Difference: StewartBoogertPhotometry20161007 (1 vs. 4)

Meeting 20161007

• Data taking 20161004 : Exposure time scan at 5 degrees

• 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.

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)

• 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

Anisha

Aaron - Star Field Simulation

'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)
• 

• 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)
• 
• Example 2: (1530x1020 pixels, 0-65535 grey value range, 50 stars) (Same size of images taken by telescope system)
• 
• Running Python Programs/Functions:

1. 1. Change working directory
   2. 'import [filename]' (without '.py')
   3. '[filename][functionname](variables)'

• If file is already imported, replace 'import' with 'reload' to load any changes.
• To show an image produced by a function:

1. 1. 'a=[filename][functionname](variables)'
   2. 'imshow(a, cmap='Grey_r)' (use 'imshow(a)' for colourmap image instead of greyscale image)

---+++ Laura

• Anisha
• Aaron
• Laura