Renaming a Field: Difference between revisions

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Sometimes sources are named the "wrong" thing in the original data set, and it would be nice to change the field name. Such as in this case I just encountered:
Sometimes sources are named the "wrong" thing in the original data set, and it would be nice to change the field name. Such as in this case I just encountered:


The flux calibrator in a data set was named "J1331+3030'. [[Setjy]] only recognizes three names for this source ('3C286', '1328+307', and '1331+305')---none of which match the field name in the dataset. So, if we try to run [[setjy]] on this source, we'll see that the flux density is set to 1 Jy, which is incorrect.
The flux calibrator in a data set was named "J1331+3030'. {{Setjy}} only recognizes three names for this source ('3C286', '1328+307', and '1331+305')---none of which match the field name in the dataset. So, if we try to run {{setjy}} on this source, we'll see that the flux density is set to 1 Jy, which is incorrect.
<pre>
<pre>
2010-02-10 23:35:30 INFO setjy ##########################################
2010-02-10 23:35:30 INFO setjy ##########################################
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2010-02-10 23:35:31 INFO setjy ##########################################
2010-02-10 23:35:31 INFO setjy ##########################################
</pre>
</pre>
In order for [[setjy]] to work properly, we need to change the name of our flux calibrator. We can do this in two ways, the first using [[tb | table utilities]]:
In order for {{setjy}} to work properly, we need to change the name of our flux calibrator. We can do this in two ways, the first using [[tb | table utilities]]:
<pre>
<pre>
tb.open('leotest.ms/FIELD',nomodify=False)
tb.open('leotest.ms/FIELD',nomodify=False)
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tb.close()
tb.close()
</pre>
</pre>
The second is a bit more user-friendly, with the task [[browsetable]]:
The second is a bit more user-friendly, with the task {{browsetable}}:
<pre>
<pre>
#  browsetable :: Browse a table (MS, calibration table, image)
#  browsetable :: Browse a table (MS, calibration table, image)
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We should be all set! Quit out of [[browsetable]] by going to the File Menu >> Exit. Double-check the edits using [[listobs]].
We should be all set! Quit out of {{browsetable}} by going to the File Menu >> Exit. Double-check the edits using {{listobs}}.


And, if we run [[setjy]] again:
And, if we run {{setjy}} again:
<pre>
<pre>
2010-02-11 00:31:42 INFO setjy ##########################################
2010-02-11 00:31:42 INFO setjy ##########################################

Revision as of 17:54, 7 June 2010

Hints, Tips, and Tricks

Sometimes sources are named the "wrong" thing in the original data set, and it would be nice to change the field name. Such as in this case I just encountered:

The flux calibrator in a data set was named "J1331+3030'. setjy only recognizes three names for this source ('3C286', '1328+307', and '1331+305')---none of which match the field name in the dataset. So, if we try to run setjy on this source, we'll see that the flux density is set to 1 Jy, which is incorrect.

2010-02-10 23:35:30 INFO setjy	##########################################
2010-02-10 23:35:30 INFO setjy	##### Begin Task: setjy              #####
2010-02-10 23:35:30 INFO  	setjy::::casa
2010-02-10 23:35:30 INFO setjy	  J1331+3030  spwid=  0  [I=1, Q=0, U=0, V=0] Jy, (default)
2010-02-10 23:35:30 INFO setjy	Selecting data
2010-02-10 23:35:30 INFO setjy	Selected 4818 out of 70290 visibilities.
2010-02-10 23:35:30 INFO setjy	Fourier transforming: replacing MODEL_DATA column
2010-02-10 23:35:30 INFO setjy	Processing after subtracting componentlist 
/export/home/rso-lchomiuk/test/Leo/leotest.ms.J1331+3030.spw0.tempcl
2010-02-10 23:35:30 INFO setjy	Performing interferometric gridding with convolution function SF
2010-02-10 23:35:31 INFO  	setjy::::casa
2010-02-10 23:35:31 INFO setjy	##### End Task: setjy                #####
2010-02-10 23:35:31 INFO setjy	##########################################

In order for setjy to work properly, we need to change the name of our flux calibrator. We can do this in two ways, the first using table utilities:

tb.open('leotest.ms/FIELD',nomodify=False)
st=tb.selectrows(4)
st.putcol('NAME','1331+305')
st.done()
tb.close()

The second is a bit more user-friendly, with the task browsetable:

#  browsetable :: Browse a table (MS, calibration table, image)
tablename           = 'leotest.ms'      #  Name of input table
async               =      False        #  If true the taskname must be started using browsetable(...)

This will bring up a GUI that looks like this:

The browsetable GUI.

Click on 'Table Keywords', one of the tabs at the screen's left. We'll then see a window that looks like this:

Select a table keyword.

Double click on 'FIELD'. This will take us to a screen that looks like this:

Edit field names here.

Enter 'edit table' mode by clicking on the icon that looks like this: 'Edit table' icon. Double click on the cells that need editing (in this case, those that read 'J1331+3030') and type the corrected name.


We should be all set! Quit out of browsetable by going to the File Menu >> Exit. Double-check the edits using listobs.

And, if we run setjy again:

2010-02-11 00:31:42 INFO setjy	##########################################
2010-02-11 00:31:42 INFO setjy	##### Begin Task: setjy              #####
2010-02-11 00:31:42 INFO  	setjy::::casa
2010-02-11 00:31:42 INFO setjy	    1331+305  spwid=  0  [I=14.75, Q=0, U=0, V=0] Jy, (Perley-Taylor 99)
2010-02-11 00:31:42 INFO setjy	Selecting data
2010-02-11 00:31:42 INFO setjy	Selected 4818 out of 70290 visibilities.
2010-02-11 00:31:42 INFO setjy	Fourier transforming: replacing MODEL_DATA column
2010-02-11 00:31:42 INFO setjy	Processing after subtracting componentlist 
/export/home/rso-lchomiuk/test/Leo/leotest.ms.1331+305.spw0.tempcl
2010-02-11 00:31:42 INFO setjy	Performing interferometric gridding with convolution function SF
2010-02-11 00:31:43 INFO  	setjy::::casa
2010-02-11 00:31:43 INFO setjy	##### End Task: setjy                #####
2010-02-11 00:31:43 INFO setjy	##########################################

14.75 Jy...much better.

Last checked on CASA Version 3.0.0 (r9860).

--Laura Chomiuk 00:10, 11 February 2010 (UTC)