolite survey.
23may01: 610 receiver switched to fat dipole.
06feb02: reshimmed xband horn position.
xxsep01: major adjustments to reflector surface completed.
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