Usage of getfwhm
Return to directory of Todd's CASA extensions
Directly estimate the actual FWHM of the CASA image provided, with no assumption
about shape except that the function has a well defined peak and is approximately
azimuthally symmetric. It takes the average of two median values: the median radius
of the first 5 points above half-power, and the first 5 points below half-power. Algorithm riginally written
by Brian Mason. For an alternative algorithm, see also
getfwhm2. To operate on arrays of data, see
findFWHM.
Usage:
au.getfwhm(imgfile, pkXmin='min', pkXmax='max', pkYmin='min', pkYmax='max',
pixelSize=None, axis3channel=0, axis4channel=0, plotfile=None, ignoreIdenticalZeros=True,
plotrange=[0,0,0,0], gaussian=None, showlog=False, plotrange2=[0,0,0,0])
- INPUT:
- OPTIONAL INPUT
- pk{X,Y}{min,max} - pixel coordinate range (integers) within which to search for peak and FWHM. so long as this region contains the peak and the half max point you should get reasonable results. (default is to consider all pixels)
- pixelSize - if None, use value from image header (supports deg or rad units)
- axis3channel - which channel of the cube to use (if naxis>2)
- axis4channel - which channel of the cube to use (if naxis>3)
- plotfile - if True, or a string, then write a png file
- ignoreIdenticalZeros -- if True, then filter out pixels with exactly 0 intensity
- plotrange: [xmin,xmax,ymin,ymax]
- gaussian: the FWHM of a Gaussian profile to overlay in magenta
- showlog: if True, show the log of the intensity in a second panel
- plotrange2: same as plotrange but for the second panel
- RETURN:
- full width half max in arcseconds (or in units of pixels if pixelSize is set to 1.0)
Example:
CASA <3>: au.getfwhm('uid___A002_X65c1ab_Xd8d_APC-DV18-V-USB-beam_square',plotfile='getfwhm.png',plotrange=[0,60,0,1.05])
Got pixelSize = 2.484117 arcsec
Max found at pixel 512.0 512.0
peak = 110201360.0
Plot saved in getfwhm.png
Out[53]: 17.913220347188155
--
ToddHunter - 2013-08-26
- getfwhm.png: