--
AnishaVadher - 16 Jan 2017
Prior to determining flux:
- Ran mode and Sigma filters on simulated blue and visual Double Cluster, with flat background (mean=900, sigma=10)
- Ran star finder, used threshold = pixel Mode + 1*maximum sigma.
- For each cluster of pixels found by algorithm, found approximate centre coordinates of star using:
('x' = x or y coordinates)
Aperture Photometry:
- Subract mode filter from image to remove background.
- Set radius around central coordinates of star.
- Sum ADU of each pixel within set radius, gain 'raw flux' value (not true total flux).
Setting radius of aperture
- Flux of the brightest star in double cluster as a function of radius:
- Radius will be set to 12 from the graph as the flux levels out above 12.
Matching Stars in Different Frames
- For simulations, frames are aligned
- For both simulated frames, minimum seperation between stars (in pixels) ~3.
- Match stars with minimum seperation.
- For real data, calculate transformation based on position of brightest star.
Calculate Magnitude
- Used following equation to calculate magnitudes of simulated data (simplified from proper magnitude calculation):
- c is a scaling factor - calculated based on difference of original and calculated magnitude of brightest star.
- HR diagram (with c=0):
-
- Total stars matched and plotted: 86
- Comparing with input magnitude - set scale factors in reconstructed data to match minimum magnitude point in true data:
-
- Also attempted for real data - not properly scaled, and needed to set threshold to mode+5*sigma:
-
- Total stars matched and plotted: 96