Intro
The steps in processing the data
Map positions raw data
    Plot: sampled map positions for each field (.ps) (.pdf).

Removing Tsys.

The individual maps by field
    The  average maps for each field (.gif)

Mosaicing the 11 + 4 maps together

Intro: (top)

    Data was taken aug-dec09 and dec10. The a2125 data was then included in the final combined map.

 

mapname	map center ra, dec	date taken
Field1	00:51:00, 35:15:0	aug09
Field2	01:10:30, 35:15:00	aug09
Field3	01:09:30, 31:57:00	oct09
Field4	01:08:30, 38:15:00	aug09,oct09
Field5	01:07:30, 24:27:00	aug09
Field6	00:50:30, 24:27:00	aug09
Field7	00:33:30,24:27:00	aug09
Field9	00:16:20, 26:05:00	aug09
Field11A	01:27:20, 31:21:00	dec10
Field12	01:26:30, 28:15:00	aug,oct,dec09
Field14	01:25:00, 25:09:00	dec10
a2125 fields (_05 added to fieldname)
Field1_05	00:50:38 , 23:31:00
Field2_05	00:34:42  , 28:31:00
Field3_05	00:50:55 , 32:01:00
Field4_05	00:34:25 , 32:01:00

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The steps in processing the data  (top)

• see a2125 steps in making the maps.
• Mosaic the 11 + 4 fields together.
• Mosaicking was done on a pair wise basis looking at the ra and dec overlaps. This is not the optimum method but ...
  

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Map positions   (top)

• Pages 1-3 shows the az,za positions for each field
• Page 4 has the ra/dec sampled positions for each field.

Removing Tsys (top)

• Create a model of the za dependence of Tsys using the x102 data (tsysX102M). Normalize this so tsysX102M(za=10) is 1.
• For each map (ra,dec strips processed together):
• fit for the scale factor TsysData(za)=tsysX102M(za)*scale
• TsysRemoved= TsysData(za) - tsysX102M(za)*scale  .. this is done separately for pola, polb.
• If the actual Tsys changes over time ,this should help correct for that.
• If the cal Values change (without remeasuring them), then the 0 of tsysRemoved should be ok, but the scaleFactor of tsysRemoved will still be off (since we didn't scale it by the change in the cal values).
  

• Plot (TsysA/TsysB -1) before fitting or corrections
• The data has been converted from correlator counts to kelvins using the cals (after cal fitting).
  
• Top: TsysA/TsysB-1 vs za
• 2nd: TsysA/TsysB -1  vs az
• bottom:TsysA/TsysB -1 by field
  
• dashed green lines separate fields.
• Cal scale factors by field (.ps)
• These values are computed from the cals on every strip. they convert from correlator counts to Kelvins.
  
• black (polA) ,red(polB) after cal fitting
• green(polA), blue(polB) before cal fitting
• Cal fitting takes adjacent cals (with no attenuation changes) and does a linear fit to the measured scaling factor ( throwing out outliers). The fit is then used to convert correlator counts to kelvins rather than the individual measurements.
  
• If there are no outliers than the blue,green overlay the black, red traces.
  

• Global fitting of all the data:
• Plot Tsys vs za and then fit for all data at once (.ps)
  
• Show fit residuals by field (.ps)
• Fitting Tsys by Field.
• Remove tsys by field (rascans, decscans separate). plot Residuals for each field.
• Each page is a separate field.
  
• top: polA, bottom PolB
• Black points are the rascans, red points are the dec strips
• When the images are made, Tsys is removed from the ra and dec scans simulataneously
• We left them separate here to see if the ra, or dec scans had any outliers.
• Tsys residuals by field (rascans and decscans together).
  
• Same as above plots but the scaling fit is done with ra and dec strips together. This is how the images are made.
• Black is polA, red is polB.
  
• The scale factor and errors are included in the title for each plot.
• Fields11A,12,3 Some fields that didn't mesh well (.ps)
• Each page shows the Tsys-fit (by map) plotted vs rahr and dec to see if there is any obvious bad data.
• Black is pola, red is polB
  
• Page 1: Field11A
• Bottom: decstrips vs ra. raHr 1.51 -> end polA has slope to it.
• Since i didn't use polA, shouldn't matter.
  
• Page 2: Field12
• Frame 2 ra strips vs dec.
• decs 26->26.6 polB is low. This will be part of the overlap with Field14 below it.
• Frame 4: decstrips vs ra
• ra 1.27 -> 1.37 hrs, PolB is high and polA is low. This is part of the overlap with Field 4 (to the right).
  
• Page 3: Field3
• Frame 4 dec strips vs ra.
  
• looks like a jump at middle of map: ra 1.15 hours. Both polA and B go from low to high

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The individual maps.  (top)

1. grid the ra driven and dec driven maps separately to the same grid.
• Grid spacing was 3 arcminutes.
• The gridding function used a gaussian with a fwhm of 5.5 (it was repeated with a gaussian of 11 aminutes).
• The gridding function extended out to about 30 arcminutes.
• A sin projection was used to project onto the  2-d grid.
2. basketweave the two  maps. Create an average map and a difference map after basketweaving.
• The basket weaving will try an remove offsets in strips.

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Mosaicing the fields.  (top)

1. take each pair of overlapping maps.
   
2. Interpolate the first map of each  pair to the grid position of the second  (within the overlap region).
3. compute  mapRaDif=(map2 - interpolated Map1) in the overlap region
4. Fit a linear polynomial to the differences as a function of the ra position
5. Correct the two maps by subtracting half the difference from map2 and adding half the difference to map 1
6. Repeat steps 1 5 with the corrected fields, using the dec overlap of the pairwise maps.
7. 21feb11: changed so that 1-6 only corrects 20% of the difference. It then interates 1-6 5 times. This gets rid of jumps caused by the correction.
   

• the units are Janskies (multiply by 10 to get kelvins).
  
• Pages 1-3. Overlap in ra direction with  map1-map2Interpolated plotted  vs ra.
• The red line is the fit  vs ra.
• Page 2, frame 2 Field12 - Field11A vs ra has a  large offset and slope
  
• Pages 3-7. Overlap in dec direction with map1 - map2Interpolated plotted vs dec.
• Each set is the start of iteration i (i=1 to 5). the last one is when everything is done. The set shows how the correction progresses with a correction factor of 20% per iteration.
• Pairwise difference overlap region:Iteration 1 start (.ps) (.pdf)
  
• Pairwise difference overlap region:Iteration 2 start (.ps) (.pdf)
  
• Pairwise difference overlap region:Iteration 3 start (.ps) (.pdf)
  
• Pairwise difference overlap region:Iteration 4 start (.ps) (.pdf)
  
• Pairwise difference overlap region:Iteration 5 start (.ps) (.pdf)
  
• Pairwise difference overlap region:Iteration 5 end (.ps) (.pdf)
  

The final mosaiced maps (.gif):

• The  x,y positions are just grid points along the ra,dec direction.
  
• This used a 5.5 arcmin gridding function. The final resolution is about 14 arcminutes.
Processing: combinemaps.pro

Notes on the fields.  (top)

• Trouble with PolA 2009 data.
  
• There were large jumps in polA. see 10aug09
• Ended up just using polB when making final map (but it is circular).
  
• Dec10: TsysField11A, TsysField14
  
• Looking at the globally fit data, TsysA - TsysFit has a median of -9Kelvins for these 2 fields taken in dec10.
  
• TsysB11a -TsysFit is +4K
• Must be that calA has changed since the calibration fit values were made.
• 
  
• Field11A,Field12 dec overlap.
• there is an offset in the dec overlap of these fields of .1 Jy and a slope of about .2 Jy across the map. This is removed during the mosaicing.
• Field 12.
• Dec strips at low ra , polA is low and polB is high.