[daip] AIPS task SAD

[Kunal]

That worked! Thanks, Eric.

- Kunal.


On 03/19/2014 09:12 AM, Eric Greisen wrote:
> Kunal wrote:
>> Hi Eric!
>> I need help with SAD. I'm trying to find point sources in a EVLA 
>> S-band FLATN mosaic image. There are at least 3 sources in the image 
>> with signal-to-noise ratio greater than 100, but SAD finds no 
>> sources. I've included the output from SAD below.
>>
>> I'm using default parameters of SAD except for:
>> taskSAD.ngauss   = 40000
>> taskSAD.doall    = 1
>> taskSAD.dparm(1)  = 5
>> taskSAD.dparm(7)  = 1
>> taskSAD.dparm(9)  = 2
>>
>> I have used these input parameters to successfully sources in many 
>> other images, but for this particular image, I'm having trouble.
>>
>> Thanks in advance!
>> - Kunal.
>>
>> P.S.
>> 1) The image is located at 
>> /lustre/kmooley/projects/JVLACOSMOS/concat_R1/fits/fits/temp/M_X1_Y4.fits.
>>
>> 2) Output from SAD:
>>
>> SAD  1: Task SAD    (release of 31DEC13) begins
>> SAD  1: Create ABC         .RESID .   1 (MA)  on disk  1  cno 3
>> SAD  1: Fit to histogram gives RMS = 5.031E-06
>> SAD  1: Setting Search limit at 3.0 x RMS of 0.0000
>> SAD  1: Looking for up to40000 sources in subfield:
>> SAD  1: BLC:       1.      1.      1.      1.      1.      1. 1.
>> SAD  1: TRC:    4096.   4096.      1.      1.      1.      1. 1.
>> SAD  1: Using Clean beam   1.00001   1.00001    0.00 from image header
>> SAD  1: Searching down to   0.000015 (JY/BEAM )  pass 1
>> SAD  1: Found  12536 Islands in pass 1
>> SAD  1: No convergence for island 570 Box   3168.   726.  3188. 767.
>> SAD  1: No convergence for island6440 Box   1542.  2779.  1661. 2905.
>> SAD  1: No convergence for island2412 Box     93.  1696.   144. 1727.
>> SAD  1: No convergence for island3847 Box   1226.  2136.  1302. 2205.
>> SAD  1: No convergence for island**** Box   3016.  4085.  3027. 4096.
>> SAD  1: No convergence for island7594 Box    593.  3141.   610. 3165.
>> SAD  1: No convergence for island4493 Box    702.  2270.   828. 2396.
>> SAD  1: No convergence for island1462 Box   1569.  1509.  1684. 1635.
>> SAD  1: No convergence for island3296 Box   1400.  1977.  1473. 2087.
>> SAD  1: No convergence for island6779 Box   1391.  2840.  1419. 2963.
>> SAD  1: No convergence for island8814 Box     73.  3631.   199. 3757.
>> SAD  1: No convergence for island5293 Box   1340.  2452.  1358. 2484.
>> SAD  1: No convergence for island6737 Box   1240.  2829.  1274. 2912.
>> SAD  1: No convergence for island5362 Box   1492.  2481.  1511. 2528.
>> SAD  1: No convergence for island5453 Box   1122.  2507.  1172. 2566.
>> SAD  1: No convergence for island4887 Box   1766.  2344.  1831. 2406.
>> SAD  1: No convergence for island4000 Box    672.  2169.   793. 2213.
>> SAD  1: No convergence for island5307 Box   1281.  2458.  1292. 2487.
>> SAD  1: No convergence for island5608 Box   2173.  2546.  2299. 2671.
>> SAD  1: No convergence for island1851 Box    917.  1582.   979. 1661.
>> SAD  1: No convergence for island4833 Box    605.  2333.   697. 2393.
>> SAD  1: No convergence for island9370 Box   1421.  3662.  1488. 3788.
>> SAD  1: No convergence for island5477 Box   1534.  2514.  1547. 2537.
>> SAD  1: No convergence for island2205 Box   1351.  1648.  1368. 1670.
>> SAD  1: No convergence for island3472 Box   1581.  2040.  1626. 2101.
>> SAD  1: Sucessfully solved12071 islands. 465 OTHERS FAILED TO CONVERGE
>> SAD  1:   2706 islands broken into multiple sources
>> SAD  1:   2706 of these were rejected due to at least partial failure
>> SAD  1:     23 apparently complex islands failed to break into 2
>> SAD  1:  13267 total components had their fits rejected
>> SAD  1:  13267 components rejected for minimum peak
>> SAD  1:    849 components rejected for minimum flux
>> SAD  1:    376 components rejected for maximum size
>> SAD  1:   7091 components rejected for maximum interior X excursion
>> SAD  1:   7168 components rejected for maximum interior Y excursion
>> SAD  1:     11 components rejected for maximum exterior X excursion
>> SAD  1:     26 components rejected for maximum exterior Y excursion
>> SAD  1: Resulting number of sources fit is     0
>>  unknown   SAD  (31DEC13)      2     18-MAR-2014  14:34:05 Page    1
>> ABC         .SUBIM .      1     Disk  1     Plane    1 User       2
>>
>> Window BLC    1    1   1   1  1  1  1 TRC 4096 4096   1   1  1 1 1
>> Sources found down to  0.000015 in JY/BEAM
>> Retry level  0.000015 (JY/BEAM ) plus gain 0.100
>> Using RMS image .
>> Reject components peak <  5.00000 in JY/BEAM
>> Reject components flux < 0.00000
>> Reject components outside window >   0.0 cells
>> Reject components outside image >    0.0 cells
>> Reject residual flux >   1.00000 with gain 0.100
>> Fluxes expressed in units of JY/BEAM
>> NOTE: Fluxes marked by * have been divided by 1000.
>> Errors determined by theory from RMS   5.03 microJy
>> Reference Center: 10 00 28.2001  02 12 36.000
>> All source widths, width errors, and both coordinate errors are in arc s
>> NO corrections for bandwidth smearing have been made
>> Source peaks and fluxes NOT corrected for primary beam
>
> What is CPARM?  This sounds like a case to use CPARM - making large 
> numbers of islands (when you do not need them) and including way down 
> into the noise makes the fitter think that it has failed.  Try first 
> fitting down to 30 sigma or so, then 15 sigma, 5 sigma for 3 rounds of 
> searches.
>
> Eric Greisen