Jenn's Astronomy Project- Object Intro (16.280)

Jenn's 16.280 Project Assessment of the Basic Image ^*
* dark subtracted, flat fielded, scaled but not combined(Values in italics are values for image before scaling. They are different because when we scaled the image we conserved the flux and so we had the same number of counts in a smaller space)

Clear
Blue
Red

Click on any image to see a larger version.

Assessment of the image taken through the Clear filter:

Surface plot (seen from the North-East)

Pixel Counts &
Explanation of Image Image

Background=1155
Standard Deviation=16.28
Background=986.4
Standard Deviation=13.78
This is a radial plot across the whole image from the center out. I chose this image because it takes into account every value, shows how the background tends towards a mean value, shows the associated standard deviation (thickness of the 'background' line) and also shows the stray pixels.

Faintest Stellar Object=1197.19
Faintest Stellar Object=1020
I chose a line plot over a radial plot because for the fainter images it often wouldn't give a radial plot. (I believe the error was associated with the fact that it wouldn't be able to calculate statistics about the radial plot such as FWHM and got 'confused'.)
I chose a plot averaged over two lines to beat down the noise a little bit. The faint regions were always more than two lines thick and often the center could very well be taken to be between two lines and so felt this was justified.

Faintest region=1178.43 (plot not shown)

Brightest Stellar Object=7625.25
Brightest Region/Stellar Object=6551

Brightest Region of Objects=1834.62

The Average FWHM (Full Width Half Maximum) of the Stars:
From Line Gaussian=4.037
From Column Gaussian=4.5412
This shows there was a bit of trailing in the horizontal or East-West direction (which was the direction of tracking CCDOPS controlled)
Resolution:
To be resolved two stars need to be separated by at least their FWHM. The most precice FWHM is the FWHM calcualted from a radial plot as it takes points all the way around the star and not just along one line or column which in this case is 3.8 pixels which translates into 3.42 arcseconds. (the chip has a Field of View of 3'.6 by 4'.7 and is 242 by 322 pixels after scaling. Consiquently each pixel is 0.9 arcseconds square)

Assessment of the image taken through the Blue filter:

Surface plot (seen from the North-East)

Pixel Counts &
Explanation of Image Image

Background=53.19
Standard Deviation=5.562
Background=46.16
Standard Deviation=7.782
This plot was chosen for the same reasons as for the clear image. In this one it is particularly interesting as it shows lots of stray pixels. There is one whose value is -2898!

Faintest Stellar Object=63.46
Plot details chosen for the same reasons as for the clear filter data.

Faintest Region=69.24 (plot not shown)

Brightest Stellar Object=235.907
Brightest Stellar Object=197.579

Brightest Region of Objects=90.06 (plot not shown)

The Average FWHM (Full Width Half Maximum) of the Stars:
From Line Gaussian=4.756
From Column Gaussian=4.783
This shows there was a touch of trailing in the horizontal or East-West direction which was the direction of tracking CCDOPS controlled but it is only .03 pixels and so the tracking here was very consistant.
Resolution:
To be resolved two stars need to be separated by at least their FWHM which, found from a radial plot is 4.62 pixels which translates into 4.16 arcseconds.

Assessment of the image taken through the Red filter:

Surface plot (seen from the North-East)

Pixel Counts &
Explanation of Image Image

Background=1294
Standard Deviation=18.16
Background=1105
Standard Deviation=19.86

Faintest Stellar Object=1348.23
Faintest Stellar Object=1165.94

Faintest Region=1324.62 (plot not shown)

Brightest Stellar Object=3883.35
Brightest Stellar Object=3464.18

Brightes Region of Objects=1716.95

The Average FWHM of the Stars:
From Line Gaussian=4.588
From Column Gaussian=4.322
This shows there was a bit of trailing in the vertical or North-South direction which was the direction we controlled. The trailing is about .3 pixels and so is fairly negligable over all.
Resolution:
To be resolved two stars need to be separated by at least their FWHM which, found radially is 4.43 pixels which translates into 3.99 arcseconds.

Other:
This is a linear plot from one end of the chip to the other averaged over the width of the chip and shows a gradient in the background.
My first tendancy was to say that the responce of the chip to red light changed from one side of the ccd to the other. The error in that statement is that having taken flat field images through the red filter this variation in the responce should have been accounted for.
The only other explanation might be that the actual amount of light falling on the chip changed across the field of view. According to Chris Brown (who taught us to use the camera among other things) It may be that the tracking camera was blocking some of the light near the edge.

Back

Pixel Counts & Explanation of Image	Image
Background=1155 Standard Deviation=16.28 Background=986.4 Standard Deviation=13.78 This is a radial plot across the whole image from the center out. I chose this image because it takes into account every value, shows how the background tends towards a mean value, shows the associated standard deviation (thickness of the 'background' line) and also shows the stray pixels.
Faintest Stellar Object=1197.19 Faintest Stellar Object=1020 I chose a line plot over a radial plot because for the fainter images it often wouldn't give a radial plot. (I believe the error was associated with the fact that it wouldn't be able to calculate statistics about the radial plot such as FWHM and got 'confused'.) I chose a plot averaged over two lines to beat down the noise a little bit. The faint regions were always more than two lines thick and often the center could very well be taken to be between two lines and so felt this was justified. Faintest region=1178.43 (plot not shown)
Brightest Stellar Object=7625.25 Brightest Region/Stellar Object=6551 Brightest Region of Objects=1834.62
The Average FWHM (Full Width Half Maximum) of the Stars: From Line Gaussian=4.037 From Column Gaussian=4.5412 This shows there was a bit of trailing in the horizontal or East-West direction (which was the direction of tracking CCDOPS controlled) Resolution: To be resolved two stars need to be separated by at least their FWHM. The most precice FWHM is the FWHM calcualted from a radial plot as it takes points all the way around the star and not just along one line or column which in this case is 3.8 pixels which translates into 3.42 arcseconds. (the chip has a Field of View of 3'.6 by 4'.7 and is 242 by 322 pixels after scaling. Consiquently each pixel is 0.9 arcseconds square)

Pixel Counts & Explanation of Image	Image
Background=53.19 Standard Deviation=5.562 Background=46.16 Standard Deviation=7.782 This plot was chosen for the same reasons as for the clear image. In this one it is particularly interesting as it shows lots of stray pixels. There is one whose value is -2898!
Faintest Stellar Object=63.46 Plot details chosen for the same reasons as for the clear filter data. Faintest Region=69.24 (plot not shown)
Brightest Stellar Object=235.907 Brightest Stellar Object=197.579 Brightest Region of Objects=90.06 (plot not shown)
The Average FWHM (Full Width Half Maximum) of the Stars: From Line Gaussian=4.756 From Column Gaussian=4.783 This shows there was a touch of trailing in the horizontal or East-West direction which was the direction of tracking CCDOPS controlled but it is only .03 pixels and so the tracking here was very consistant. Resolution: To be resolved two stars need to be separated by at least their FWHM which, found from a radial plot is 4.62 pixels which translates into 4.16 arcseconds.

Pixel Counts & Explanation of Image	Image
Background=1294 Standard Deviation=18.16 Background=1105 Standard Deviation=19.86
Faintest Stellar Object=1348.23 Faintest Stellar Object=1165.94 Faintest Region=1324.62 (plot not shown)
Brightest Stellar Object=3883.35 Brightest Stellar Object=3464.18 Brightes Region of Objects=1716.95
The Average FWHM of the Stars: From Line Gaussian=4.588 From Column Gaussian=4.322 This shows there was a bit of trailing in the vertical or North-South direction which was the direction we controlled. The trailing is about .3 pixels and so is fairly negligable over all. Resolution: To be resolved two stars need to be separated by at least their FWHM which, found radially is 4.43 pixels which translates into 3.99 arcseconds.
Other: This is a linear plot from one end of the chip to the other averaged over the width of the chip and shows a gradient in the background. My first tendancy was to say that the responce of the chip to red light changed from one side of the ccd to the other. The error in that statement is that having taken flat field images through the red filter this variation in the responce should have been accounted for. The only other explanation might be that the actual amount of light falling on the chip changed across the field of view. According to Chris Brown (who taught us to use the camera among other things) It may be that the tracking camera was blocking some of the light near the edge.