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Changes between Version 10 and Version 11 of PS1_GPC1_Magic_Status_20090628


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Timestamp:
Jun 28, 2009, 10:15:07 PM (17 years ago)
Author:
eugene
Comment:

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  • PS1_GPC1_Magic_Status_20090628

    v10 v11  
    3939We have also had concerns that some of the Magic false positives are caused by fractional errors in the variance.  We have found that the GPC1 data processed to the difference level has a higher pixel-to-pixel standard deviation in the background than expected from the noise propagation.  In the case of the exposure above, the effect ranges from about 15% to 25% (ie, stdev is 15% to 25% higher than expected).  We have shown that this effect does not appear in our simulated data analysis, which seems to suggest it is not caused by the software specifically.  The last four images illustrate the impact of an error in the variance level of this scale. 
    4040
    41 || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.raw.clusters.png,550)]]
    42 || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.raw.streaks.png,550)]]
    43 ||
    44 
    45 || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.sig29.clusters.png,550)]]
    46 || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.sig29.streaks.png,550)]]
    47 ||
     41|| [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.raw.clusters.png,550)]] || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.raw.streaks.png,550)]] ||
     42|| [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.sig29.clusters.png,550)]] || [[Image(http://kiawe.ifa.hawaii.edu/eugene/software/magic/72897.sig29.streaks.png,550)]]  ||
    4843
    4944The top pair of images illustrate the magic analysis using the standard threshold of 2.3 sigma.  The bottom pair illustrate the effect of changing the threshold to 2.75 (roughly 1.2 times the standard value, thus canceling the error in the variance).  The left set of images shows the pixel cluster that were detected in significant peaks in the hough transform; the right set show the streaks which resulted from those detected clusters.