Observation 1

We took two images of the double cluster: NGC869, NGC884, with two different cameras, with different fields of view.

NarrowFieldView_4s_dc869.png widefield_15s_dc869.png

Star Simulation

Main aim this week: background fluctuations

From the larger image, you can see that there is a fluctuation in the background biased towards the left of the image.
Image below is the larger image with a high contrast:


To account for this bias, the image was analysed row by row. Taking a random row of the image and plotting the value with the column number, you get:


The majority of this is background, the spikes are stars. Then, I fit a 2d polynomial to the data. This was repeated for every row, and the parameters for the fit were averaged. This gave me the following function:


This was then used to add background fluctuations to images, poisson fluctuations also implemented.


A row of the above image gives the following


Star Finder

Improved the star finder now out puts the number of stars allong with the coordinates of all the pixels in the stars

Tested on on of Beki's simulated images with no background


It finds that there are 48 stars, there are 47 stars and the image has a white line on the right hand side which is abvoe threashold so it's counting that as the 48th star

I also found the backgroud for one of the real image using the 65X65 box but this took 40 mins to run so I didn't get a chance to plot it.

next step will be to do the aperture photometry and to optimize the background algorithm so it can be useful.

-- BekiChafer - 09 Nov 2017

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng Average_background_of_Image_left_to_right_-_use_for_simulation.png r1 manage 29.1 K 09 Nov 2017 - 22:33 RebekahChafer1  
PNGpng Background_of_Simulated_image.png r1 manage 32.9 K 09 Nov 2017 - 22:42 RebekahChafer1  
PNGpng BgBiasExample.png r1 manage 7016.1 K 09 Nov 2017 - 22:25 RebekahChafer1 High Contrast Image to show bg bias
PNGpng Fitting_Background_to_use_for_simulation.png r1 manage 39.3 K 09 Nov 2017 - 22:30 RebekahChafer1  
PNGpng NarrowFieldView_4s_dc869.png r1 manage 448.6 K 09 Nov 2017 - 14:01 RebekahChafer1 Narrow Field Image
PNGpng Screenshot_2017-11-10_01.15.50.png r1 manage 165.7 K 10 Nov 2017 - 01:18 LunaMarieBorella1  
PNGpng TestbgLarge.png r1 manage 9891.5 K 09 Nov 2017 - 22:36 RebekahChafer1  
PNGpng widefield_15s_dc869.png r1 manage 13704.4 K 09 Nov 2017 - 14:02 RebekahChafer1 Wide Field Image
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Topic revision: r3 - 10 Nov 2017 - LunaMarieBorella1

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