What is "co-adding" ?

[rogerg]

G'day all,

Does anyone know what it is to "co-add" astronomy images? It's a type of stacking but it's not clear to me if it's the same as to simply do an "add" or "sum" frames.

Thanks,
Roger.

[Peter Ward]

Roger,

Co-adding images is a technique many digital camera users to achieve two ends:
1) lower the noise in an image
2) improve the signal/dynamic range

You can combine images using many methods. Sum, average, median etc.

Many software packages will let you do this, as well as give you various ways of aligning the images....for example, you could align on the head of a comet, rather than the background stars.

Hope that helps

Peter

[rogerg]

Interesting, so by what you're saying, "co-adding" = "stacking" = "combining". Easy.

I figured it must have been a particular type of stacking/combining frames.

Thanks