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META TOPICPARENT |
name="StewartBoogertPhotometry2016" |
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< < | Data taking 20161004 : Exposure time scan at 5 degrees |
> > | Meeting 20161007 |
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< < | Anisha |
> > | People present: Stewart Boogert, Glen Cowan, Aaron Andrews, Anisha Vadher, James Angthopo, Will Burrows |
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< < |
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> > | Anisha: |
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< < | Aaron - Star Field Simulation |
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< < | 'Basic' simulation program (04/10/2016): Simulation_test1.py.txt
- Simulation generates stars with random positions.
- Canvas size and no. of stars are variable.
- No gaussian profile for stars or grey values (pixel value is either 0 or 1).
- Example output: (100x100 pixel canvas, 50 stars)
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Improvement - Gaussian star profiles (05/10/2016): Simulation_test2.py.txt
- Generated stars now have 2d gaussian profiles.
- Maximum grey values (gaussian peak values) are randomized - can result in star not appearing in output.
- Example output: (100x100 pixel canvas, 0-100 grey value range, 10 stars)
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- Example 2: (1530x1020 pixels, 0-65535 grey value range, 50 stars) (Same size of images taken by telescope system)
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- Running Python Programs/Functions:
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- Change working directory
- 'import [filename]' (without '.py')
- '[filename][functionname](variables)'
- If file is already imported, replace 'import' with 'reload' to load any changes.
- To show an image produced by a function:
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- 'a=[filename][functionname](variables)'
- 'imshow(a, cmap='Grey_r)' (use 'imshow(a)' for colourmap image instead of greyscale image)
- Next Tasks:
- Integration over each pixel, instead of taking central value.
- Assume each pixel is a poisson variable - for any calculated pixel value, get random poisson distributed value (e.g. calculated pixel value is 17.5, use as mean for poisson distribution).
Laura |
> > | Aaron: |
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- Current task: Star field simulation.
- End goal of task is to generate image that is similar to what would be seen via the telescope.
- Currently have program capable of generating an image as an array of pixels and filling flux values calculated in relation to stars:
- Image size (no. of pixels in X and Y axis) and number of stars generated are variable.
- Stars generated with 2d gaussian profile - each pixel filled with sum of intensity contribution from each star.
- X and Y coordinates and peak value for each star is randomised, sigma values (in gaussian) set to 3 pixels for all stars - Eventually these will all come from simulation input data.
- Suggestions:
- Currently pixel value is calculated in relation to central position of each pixel - should be integral over pixel area.
- Pixel values represent photon counts, hence follow Poisson distribution. Therefore, generate pixel value by using integrated value as mean.
(Laura - not present)
Joint task:
- Decide on obsevation target:
- Stellar cluster.
- Needs to be visible at night for next few months.
- Also needs to be visible at reasonable time of evening/night (e.g. max. altitude between 7pm and 10pm)
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-- StewartBoogert - 07 Oct 2016 |