  The RTDC Processing SMA Data 1.2 m Telescopes AST/RO Extra ## Testing Parallel Processing in CASA 5.3

Checking the output from tclean

CASA Parallelization Overview

Here I test the tclean task with CASA 5.3, comparing the output generated by using different numbers of cores. See the instructions here.

Following on from the previous tests we compare the average spectra. These are generated from a cube with 10% trimmed from the spectral axis, and a large circle, including most of the emission, extracted in the spatial plane.

Initial conclusions:
■ The statistics of the cleaned cubes continue to differ depending on the number of cores selected. The effect is marginal, but is more pronounced in some regions of the map.
■ Taking average spectra from a few pixels around a bright sources shows a max difference in a fitted peak of ~15% (between n=9 & n=3, towards the left hand peak in the plots below). Little to no difference towards a source in the right hand peak, and no difference at the brightest point in the map (peak integrated), or towards the top source (not included in the average spectra plots).
■ There may be a pattern in the emission recovered from the left hand peak. High average spectra : n=5,9,13, Low average spectra : n=3,7,11.

 Average spectra inside circle (see plot on right) n=9 - n=7 difference cube (contours: n=9 integrated)  n=9 / n=7 Full spectral cube Spectrally and spatially trimmed integrated image N(cores)=1 ```Pixel sum : 200384 Pixel mean : 0.000321857 Standard deviation : 0.0752239 Skewness : -5.10236 Kurtosis : -3.04114 Minimum pixel value : -127.512 At pixel : (1581, 1136, 86, 1) Maximum pixel value : 73.6167 At pixel : (43, 1425, 119, 1) Pixel median : -1.19904e-06 Total number of pixels : 622592000 Number of pixels used : 622585773 (100.0%) No. of pixels excluded : 6227 (0.0%) ``` ```Pixel sum : 9.97593e+08 Pixel mean : 243.553 Standard deviation : 6197.4 Skewness : 8.07061 Kurtosis : -2.97319 Minimum pixel value : -602863 At pixel : (1581, 1136) Maximum pixel value : 378257 At pixel : (1420, 1509) Pixel median : -0.109765 Total number of pixels : 4096000 Number of pixels used : 4096000 (100.0%) No. of pixels excluded : 0 (0.0%) ``` N(cores)=5 ```Pixel sum : 274325 Pixel mean : 0.000440623 Standard deviation : 0.0752474 Skewness : 7.90136 Kurtosis : -3.07584 Minimum pixel value : -75.0906 At pixel : (843, 2176, 59, 1) Maximum pixel value : 104.372 At pixel : (1576, 1141, 137, 1) Pixel median : -5.03141e-07 Total number of pixels : 622592000 Number of pixels used : 622585810 (100.0%) No. of pixels excluded : 6190 (0.0%) ``` ```Pixel sum : 1.07687e+09 Pixel mean : 1378.64 Standard deviation : 10106.6 Skewness : 2.90791 Kurtosis : -3.35131 Minimum pixel value : -29732.8 At pixel : (775, 1280) Maximum pixel value : 137202 At pixel : (888, 1221) Pixel median : 132.339 Total number of pixels : 4096000 Number of pixels used : 781109 (19.1%) No. of pixels excluded : 3314891 (80.9%) ``` N(cores)=7 ```Pixel sum : 275571 Pixel mean : 0.000442623 Standard deviation : 0.0752186 Skewness : 2.48467 Kurtosis : -3.04699 Minimum pixel value : -65.8146 At pixel : (803, 628, 22, 1) Maximum pixel value : 71.1451 At pixel : (47, 1749, 8, 1) Pixel median : -5.18267e-07 Total number of pixels : 622592000 Number of pixels used : 622585899 (100.0%) No. of pixels excluded : 6101 (0.0%) ``` ```Pixel sum : 1.08106e+09 Pixel mean : 1384.01 Standard deviation : 10103.8 Skewness : 2.95316 Kurtosis : -3.17464 Minimum pixel value : -28712.3 At pixel : (1075, 988) Maximum pixel value : 137438 At pixel : (888, 1221) Pixel median : 117.755 Total number of pixels : 4096000 Number of pixels used : 781109 (19.1%) No. of pixels excluded : 3314891 (80.9%) ``` N(cores)=9 ```Pixel sum : 306768 Pixel mean : 0.000492732 Standard deviation : 0.0752929 Skewness : 7.33751 Kurtosis : -2.91486 Minimum pixel value : -66.5957 At pixel : (87, 1170, 53, 1) Maximum pixel value : 86.3653 At pixel : (44, 1436, 51, 1) Pixel median : -2.41406e-07 Total number of pixels : 622592000 Number of pixels used : 622585689 (100.0%) No. of pixels excluded : 6311 (0.0%) ``` ```Pixel sum : 1.22334e+09 Pixel mean : 1566.16 Standard deviation : 10145.5 Skewness : 2.97839 Kurtosis : -3.23465 Minimum pixel value : -29447.3 At pixel : (1075, 988) Maximum pixel value : 138061 At pixel : (888, 1221) Pixel median : 244.476 Total number of pixels : 4096000 Number of pixels used : 781109 (19.1%) No. of pixels excluded : 3314891 (80.9%) ```

CENTER FOR ASTROPHYSICS | HARVARD & SMITHSONIAN
60 GARDEN STREET, CAMBRIDGE, MA 02138