Does anybody out there understand how DBCON flags your data? The help file is being less than transparent. DBCON seems to copy over all the FG tables from the first image you give it to the DBCON'd file, but does not appear to copy FG tables from the second image.
There is this note in the help file:
"Also, any CL, FG, TY, WX, IM, MC, PC, AT, CT, OB, or GC tables with version=1 will have their source numbers translated and appended to the end of the corresponding table (if any) from the first file."
So, let's say I have 13 flag tables for Image1 and 6 flag tables for Image2 (which happens a lot with the new crazy FG table creation scheme). Does this mean FG #1 for Image2 gets appended to FG tables 1-13 from Image1? And then in the futere, I will be apply a combination of FG#1 to Image1 and FG #13 to Image2? That's kinda dumb...
Wednesday, July 16, 2008
How does DBCON deal with flagging?
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4 comments:
DBCON is very stupid about copying tables over. As you note the documentation only copies over the tables from the first time. The rest of the tables have to be copied over separately using TACOP. This isn't very helpful since AIPS only uses one flag table at a time. I don't know of a way to concatenate the FLAG files. When I did this it was for SN tables and the SN tables are automatically concatenated in CLCAL.
Also I think that the note in the help file just copies over the source numbers not the actual data. That way you know what sources are in the file, but the calibration data isn't copied over.
Yes, for FG tables maybe it is a bit different? I have taken to making sure that both of my input images to DBCON only have one FG table each-- then it concatenates them properly. This is annoying-- requiring me to EXTDEST all the earlier tables and then TACOP the most recent to #1 and then delete the most recent-- but at least then I understand what is going on!
I believe you can concatenate flag tables, as I accidentally discovered. If you use TABED, it can add the rows of the table you're editing to the end of an existing table. There's a little gem in the help file:
"If the output table is not the same as
the input table then the new entries are appended to the end of the
table."
I'm not sure if you can use TABED to just copy a table without doing any modifications, but it's worth a shot if you really need to concatenate some flag tables.
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