# Difference: StewartBoogertPhotometry20161014 (1 vs. 2)

#### Revision 214 Oct 2016 - AaronAndrews

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 META TOPICPARENT name="StewartBoogertPhotometry20161014"
-- AnishaVadher - 14 Oct 2016
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Anisha:

• 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
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• 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.:
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Aaron:

• 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. *
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#### Revision 114 Oct 2016 - AnishaVadher

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 META TOPICPARENT name="StewartBoogertPhotometry20161014"
-- 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
• 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.:

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