-- AnishaVadher - 14 Oct 2016


  • Working out how much background for each pixel
  • Plotted a histogram of number of photoelectrons against the frequency for a 0.1s exposure in the dark frame which follows a Gaussian distribution
  • Histogram_of_number_of_photoelectrons_for_0.1s_exposure.png
  • Number of photoelectrons = pixel value (ADU) * Gain
  • Gain = 2.3 e/ADU (value from PH2900 report)
  • From the histogram I will obtain the value at the peak and the error from the FWHM
  • Error in the peak = FWHM/2.35
  • I will get these statistics for each exposure time in the dark frames that I have taken and plot the peak value as a function of exposure time and the error as a function of exposure time.
  • There are big gaps between the bins which I am not sure why.
  • Edit - the gaps are due to the fact that the histogram only takes integer values so increasing the number of bins leads to more gaps in the histogram.
  • Histrogram of number of photoelectrons for a 0.1s exposure in the dark frame with 45 bins.:

  • Also plotted a histogram for the sum of pixel along the x-axis values against frequency for a 0.1s exposure in the dark frame which follows a Poisson distribution
  • The histograms from the sum of pixels along the y-axis follows a Gaussian distribution.

  • Plotted the median intensity of the pixels as a function of exposure time using the values given from the image using np.median in python. I am yet to work out the errors.

  • The median intensity as a function of exposure time.:

  • Star field simulation notes - part two discussed. Note: from now on, weekly work will be presented in these 'meeting' pages.
  • Discussion of work so far (i.e what needs to be changed/reviewed):
    • Alternative to using numerical integration - use cumulative distribution function, find values for both limits, then use difference. Will most likely be faster method.
    • 2D gaussian function not completely correct - x and y components are correlated.
  • What to work on next:
    • Output simulated star field data to FITS file - same file format as what is produced by camera.
    • Simulate a background based on Anisha's analysis - scale to signal correctly, take exposure time into account.
    • Create example starfield for Laura, with set positions etc., in order to test star finding program. *

This topic: Public > StewartBoogertPhotometry20161014
Topic revision: r2 - 14 Oct 2016 - AaronAndrews
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