Improvements

• Following on from last weeks meeting, it was suggested the colourmaps used were not overly clear.
• A version with better contrast has been chosen, and an example is seen below, with the old version, for comparison purposes.

• Next the issue of over anti-aliased pixels in imshow was addressed.
• Using the interpolation = 'nearest' option, future imshow images should display proper pixels, as seen below.

Accounting for Dark Frames

• In order to accurately analyse the stars, the background caused by the camera needs to be removed.
• To do this, a dark frame was scaled down and taken away from the image seen above.
• An improved image can be seen below, with much of the noisy background regions reduced considerably.

New algorithm for finding stars

• Used algorithm as showed here.
• We impleted some arbitrary threshold.
• We set signal to 1 and background to 0.
• We impleted the algorithm and unfortunately it has a similar problem to the previous algorithm.

• It thinks that points not touching diagonally are stars.
• At the threshold of 1000 photoelectrons we have the following:

• We implented a crude to find the centers of each star. We only need it as an initial parameter that we will feed to our Gaussian to estimate a much better center position.
• We found the centers in the following way:

1. We had the x and y coordinates of all the pixels of each star.
2. We summed all x and all y for each star and then divided the sums by the amount of x and y coordinates we had.
3. This we used as our centers.

Better background determination

• Split each image into 4 quadrants such that:

• Found the following modes:

Filter	Exposure Time (s)	Mode in Quadrant 1 (photoelectrons )	Mode in Quadrant 2 (photoelectrons )	Mode in Quadrant 3 (photoelectrons )	Mode in Quadrant 4 (photoelectrons )
Focus	10	47.32	46.84	47.80	46.84
Focus	10	47.08	46.37	47.56	46.61
Focus	10	46.61	45.65	46.84	45.89
Focus	10	47.56	47.08	48.28	47.08
Focus	10	47.80	47.32	48.52	47.56
Focus	10	47.56	46.84	48.04	47.08
Focus	10	48.52	47.56	49.00	48.04
Focus	10	47.56	46.61	47.80	46.61
Focus	10	47.80	46.84	48.28	47.08
Focus	10	48.04	47.32	48.76	47.56
Blue	90	5.31	5.20	5.36	5.26
Blue	90	5.39	5.28	5.44	5.31
Blue	90	5.34	5.20	5.36	5.26
Green	40	12.85	12.61	12.97	12.68
Green	40	12.97	12.67	13.03	12.73
Green	40	12.61	12.31	12.67	12.43
Red	40	14.10	13.86	14.16	13.86
Red	40	14.04	13.80	14.04	13.86
Red	40	13.92	13.68	13.98	13.80

Location 2:

Filter	Exposure Time (s)	Mode in Quadrant 1 (photoelectrons )	Mode in Quadrant 2 (photoelectrons )	Mode in Quadrant 3 (photoelectrons )	Mode in Quadrant 4 (photoelectrons )
Focus	60	24.54	24.06	24.74	24.18
Focus	60	23.46	22.86	23.58	23.10
Focus	60	22.98	22.47	23.14	22.78
Green	120	7.19	7.03	7.27	7.11
Green	120	7.13	6.91	7.15	6.99
Green	120	7.03	6.83	7.09	6.93
Red	120	8.40	8.25	8.46	8.31
Red	120	8.37	8.21	8.38	8.25
Red	120	7.97	7.75	8.01	7.85

-- DavidHadden - 24 Nov 2015