I'm looking for some guidelines to help better interpret the information CCD inspector provides.

I reviewed the help section which illustrates everything except an understanding of what the data equates too.

Example:
Collimation what number would be considered appropriate a high number of 17 or low number of 2?

Curvature is obvious

Tilt in x and y access I'm assuming if the number is the same for both axis this is a good thing ;so whats the tolerance too look for which indicates a not so good reading.

Thanks
Troy

Hi Troy,

For collimation purposes, you have two possible ways to proceed in CCDInspector v2:

1. Use the multi-star collimator (in focus, requires lots of stars in FOV and reasonably well-sampled image), or

2. Use the single defocused star collimation method. Requires a single bright star and will work with any image scale.

When using the multi-star collimation method, the collimation error values break down as follows:

- If greather than 10 arcseconds, collimation can and should be adjusted
- If between 5 and 10 arcseconds, collimation is pretty good, but can be improved
- If less than 5 arcseconds, don't bother trying to improve it unless the seeing conditions are really good.

When using a single defocused star collimator, I've been able to get the error down to a value of around 1. How close you can get to this will depend on the seeing conditions. Once the error is reduced to the point where the error direction keeps changing in randomly, you've reached the limit of what can be done under current seeing conditions.

Tilt in X and Y is the amount of defocus (FWHM arceconds difference) between left and right and top and bottom of the image. In CCDI v2, I introduced a value called Total Tilt, which shows the direction and percent FWHM difference of the line of maximum change across the image.

What is tolerable for tilt values depends on your image scale and system resolution. I find that tilt of under 5-8% is not obvious. Tilt of 10% or more become more pronounced. What is probably more obvious with tilt are the other distortions caused by it, such as star elongation/coma.

Hope this helps.

Regards,

-Paul

Hi Paul

Regarding the collimation value I was referring to the results which are displayed when viewing the curvature within CCD Inspector.

Example I'm viewing a 60 sec frame using CCD Inspectorand the collimation reads 6.4"

Thanks for the explantion for the other inquiries.
Troy

Hi Troy,

The collimation value displayed on the curvature map is the same one computed by the multi-star collimator in CCDInspector. The description I gave applies to both values:

quote:

- If greather than 10 arcseconds, collimation can and should be adjusted
- If between 5 and 10 arcseconds, collimation is pretty good, but can be improved
- If less than 5 arcseconds, don't bother trying to improve it unless the seeing conditions are really good.

Regards,

-Paul