Sbw cal values measured 26sep08

26sep08

Links to PLOTS:
Plots for entire band
Hcorcal in Kelvins (all bands) (.ps) (.pdf)
Over plotting all cals (.ps) (.pdf)
Comparing new, old calvalues (.ps) (.pdf)
Compare Tsys with old/new cals (.ps) (.pdf)

   
HCORCAL (by subband)
1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
Fits to the Average CalDeflection/Tsys
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
Hcorcal in Kelvins
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
     CalDeflection/Tsys for each pass
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
     Fits to the CalDeflections for each pass
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf

OTHER CALS (by subband) 1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
Avg Cal Values in K (and fits)
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
     CalX/hcorcal for 4 the passes
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
     Fits to CalX/hcorcal
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf

Links to SECTIONS:
Why the cals were remeasured.
Measuring the high correlated cal using blank sky and absorber
Measuring the other cals on blank sky relative to the high correlated cal.
Comparing old, new cal values


Why the cals were remeasured.

    On 18aug05 the cal cables were replaced on the sbw receiver. Looking at the tsys measurements using the old cal values, this caused a jump of Tsys of about 30% (lower.. so more cal was now getting into the dewar). On 26jul06 the dewar was warmed up and then cooled down again. This caused a jump of 10% in the system  temperature. In apr07 the dewar was shutdown for the painting project. It was turned on at the beginning of 2008. It left warm for a large fraction of 2008 because of the cutback in supported receivers.


Measuring the high correlated cal using sky and absorber: (top)

    The high correlated  cal value (diode 1 going to polA and polB) for lband wide was measured on 26sep08  using  the sky/absorber technique.  The sky observations tracked blank sky starting at 5 am . The sky was clear. The absorber measurement was done around 9:00 am. In both cases (sky and absorber) the wbw filter bank was used. 

    The temperatures used in the computation were:
 
Tabsorber 301 K
Tsky 6 K
Treceiver from test shack sep01
Tscattered 14 K

    The sbw filterbank breaks the band up into: 1.7 to 1.88, 2.04 to 2.40, an 2.6 to 3.10 Ghz. The 100 Mhz bandwidth of interim correlator ended up taking 5 separate measurements to cover this range: (1700-1800,1780-1880, 2040-2140,2100-2300, and 2600-3100).
    This range was covered 6 times on sky and on 6 time on absorber. The processing wants contiguous data so the following processing was done for each of the 5 contigous frequency sections:

    The results of the reduction are:

HCORCAL
1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
Fits to the Average CalDeflection/Tsys
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
Hcorcal in Kelvins (individual sections)
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
Hcorcal in Kelvins (all bands) (.ps) (.pdf)

    Diagnostics:

    The first set of plots show the calOn-caloff/caloff for each pass through the data. The second set over plots the fits to each pass to see how stable the system is.


1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
     CalDeflection/Tsys for each pass
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
     Fits to the CalDeflections for each pass
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
processing: x101/calsbw/cals/sep08/hcorcal/sbwinp.pro,sbwfit.pro,sbwcmp.pro,sbwplot.pro,sbwdoit.pro


Measuring the other cals using sky and the high correlated cal (top)

    The high correlated cal was measured (see above) using sky and absorber as the hot and cold load. The other cals were then measured relative to the high correlated cal on 26sep08 starting around 5:00am. Blank sky was tracked,  the filter bank was used,  and the following cal sequence was run:     100 MHz at a time was measured (4 by 25MHz) going from 1700 to 3100MHz (in the 5 frequency sections).  The cal was cycled on/off for 3 secs at each step.  The entire frequency range was repeated 4 times.
    The ratio (calOnX-calOffX)/caloffX was computed (X is the other cals) and then it was divided by (calOnHcor-calOffHcor)/calOffHcor). A spectrum for the entire pass was then constructed of the other cals relative to the hcorcal. The spectral fits for the 4 passes were averaged. The average spectra was  multiplied by the hcorCal value in kelvins (this removed the hcorCal shape). The resulting spectra was fit with an nth order harmonic and 1st order polynomial. For more info see computing the cal value.

   The results of the reduction are:


1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
Avg Cal Values in K (and fits)
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
Over plotting all cals (.ps) (.pdf)

Diagnostics:


1700-1800
1780-1880
2040-2140
2100-2400
2600-3100
CalX/hcorcal for 4 the passes
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
Fits to CalX/hcorcal
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf
.ps .pdf

Compare old,new cal values

    The first plot  compares the new and old cal values (.ps) (.pdf)  :
    The second plot compares Tsys measured at 2290 for 27jul08 to 25sep08 (.ps) (.pdf):

processing: x101/sbw/cals/sep08/othercals/sbwinp.pro,sbwcmp.pro,sbwfit.pro,sbwplot.pro


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