Australia Telescope National Facility

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Execution

When executed without command line arguments, Pieflag will print out a help message, which pretty much covers everything you can do with it. A copy is included below. I strongly encourage you to specify the reference channel using the "-goodch" command line option. Otherwise, Pieflag will take the centre channel, which may not be a good choice.

pieflag.py filename [options]

filename	is required. Unless otherwise specified, it must be a Miriad data directory.
General options:
-filename name	name of Miriad data file for which the flags shall be prepared. Defaults to uvlist file
-uvlist	first command-line argument already is a uvlist file. Default is that it's a Miriad data directory and a uvlist file needs to be created
-test n m o	process only data on baseline n m, and channel o (assuming channel o is bad). Allows to adjust flag finding parameters more quickly as fewer data need to be processed. Specify a good channel using the -goodch option
-stokes x,y[,z,..]	specify which stokes parameters to read and analyse (x) and which polarizations to flag (y,z,...). For example, one can read and analyse rr and use the results to flag both rr and ll by specifying -stokes rr,rr,ll. The possible values are the same as for Miriad's "stokes" keyword, defaults to read Stokes I and to flag all polarizations
-v	print flagging thresholds, report on progress, print summary
-vv	print lots (you don't want this, believe me)
Flag finding options:
-goodch n	number of a good (RFI-free) channel to which the other channels are to be compared, defaults to centre of band
-cutoff n	multiples of median of difference to median in data, above which data are suspicious. Will be multiplied by two to obtain a threshold above which data are certainly bad, defaults to 7
-noamp	don't flag based on amplitude rms
-gap	time in seconds which defines a scan gap (source changes also define scans), defaults to 300
-rmscut	factor by which the RFI-free channel's scan-by-scan rms is to be multiplied and above which data is considered bad, defaults to 3
-norms	don't flag based on amplitude rms calculated on scan-by-scan basis
Flag extension options:
-long n	width of running sum window in seconds in which to calculate fraction of flagged visibilities. 1200 is reasonable for weak sources, 600 for calibrator observations, defaults to 1200
-thres n	raction of maximum of running sum, defines threshold above which data are deemed bad in search for large clusters of bad points, defaults to 0.15
-noshort	don't flag short (60s) sections around bad points. This effectively turns off amplitude-based flagging because amplitude-based flagging does not generate flags directly
-nolong	don't search for larger clusters of points
Plotting options:
(press h in plotting window for a list of shortcuts)
-noplot	skip plotting and interactive flagging
-xy xmin,xmax,ymin,ymax	define initial plotting range

Next: Tips Up: Usage Previous: General remarks