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Re: [APML] Redo- Sagittarius - M8 to M17
>I have no idea what a gaussian like function would look like, but how
>do you go about doing this?
Have you ever seen a gaussian bell, the statistical (normal) distribution?
If not, just think on a shape like this /\, and inverted "V". Now smooth it so it looks more like an inverted "U", but the outer regions fall "slowly".
Here is a graph of the function:
(first page in a Google search)
Look down for a 3D plot too.
Now, instead of a third coordinate (z), use pixel values. Brighter values are similar to higher z values. So, keeping a gaussian like profile of our stars is a short way to say that we'll keep the center bright, and slowly let the values go down to the background, instead of an uniform disc.
Of course that our profiles aren't gaussian curves. We keep that name for the "ideal" profile of a star. Becouse they are pinpoint sources (they are very, very far away), the atmosphere works like a diffusion filter, transforming that pinpoint source into a gaussian like distribution of light around the original source. This is also called "seeing". Seeing is generally calculated as the full with at half maximum (fwhm) of a gaussian curve, fited to the data. The standard deviation is used too. BTW, every star, no matter the brightness, or "size", have the same FWHM (pretty close).
The bottom line is that keeping a gaussian like profile is much more close to the true aspect of a star, "inside" Earth, than a flat disc. Also I found it more pleasant!
Regards,
Carlos Milovic F.
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