Will the real rim please stand up

[imported_Thumper]

When there is an image that contains a nice sharp impact crater of x diameter it would seem easy to mark the 'rim' at the well defined raised feature directly surrounding the bowl. But there are times where if you look closely you can see a faint ring located some 3 to 8 x distance out from the defined crater. Usually the surface texture is very slightly smoother or just different in appearance within this faint larger ringed area. I have already looked through the tutorial, FAQs, and glossary images, but unless I just plain missed it I have not found a definitive answer for which we should be marking as the actual 'rim' feature. Especially where the sharp inner crater is below the minimum marking size but the surrounding outer ring is well over the cutoff diameter.
Should I just mark both features as concentric craters?

Next. If I 'loose' an image for some reason before I click the Done Working button, is anything saved at your end or is it plain gone?

[IreneAnt]

Hi Thumper,

I would really need to see an image to understand what you are referring to. If you can post one as soon as you find one, that would be very helpful.

In the mean time, my advice would be to mark the most obvious rim. Believe it or not, this is also an issue when dealing with multi-ring impact basins, and scientists have still not come to a consensus on which rim marks the "edge" of the crater.

As to the saving question, I will let one of our developers address that one.

Happy marking

[lynx1]

Would this be an example of a double-impact crater? It seems like there are two central peaks and the rim seems to be oblong in shape.

http://s3.amazonaws.com/cosmoquest/d...RE/0/00176.png

[IreneAnt]

Hi mangrovetom,

Here's the image you linked to:


If you are referring to the big crater at centre right, then I would say it's not a double crater. I think what is happening here is that part of the upper left wall slumped creating a shelf-like feature half way down the crater wall. The crater itself is a little odd shaped, but I think that is related to the rim being affected by an old degraded crater at the 5 o'clock position.