Pseudo GG Tau data set reduction

Pseudo GG Tau data set reduction

The Data Set

The data set was obtained in the following way:
  1. Select an approximately two hour period of one day of the Phase I data set of ALMA-Aips++ Test: (25-mar-1997, scans 7306 to 7429).
  2. Create from this data a 64-antenna Plateau de Bure data set:
  3. Convert the data set into ALMATI-FITS.
The list of data files is: 
-rw-r--r--    1 lucas    astro     217031040 Jun 27 09:26 phiii-64-1.fits
-rw-r--r--    1 lucas    astro    1663885440 Jun 27 09:29 phiii-64-2.fits
-rw-r--r--    1 lucas    astro    1663885440 Jun 27 09:31 phiii-64-3.fits
-rw-r--r--    1 lucas    astro     434059200 Jun 27 09:32 phiii-64-4.fits
-rw-r--r--    1 lucas    astro    1663885440 Jun 27 09:35 phiii-64-5.fits
-rw-r--r--    1 lucas    astro    1663885440 Jun 27 09:37 phiii-64-6.fits

Gildas Data Reduction Steps

  1. Fill the data into CLIC data files:


    Filling the data is done using the tifitstest program. This is a special version of tifits that has array dimensions extended to 64 antennas. The command is tifitstest @ all 64 256. The script is all.tifits. A file pipe.log is created that contains e.g.: 
        elapsed      total    user_cpu      total     sys_cpu      total ! all.tifits 64 256 
    -------      -----    --------      -----     -------      ----- ! 27-JUN-2003 08:39:47 
     732.38     732.38      318.35     318.55       57.80      58.01 ! end fits conversion
    Data files produced: 
    -rw-r--r--    1 lucas    astro    1695329280 Jun 27 10:42 phiii-64-1.ipb
-rw-r--r--    1 lucas    astro    1695329280 Jun 27 10:45 phiii-64-2.ipb
-rw-r--r--    1 lucas    astro    442266624 Jun 27 10:45 phiii-64-3.ipb
-rw-r--r--    1 lucas    astro    1695329280 Jun 27 10:48 phiii-64-4.ipb
-rw-r--r--    1 lucas    astro    1695329280 Jun 27 10:51 phiii-64-5.ipb
-rw-r--r--    1 lucas    astro    221137920 Jun 27 10:51 phiii-64-6.ipb

  2. Calibrate the data:


    Calibrating the data is done using the clictest program. This is a special version of clic that has array dimensions extended to 64 antennas. The command is clictest @ all 64 256. The script is all.clic. A file pipe.log is created that contains e.g.: 
        elapsed      total    user_cpu      total     sys_cpu      total ! all.clic 64 256 
    -------      -----    --------      -----     -------      ----- ! 27-JUN-2003 08:52:01 
     283.06     283.06       40.59      40.76       26.72      26.89 ! end create header file 64
      22.50     305.56       13.03      53.79        1.02      27.91 ! end select
     534.16     839.72      243.44     297.23       29.93      57.84 ! end monitor
    2544.09    3383.81     2326.59    2623.82        7.24      65.08 ! end rf
    1480.19    4864.00     1298.48    3922.30        9.80      74.88 ! end phase
     446.38    5310.38      374.81    4297.11        4.74      79.62 ! end flux 1
     502.50    5812.88      411.72    4708.83        6.30      85.92 ! end flux 2
    1047.66    6860.53      923.33    5632.16        6.57      92.49 ! end ampli
     152.97    7013.50       62.51    5694.67        9.45     101.94 ! end 3mm-table
     215.16    7228.66       90.24    5784.91       12.26     114.20 ! end 1mm-table
     159.19    7387.84       64.07    5848.98       10.36     124.56 ! end hco-table
     215.19    7603.03       87.75    5936.73       14.10     138.66 ! end co-table
    The data files produced are the calibrated uv tables: 
    -rw-r--r--    1 lucas    astro    12910592 Jun 27 13:01 1mm-64.uvt
-rw-r--r--    1 lucas    astro    12910592 Jun 27 13:02 3mm-64.uvt
-rw-r--r--    1 lucas    astro    97419264 Jun 27 12:59 co-64.uvt
-rw-r--r--    1 lucas    astro    97419264 Jun 27 12:59 hco-64.uvt
    The calibration steps are the following, all implemented in all.clic:

    1. create header


      A header file is created tha contains the data headers, that will be updated during the calibration process to include the calibration data. The data files themselves will not be modified. For this data set a single header file is created: 
      -rw-r--r--    1 lucas    astro    93529088 Jun 27 12:46 phiii-64.hpb

    2. select


      This is an automatic selection step where the useful scan numbers are selected, the calibrators counted, the strongest one selected as the passband calibrator.

    3. monitor


      In this step the choice is made on a scan by scan basis and antenna by antenna basis between using or not using the radiometric phase correction. The choice is based on comparing the corrected and raw amplitudes.
      The choices made are written into the header files.

    4. rf


      In this step the data on the passband calibrator are used to fit a polynomial antenna-based passband (polynomial parameter is intermediate frequency). This is particularly long for this data set as the passband calibrator as in fact the phase calibrator too, and it is observed at length.
      The polynomial coefficients are written into the headers for each scan (source and calibrators).

    5. phase


      In this step the data on the phase calibrators, with passband calibration applied, are used to fit a time-dependent phase calibration curve (cubic spline).
      1. This is done first for the 3mm data;
      2. The spline values for each 3mm scan is then stored in all 3mm data headers;
      3. The spline values for each 3mm scan are scaled to 1mm phases and stored in all 1mm scan headers;
      4. A residual 1mm phase spline curve is fitted into the 1mm phase data on calibrators, corrected for the observed 3mm phases scaled to 1mm;
      5. The residual 1mm phase spline curve values are then stored in all 1mm scan headers.


    6. flux


      In this step the amplitudes measured on calibrators are used to compute the flux of all calibrators, using one or more known fluxes as a reference. This is done in turn for 3mm and 1mm.
      The new fluxes are then stored in the headers for the calibrator scans.

    7. ampli


      In this step the amplitude measured on the amplitude calibrators (in this case the same as the phase calibrators), with passband and phase calibration applied, and divided by the source fluxes, are used to fit a time-dependent amplitude gain calibration curve (cubic spline).
      The ramplitude spline curve values are then stored in all scan headers.

    8. table


      In this step calibrated visibility tables are built, containing source visibility data, with all calibrations applied, optionally resampled to a new frequency grid.
      For this project 4 tables are built:
      1. 1mm table: all 1mm continuum (both side bands)
      2. 3mm table: all 3mm continuum (upper side bands)
      3. HCO+ table: 3mm line data (subband L02, 48 channels only)
      4. 13CO table: 1mm line data (subbands L04, 48 channels only)
      The output files are listed above.

  3. Create Images:


    Imaging is done using the graphic program. The command is GRAPHIC @ all 64 The script is all.graphic. A file pipe.log is created that contains e.g.: 
        elapsed      total    user_cpu      total     sys_cpu      total ! all.graphic 64 
    -------      -----    --------      -----     -------      ----- ! 27-JUN-2003 10:58:46 
      27.06      27.06       22.16      22.17        0.01       0.03 ! end uv_map co-64
       8.59      35.66        7.87      30.04        0.00       0.03 ! end clean co-64
       0.56      36.22        0.28      30.32        0.05       0.08 ! end plot co-64
      27.91      64.13       22.07      52.39        0.00       0.08 ! end uv_map hco-64
       9.75      73.88        9.06      61.45        0.01       0.09 ! end clean hco-64
       0.44      74.31        0.26      61.71        0.07       0.16 ! end plot hco-64
      71.84     146.16       63.62     125.33        0.00       0.16 ! end uv_map 1mm-64
       0.19     146.34        0.18     125.51        0.02       0.18 ! end clean 1mm-64
       0.09     146.44        0.05     125.56        0.01       0.19 ! end plot 1mm-64
      66.84     213.28       63.41     188.97        0.00       0.19 ! end uv_map 3mm-64
       0.19     213.47        0.18     189.15        0.00       0.19 ! end clean 3mm-64
       0.09     213.56        0.08     189.23        0.00       0.19 ! end plot 3mm-64
    -------      -----    --------      -----     -------      ----- ! 27-JUN-2003 11:02:20
    The data files produced are the cleaned images: 
    -rw-r--r--    1 lucas    astro      270336 Jun 27 13:01 1mm-64.lmv-clean
-rw-r--r--    1 lucas    astro      270336 Jun 27 13:02 3mm-64.lmv-clean
-rw-r--r--    1 lucas    astro    12591104 Jun 27 12:59 co-64.lmv-clean
-rw-r--r--    1 lucas    astro    12591104 Jun 27 13:00 hco-64.lmv-clean
    and image plot files: 
    -rw-r--r--    1 lucas    astro       41947 Jun 27 13:01 1mm-64.ps
-rw-r--r--    1 lucas    astro       85416 Jun 27 13:02 3mm-64.ps
-rw-r--r--    1 lucas    astro       75800 Jun 27 12:59 co-64.ps
-rw-r--r--    1 lucas    astro      104762 Jun 27 13:00 hco-64.ps
    The data processing steps are the following:

    1. Create `dirty' maps

      Non-default parameters are:
      name map_size map_cell weight_mode uv_cell
      hco-64 256 0.22 UNIFORM 7.5 2.8
      3mm-64 256 0.22 UNIFORM 7.5 0.9
      1mm-64 256 0.08 UNIFORM 7.5 3
      co-64 256 0.08 UNIFORM 7.5 12
      The same u,v coordinates are used for all channels in the line tables.

    2. Clean the maps

      Non-default parameters are:
      name niter gain method fres major minor angle
      3mm-64 2000 0.1 CLARK 0.02 1.99 1.25 20
      hco-64 500 0.2 CLARK 0.05 2.41 1.81 -180
      1mm-64 500 0.2 CLARK 0.05 0.85 0.59 -156
      co-64 500 0.2 CLARK 0.05 1.04 0.82 -178

    3. Plot the maps

      Plotting parameters are:
      name type first last size spacing
      3mm-64 lmv-clean 0 0 20 0.001
      hco-64 lmv-clean 11 35 20 0.025
      1mm-64 lmv-clean 0 0 10 0.007
      co-64 lmv-clean 7 31 10 0.050

    4. Final images:


      3mm-64.ps hco-64.ps 1mm-64.ps co-64.ps