-- LauraBevilacqua - 18 Oct 2016

To do by Friday:

• Select star cluster for observations
Anisha:
• Fix histrogram from last week
• Plot median as a function of exposure time
• Plot error as function of exposure time
Aaron:
• Figure out how to save simulated images as FITS files.
• Give Laura test fits file, with recorded star positions and intensities/counts.
Laura:
• Convert Aaron's fits file to image
• Test whether program counts accurately
Weekly Progress:

Anisha:

• Corrected histrogram of number of photoelectrons for a 0.1s exposure in the dark frame with 500 bins - logarithmicly normalized:

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

• Line of best fit: y = 917.43 + 0.08x

• Error as a function of exposure time:

• Line of best fit: y = 15.76 + 0.73x

Aaron:

• Implemented a true 2D Gaussian with correlation between x and y (with correlation coefficient P (rho)):
• (Note: normalisation factor is ignored so far for programming purposes; maximum pixel value is being used in its place)
• Integration of 2D Gaussian in this form is done numerically.
• Tested for P =0, P =0.5, P =0.999 (sigma_x=sigma_y=3 in each case)
• (Note - image is rotated 90 degrees clockwise)
• Also - found a way to save images as FITS files, similar to images gained from observations.
• Simulated test images for Laura - all on 100x100 pixel grids, using calculated mean pixel values instead of randomised poisson values:
• 1 star at (50,50), peak=60000.
• 3 stars with decreasing intensities: (25.25), peak=10000; (50,50), peak=1000; (25,25), peak=100
• 8 stars with peak=60000, in pairs which are closely spaced: (45,20), (55,20); (44,40), (56,40); (43,60), (57,60); (42,80), (58,80)
• 8 stars with peak=60000, peaks are out of frame: (100,20), (102,40), (104,60), (106,80), (-8,20), (-10,40), (-12,60), (-14,80)
Laura:
• Fits files from Aaron successfully converted to monochrome images
• Images scanned for stars and correct star count is returned
• Edge detection helps identify star position

• The maximum pixel value was found to be 65195 from the fits file below, as opposed to Aaron's given value of 65535
• Threshold of 100 set so if pixels are above this value they are set as white background, if below they are coloured black (remember reverse grayscale):
• Edge detection:

• Maximum pixel value found to be 62673, compared to Aaron's 60000:
• Threshold set as 20 so that stars don't touch, achieves accurate count of 8:

Topic attachments
I Attachment History Action Size Date Who Comment
png Error_as_a_function_of_exposure_time_with_best_fit.png r1 manage 31.3 K 20 Oct 2016 - 18:01 AnishaVadher Error as a function of exposure time
jpg FinderTest1a.jpg r1 manage 6.5 K 20 Oct 2016 - 18:07 AnishaVadher
png FinderTest1a.png r1 manage 14.5 K 21 Oct 2016 - 12:16 AaronAndrews Finder test 1: 1 star
png FinderTest1a_count.png r1 manage 12.8 K 20 Oct 2016 - 18:07 AnishaVadher
jpg FinderTest1a_mon.jpg r1 manage 5.4 K 20 Oct 2016 - 18:07 AnishaVadher
png FinderTest2.png r1 manage 16.5 K 21 Oct 2016 - 12:17 AaronAndrews Finder test 2: 3 stars, decreasing intensities
jpg FinderTest3.jpg r1 manage 14.1 K 20 Oct 2016 - 18:07 AnishaVadher
png FinderTest3.png r1 manage 35.9 K 21 Oct 2016 - 12:17 AaronAndrews Finder test 3: 8 stars, closely spaced
png FinderTest3_count.png r1 manage 15.5 K 20 Oct 2016 - 18:07 AnishaVadher
jpg FinderTest3_mon.jpg r1 manage 6.2 K 20 Oct 2016 - 18:07 AnishaVadher
png FinderTest4.png r1 manage 17.0 K 21 Oct 2016 - 12:18 AaronAndrews Finder test 4: 8 stars, out of frame
png Histogram_of_number_of_pixel_values_for_0.1s_exposure_500_bins.png r1 manage 18.4 K 20 Oct 2016 - 17:53 AnishaVadher Corrected histrogram of number of photoelectrons for a 0.1s exposure in the dark frame with 500 bins - logarithmicly normalized
png SkewTest2.png r1 manage 18.6 K 18 Oct 2016 - 22:46 AaronAndrews Testing x and y correlation (P) for P=0, P=0.5, P=0.999
png The_median_intensity_as_a_function_of_exposure_time_with_best_fit.png r1 manage 36.2 K 20 Oct 2016 - 17:55 AnishaVadher The median intensity as a function of exposure time.
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Topic revision: r11 - 21 Oct 2016 - AaronAndrews

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