Difference: 20152710MSciPhotometryLab2 (4 vs. 5)

Revision 527 Oct 2015 - DavidHadden

Line: 1 to 1
 
META TOPICPARENT name="StewartBoogertPhotometry2015"
Initial Investigations
Line: 8 to 8
  In addendum to dark frames taken previously, It was questioned whether or not the 'hot' pixels appearing in longer exposures were a fault of the camera, and appeared in the same places, or whether this was due to other effects. Looking into the dark frames, it was seen that the 'hot' pixels appeared to be randomly distributed over the images for several exposures, appearing both as 'dots' and as 'streaks'. Therefore we conclude that these must be from a foreign influence, not from the CCD or optics of the system. Examples of these can be seen below.
Changed:
<
<
--Pictures (Nice in imshow)--
>
>
120s.png
  Additionally, looking at higher exposure times, there appears to be an increase in the amount of 'dots' and 'streaks', however as of yet this has not yet been thoroughly tested. If this is indeed the case, then this would be consistent with a flux of incident particles decaying at a constant rate, and could be explained by naturally occuring cosmic rays. Upon taking an hour long exposure (significantly longer than previous max of 300 seconds), only very few of these effects were seen, converse to the trend seen for lower exposures. A possible reason could be that over such an exposure, the 'hot' pixels are masked as the backgrond around them is increased, making them less visible, so the chance of seeing any easily detectable events is reduced.
Line: 27 to 27
 
META FILEATTACHMENT attachment="Cosmic_Ray_Investigate.zip" attr="" comment="" date="1445954370" name="Cosmic_Ray_Investigate.zip" path="Cosmic_Ray_Investigate.zip" size="10428637" user="zxap012" version="1"
META FILEATTACHMENT attachment="hour_comparison_correct.png" attr="" comment="" date="1445961890" name="hour_comparison_correct.png" path="Y:\Major Project\Figures\Cosmic_Rays\hour_comparison_correct.png" size="201943" user="zxap012" version="1"
META FILEATTACHMENT attachment="hour_comparison_zoom_correct.png" attr="" comment="" date="1445962277" name="hour_comparison_zoom_correct.png" path="Y:\Major Project\Figures\Cosmic_Rays\hour_comparison_zoom_correct.png" size="247138" user="zxap012" version="1"
Added:
>
>
META FILEATTACHMENT attachment="120s.png" attr="" comment="" date="1445964185" name="120s.png" path="Y:\Major Project\Figures\streaksanddots\120s.png" size="463785" user="zxap012" version="1"
 
This site is powered by the TWiki collaboration platformCopyright © 2008-2018 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding RHUL Physics Department TWiki? Send feedback