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Image Analysis with CASA - ESO

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<strong>CASA</strong>> imgstat = imstat()<br />

imgstat is now defined as<br />

a Python dictionary,<br />

containing all keys listed on the right.<br />

Access: imgstat['KEY'][AXIS]<br />

<strong>CASA</strong>>rms=(imgstat['rms'][0])<br />

print '>> rms: '+str(rms)<br />

peak=(imgstat['max'][0])<br />

print '>> Peak: '+str(peak)<br />

print '>> Dynamic range: '+str(peak/rms)<br />

KEYS<br />

blc ­ absolute PIXEL coordinate of the bottom left corner of<br />

the bounding box surrounding the selected region<br />

blcf ­ Same as blc, but uses WORLD coordinates instead of pixels<br />

trc ­ the absolute PIXEL coordinate of the top right corner<br />

of the bounding box surrounding the selected region<br />

trcf ­ Same as trc, but uses WORLD coordinates instead of pixels<br />

flux ­ the integrated flux density if the beam is defined and<br />

the if brightness units are $Jy/beam$<br />

npts ­ the number of unmasked points used<br />

max ­ the maximum pixel value<br />

min ­ minimum pixel value<br />

maxpos ­ absolute PIXEL coordinate of maximum pixel value<br />

maxposf ­ Same as maxpos, but uses WORLD coordinates instead of pixels<br />

minpos ­ absolute pixel coordinate of minimum pixel value<br />

minposf ­ Same as minpos, but uses WORLD coordinates instead of pixels<br />

sum ­ the sum of the pixel values: $\sum I_i$<br />

sumsq ­ the sum of the squares of the pixel values: $\sum I_i^2$<br />

mean ­ the mean of pixel values:<br />

$ar{I} = \sum I_i / n$<br />

sigma ­ the standard deviation about the mean:<br />

$\sigma^2 = (\sum I_i ­ar{I})^2 / (n­1)$<br />

rms ­ the root mean square:<br />

$\sqrt {\sum I_i^2 / n}$<br />

median ­ the median pixel value (if robust=T)<br />

medabsdevmed ­ the median of the absolute deviations from the<br />

median (if robust=T)<br />

quartile ­ the inter­quartile range (if robust=T). Find the points<br />

which are 25% largest and 75% largest (the median is<br />

50% largest), find their difference and divide that<br />

difference by 2.<br />

14

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