Difference between revisions of "EVLA 6cmWideband Tutorial SN2010FZ"

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== Importing your EVLA data from SDM ==
 
== Importing your EVLA data from SDM ==
  
For the purposes of this tutorial, we assume that the SDM is resident on disk, in this case at the location
+
For the purposes of this tutorial, we assume that the SDM is resident on disk, in this case at the location:
<tt>/lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065</tt>.  
+
<pre>/lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065</pre>   
 
Use the actual location of your data when you carry out the commands.
 
Use the actual location of your data when you carry out the commands.
  
Line 168: Line 168:
  
 
If you are starting from the filled MS, you can find this at the AOC at:
 
If you are starting from the filled MS, you can find this at the AOC at:
<tt>/lustre/smyers/AS1015/SN2010FZ_filled.ms<tt>
+
<pre>/lustre/smyers/AS1015/SN2010FZ_filled.ms</pre>
 +
Again, use the actual location of this file for your system.
  
 
NOTE: the following step will not work in Version 3.2.1 (you will get a blank plot) but should in later versions).
 
NOTE: the following step will not work in Version 3.2.1 (you will get a blank plot) but should in later versions).
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If you are starting from the pre-flagged averaged split MS, you can find this at the AOC at:
 
If you are starting from the pre-flagged averaged split MS, you can find this at the AOC at:
<tt>/lustre/smyers/AS1015/SN2010FZ_filled10s.ms<tt>
+
<pre>/lustre/smyers/AS1015/SN2010FZ_filled10s.ms</pre>
  
 
We use {{listobs}} to summarize our new MS:
 
We use {{listobs}} to summarize our new MS:

Revision as of 13:47, 25 August 2011

Overview

This article describes the calibration and imaging of a single-pointing 6cm EVLA wideband continuum dataset on the galaxy NGC2967 (UGC5180) which was the location of the supernova candidate SN2010FZ. No supernova was detected in this observation, but the galactic continuum emission from this face-on spiral is adequately imaged. The data were taken in RSRO mode, with 1024 MHz of bandwidth in each of two widely spaced basebands (comprised each of 8 128 MHz spectral windows), spanning 4.5 to 7.5 GHz. We will use wideband imaging techniques in this tutorial.

This is a more advanced tutorial, and if you are a relative novice (and particularly for EVLA continuum calibration and imaging), it is strongly recommended that you start with the EVLA Continuum Tutorial 3C391 before tackling this dataset. We will not include basic information on CASA processing in this tutorial.

CASA Versions

This tutorial was written for the CASA Version 3.2.1 (release r15198 26 May 2011).

Obtaining the Data

The scheduling block (SB) processed appears in the EVLA archive under program AS1015 as AS1015_sb1658169_1.55388.89474846065 and was run on 2010-07-11 from 21:28 to 22:28 UT (size 37.74GB).

For the purposes of this tutorial, we have provided the raw SDM data (as would be extracted from the archive) as well as measurement sets created by filling the data (with the importevla task) and upon time-averaging to 10s (after application of the online flags).

To start your tutorial, depending on which dataset you start with, proceed to:

  • To start with the raw SDM data: Start with the section below titled "Importing your EVLA data from SDM". This is where you would start if you were reducing data from the archive.
  • To start with the raw filled MS: Start with the section below titled "Application of Online Flags and Averaging your MS".
  • To start with the flagged and averaged MS: Start with the section below titled "Examining and Flagging your Averaged MS".

Importing your EVLA data from SDM

For the purposes of this tutorial, we assume that the SDM is resident on disk, in this case at the location:

/lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065

Use the actual location of your data when you carry out the commands.

The listsdm task will print out a summary of the scans, fields, spectral windows, and antennas present in your SDM.

# In CASA
listsdm('/lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065')

In the logger you should see:

================================================================================
   SDM File: /lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065
================================================================================
   Observer: Dr. Alicia M. Soderberg
   Facility: EVLA, D-configuration
      Observed from 2010/07/11/21:28:28.41 to 2010/07/11/22:28:17.73 (UTC)
      Total integration time = 3589.32 seconds (1.00 hours)
 
Scan listing:
  Timerange (UTC)           Scan FldID  FieldName       SpwIDs         Intent(s)
  21:28:28.41 - 21:29:27.40    1     0  J0925+0019      [0, 1]  CALIBRATE_PHASE
  21:29:27.40 - 21:30:57.16    2     0  J0925+0019      [0, 1]  CALIBRATE_PHASE
  21:30:57.16 - 21:32:26.91    3     0  J0925+0019      [0, 1]  CALIBRATE_PHASE
  21:32:26.91 - 21:33:56.67    4     0  J0925+0019      [0, 1]  CALIBRATE_PHASE
  21:33:56.67 - 21:34:56.50    5     0  J0925+0019      [0, 1]  CALIBRATE_PHASE
  21:34:56.50 - 21:35:56.34    6     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  21:35:56.34 - 21:37:26.09    7     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  21:37:26.09 - 21:38:25.93    8     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  21:38:25.93 - 21:39:55.68    9     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:39:55.68 - 21:41:25.44   10     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:41:25.44 - 21:42:55.19   11     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:42:55.19 - 21:44:24.94   12     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:44:24.94 - 21:45:54.70   13     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:45:54.70 - 21:47:24.45   14     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:47:24.45 - 21:47:54.37   15     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:47:54.37 - 21:49:24.12   16     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  21:49:24.12 - 21:50:53.88   17     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:50:53.88 - 21:52:23.63   18     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:52:23.63 - 21:53:53.39   19     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:53:53.39 - 21:55:23.14   20     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:55:23.14 - 21:56:52.89   21     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:56:52.89 - 21:58:22.65   22     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:58:22.65 - 21:58:52.57   23     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  21:58:52.57 - 22:00:22.32   24     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  22:00:22.32 - 22:01:52.07   25     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:01:52.07 - 22:03:21.83   26     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:03:21.83 - 22:04:51.58   27     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:04:51.58 - 22:06:21.34   28     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:06:21.34 - 22:07:51.09   29     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:07:51.09 - 22:09:20.85   30     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:09:20.85 - 22:09:50.76   31     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:09:50.76 - 22:11:20.52   32     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  22:11:20.52 - 22:12:50.27   33     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:12:50.27 - 22:14:20.02   34     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:14:20.02 - 22:15:49.78   35     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:15:49.78 - 22:17:19.53   36     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:17:19.53 - 22:18:49.29   37     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:18:49.29 - 22:20:19.04   38     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:20:19.04 - 22:20:48.96   39     1  SN2010FZ        [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  OBSERVE_TARGET
  22:20:48.96 - 22:22:18.71   40     0  J0925+0019      [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_PHASE
  22:22:18.71 - 22:23:48.47   41     2  3C286           [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_BANDPASS CALIBRATE_AMPLI
  22:23:48.47 - 22:25:18.22   42     2  3C286           [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_BANDPASS CALIBRATE_AMPLI
  22:25:18.22 - 22:26:47.98   43     2  3C286           [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_BANDPASS CALIBRATE_AMPLI
  22:26:47.98 - 22:28:17.73   44     2  3C286           [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]  CALIBRATE_BANDPASS CALIBRATE_AMPLI
 
Spectral window information:
  SpwID  #Chans  Ch0(MHz)  ChWidth(kHz) TotBW(MHz)  Baseband
  0      64      7686.0    2000.0       128.0       BB_4    
  1      64      7836.0    2000.0       128.0       BB_8    
  2      64      4488.0    2000.0       128.0       BB_4    
  3      64      4616.0    2000.0       128.0       BB_4    
  4      64      4744.0    2000.0       128.0       BB_4    
  5      64      4872.0    2000.0       128.0       BB_4    
  6      64      5000.0    2000.0       128.0       BB_4    
  7      64      5128.0    2000.0       128.0       BB_4    
  8      64      5256.0    2000.0       128.0       BB_4    
  9      64      5384.0    2000.0       128.0       BB_4    
  10     64      6488.0    2000.0       128.0       BB_8    
  11     64      6616.0    2000.0       128.0       BB_8    
  12     64      6744.0    2000.0       128.0       BB_8    
  13     64      6872.0    2000.0       128.0       BB_8    
  14     64      7000.0    2000.0       128.0       BB_8    
  15     64      7128.0    2000.0       128.0       BB_8    
  16     64      7256.0    2000.0       128.0       BB_8    
  17     64      7384.0    2000.0       128.0       BB_8    
 
Field information:
  FldID  Code   Name             RA            Dec             SrcID
  0      D      J0925+0019       09:25:07.82   +000.19.13.933  0    
  1      NONE   SN2010FZ         09:42:04.77   +000.19.51.000  1    
  2      K      3C286            13:31:08.29   +030.30.32.959  2    
 
Antennas (27):
  ID    Name   Station   Diam.(m)  Lat.          Long.
  0     ea01   W09       25.0      +000.00.00.0  +000.00.00.0 
  1     ea02   E02       25.0      +033.53.51.0  -107.37.25.2 
  2     ea03   E09       25.0      +033.54.01.1  -107.37.04.4 
  3     ea04   W01       25.0      +033.53.53.6  -107.36.45.1 
  4     ea05   W08       25.0      +033.54.00.5  -107.37.05.9 
  5     ea06   N06       25.0      +033.53.53.0  -107.37.21.6 
  6     ea08   N01       25.0      +033.54.10.3  -107.37.06.9 
  7     ea09   E06       25.0      +033.54.01.8  -107.37.06.0 
  8     ea10   N03       25.0      +033.53.57.7  -107.36.55.6 
  9     ea11   E04       25.0      +033.54.04.8  -107.37.06.3 
  10    ea12   E08       25.0      +033.53.59.7  -107.37.00.8 
  11    ea13   N07       25.0      +033.53.55.1  -107.36.48.9 
  12    ea14   E05       25.0      +033.54.12.9  -107.37.07.2 
  13    ea15   W06       25.0      +033.53.58.8  -107.36.58.4 
  14    ea16   W02       25.0      +033.53.56.4  -107.37.15.6 
  15    ea17   W07       25.0      +033.54.00.9  -107.37.07.5 
  16    ea18   N09       25.0      +033.53.54.8  -107.37.18.4 
  17    ea19   W04       25.0      +033.54.19.0  -107.37.07.8 
  18    ea20   N05       25.0      +033.53.59.1  -107.37.10.8 
  19    ea21   E01       25.0      +033.54.08.0  -107.37.06.7 
  20    ea22   N04       25.0      +033.53.59.2  -107.37.05.7 
  21    ea23   E07       25.0      +033.54.06.1  -107.37.06.5 
  22    ea24   W05       25.0      +033.53.56.5  -107.36.52.4 
  23    ea25   N02       25.0      +033.53.57.8  -107.37.13.0 
  24    ea26   W03       25.0      +033.54.03.5  -107.37.06.2 
  25    ea27   E03       25.0      +033.54.00.1  -107.37.08.9 
  26    ea28   N08       25.0      +033.54.00.5  -107.37.02.8 

The C-band data of interest is contained in scans 6-44 and spans spectral windows 2 to 17.

We use the importevla task to convert the SDM dataset from the archive to a CASA Measurement Set (MS).

# In CASA
importevla(asdm='/lustre/smyers/AS1015/AS1015_sb1658169_1.55388.89474846065', \
           vis='SN2010FZ_filled.ms',online=True,flagzero=True, \
           shadow=True,applyflags=False,tbuff=1.5,flagbackup=False)

Here we had the task create (but not apply) the online flagging commands, plus flags for zero-clipping and shadowing. The timeranges for the online flags were extended by 1.5sec (the integration time was 1sec) to account for some timing mismatches present in the EVLA data at this time. These online flags indicated times where the antennas were not on source (e.g. slewing) or had other detectable faults. The created flagging commands will be stored in the FLAG_CMD MS table and can be applied later. Note that if you set applyflags=True here then after filling the task will go ahead and apply the flags for you.

For the purposes of this exercise, in order to save time and disk space, we have turned off the automatic creation of flag column backups by setting flagbackup=False. If we make a mistake and need to recover flags then we will have to rerun all previous commands. We recommend that for real data processing that you leave the default value flagbackup=True in this and subsequent tasks.

You now have a MS called SN2010FZ_filled.ms in your working area. This should be 37GB like the SDM.

Application of Online Flags and Averaging your MS

If you are starting from the filled MS, you can find this at the AOC at:

/lustre/smyers/AS1015/SN2010FZ_filled.ms

Again, use the actual location of this file for your system.

NOTE: the following step will not work in Version 3.2.1 (you will get a blank plot) but should in later versions). You can examine the commands stored in the FLAG_CMD table using flagcmd.

# In CASA
flagcmd(vis='SN2010FZ_filled.ms',flagmode='table',optype='plot')

This will bring up a matplotlib plotter. You can have it plot to a PNG file instead:

# In CASA
flagcmd(vis='SN2010FZ_filled.ms',flagmode='table',optype='plot',outfile='plotSN2010FZ_flagcmd.png')

To apply the flags also use flagcmd:

# In CASA
flagcmd(vis='SN2010FZ_filled.ms',flagmode='table',optype='apply',flagbackup=False)

This can take a while for our 37GB dataset. It took 20min on my workstation.

With the known bad data flagged, we can now split out the data we want and also average down in time to make a smaller MS. For D-configuration (max baselines 1km) we can safely average to 3s or even 10s to reduce dataset size:

# In CASA
split(vis='SN2010FZ_filled.ms',outputvis='SN2010FZ_filled10s.ms',datacolumn='data',timebin='10s')

This can also take a while for our 37GB dataset. It took 20min on my workstation.

You now have a MS called SN2010FZ_filled10s.ms in your working area.

Examining and Flagging your Averaged MS

If you are starting from the pre-flagged averaged split MS, you can find this at the AOC at:

/lustre/smyers/AS1015/SN2010FZ_filled10s.ms

We use listobs to summarize our new MS:

# In CASA
listobs('SN2010FZ_filled10s.ms')

Scan 6 is a dummy scan so we will use scans 7 to 44 when we process our data.

To plot up the antenna positions in the array:

# In CASA
plotants('SN2010FZ_filled10s.ms')

NOTE: if after this point or any other you get table locks, use clearstat to clear them:

# In CASA
clearstat

Now we examine the MS looking for bad data to flag. The useful spw are 2~17. To get an idea of the data layout, plot a single baseline/channel versus time. We will use plotms - this will bring up an interactive GUI that will display 2-D Y vs.X style line plots:

# In CASA
plotms(vis='SN2010FZ_filled10s.ms',field='',spw='2~17:31~31',antenna='ea01&ea02',correlation='RR,LL',xaxis='time',yaxis='amp')