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KFPA and Pipeline Data Reduction Guide

Note that much of the content of this documentation is out of date. Please refer to the GBT Pipeline documentation instead!!!

The KFPA was developed simultaneously with a data reduction pipeline. Here we describe tools to check the status of an observation and run completed blocks of observations through the pipeline to produce images. Finally we describe methods for combining blocks of calibrated observations into images of complete regions.

Data Reduction Guide

The latest release of the data reduction guide is available as a PDF:

The remainder of this page expands on this guide and includes executable commands.

GBTIDL tools

The observer is advised to make a short observation of a target source known to have strong lines. Typically only a few seconds (30) are required for detection of NH3 lines of sources like W3OH or TMC-1.

The observer should then check the system temperatures of all beams/polarizations using the GBTIDL command:

  • showtsys,Scan-Number - Display the system temperatures for all beams, polarizations and frequency bands.
  • getsigref,OnScan,OffScan - Display the sig-ref calibrated observations of your target source. The target source should be selected for strong lines in the frequency range of interest. Check all beams, polarizations and frequency bands for smooth spectral shapes. If the spectrometer is not setup properly use the CLEO spectrometer "reset-parameters" option to re-configure the spectrometer.

Pipeline with parameters tuned for Science requirements

The gbtpipeline automates many steps in the calibration and reduction steps.

To simplify the very first try of the Pipeline for NH3 1-1 and 2-2 line observations, we've created a script demoW51 to run through a complete observation reduction and imaging process.

The total reduction and imaging process takes approximately 10 minutes and yields a number of images. Two Integrated line images are produced and displayed. The pipeline must run on a 64 bit machine (eg arcturus.gb.nrao.edu, thales.gb.nrao.edu or euclid.gb.nrao.edu) To use this script in the Green Bank Linux environment type the following: 

mkdir /home/scratch/$USER/pipeline
cd /home/scratch/$USER/pipeline
cp /home/gbtpipeline/release/contrib/demoW51 .
./demoW51

The commands above create a scratch directory, then copy a demo script to that directory and finally executes the script. After completing the calibration and mapping, the script uses the casaviewer to display the integrated line intensity images and the temperature map.

The pipeline executable is located at

  • /opt/local/bin/gbtpipeline

Without arguments, the gbtpipeline starts up the appropriate version for the NRAO computer the observer is currently using.

The development version is also available as

  • /opt/local/bin/gbtpipeline-test

Pipeline parameter file options

The gbtpipeline command takes a large number of command line options. These values may also be input via a pipeline parameter file. To see the latest gbtpipeline options, run the command without any arguments.

Time sequence of KFPA On-Off Moon observations

MoonTemps11Oct23.png
Plot of Cal factors based on Lunar obs. at 18.5, 21.5, 23.7 and 25.5 GHz.

2011 October 23

Observations made during KFPA commissioning time on. Made a sequence of observations to confirm repeatability of observations. Three repetitions of observations of 23.7 GHz; Scans 1,2, 3,4 and 14,15. One observation each at 18.5, 21.5 and 25.5 GHz with all beams and polarizations: 

GBTIDL -> mooncalget,'TKFPA_83',1,2
...
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 165.8 162.6 161.0 166.5 161.6 161.7 211.7 218.9 157.8 190.4 212.2 283.3 150.6 136.6   23705.606  225.8   41.7    1
 1 151.4 150.6                                                                           22344.399  225.9   41.7    1

Calibration Factors
--gain-factors-left  1.046,1.077,1.073,0.819,1.099,0.817,1.152 
--gain-factors-right 1.066,1.042,1.073,0.792,0.911,0.612,1.269 
...
GBTIDL -> mooncalget,'TKFPA_83',3,4
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 165.6 162.5 159.9 166.2 161.1 159.2 210.2 217.8 158.5 190.1 212.2 285.1 150.7 136.2   23705.605  226.6   41.3    3
 1 150.8 150.6                                                                           22344.398  226.7   41.3    3

Calibration Factors
--gain-factors-left  1.046,1.083,1.075,0.824,1.092,0.816,1.149 
--gain-factors-right 1.066,1.042,1.087,0.795,0.911,0.607,1.272 
...
GBTIDL -> mooncalget,'TKFPA_83',10,11
...
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 146.0 144.1 159.8 156.4 150.1 139.6 239.2 240.8 166.8 196.4 202.7 220.5 201.1 373.9   18500.984  229.6   39.6   10
 1 161.5 160.2                                                                           19400.984  229.6   39.6   10
...
Calibration Factors
--gain-factors-left  1.294,1.182,1.258,0.790,1.132,0.932,0.939 
--gain-factors-right 1.310,1.208,1.352,0.784,0.961,0.856,0.505 
...
GBTIDL -> mooncalget,'TKFPA_83',12,13
...
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 159.2 143.1 163.4 149.0 156.0 148.8 191.0 198.7 171.2 179.9 198.9 234.8 171.4 177.6   21501.144  230.5   39.1   12
 1 153.3 154.2                                                                           22401.144  230.6   39.1   12
...
Calibration Factors
--gain-factors-left  1.089,1.061,1.112,0.908,1.012,0.872,1.011 
--gain-factors-right 1.211,1.164,1.165,0.872,0.963,0.738,0.976 
...
GBTIDL -> mooncalget,'TKFPA_83',14,15
...
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 163.9 161.0 159.4 163.4 160.1 159.0 209.1 216.5 156.9 187.9 210.6 281.9 149.4 134.9   23705.601  231.4   38.6   14
 1 149.5 149.1                                                                           22344.394  231.4   38.6   14
...
Calibration Factors
--gain-factors-left  1.045,1.075,1.070,0.819,1.092,0.814,1.147 
--gain-factors-right 1.064,1.048,1.078,0.791,0.912,0.608,1.270 
...
GBTIDL -> mooncalget,'TKFPA_83',16,17
...
#IF 1L    1R    2L    2R    3L    3R    4L    4R    5L    5R    6L    6R    7L    7R        MHz     Az(d)  El(d) Scan
 0 166.4 169.1 159.4 159.7 164.3 171.5 215.7 227.7 166.3 195.1 213.4 271.2 150.2  94.9   25501.356  232.1   38.1   16
 1 172.7 189.7                                                                           26401.356  232.2   38.1   16
...
Calibration Factors
--gain-factors-left  1.031,1.076,1.044,0.796,1.032,0.804,1.142 
--gain-factors-right 1.015,1.074,1.001,0.753,0.880,0.633,1.808

-- GlenLangston - 2011-09-07

Topic attachments
I Attachment Action Size Date Who Comment
MoonTemp11Oct23.txttxt MoonTemp11Oct23.txt manage 12 K 2011-11-03 - 10:48 GlenLangston Log of Moon Calibration obs
MoonTemps11Oct23.pngpng MoonTemps11Oct23.png manage 40 K 2011-11-03 - 10:57 GlenLangston Plot of Cal factors based on Lunar obs.
kfpaDataReduceGuide-11Dec01.pdfpdf kfpaDataReduceGuide-11Dec01.pdf manage 640 K 2011-12-07 - 10:49 GlenLangston Data Reduction guide
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