Here is a quick process of the last image from the session last night, showing Mars with the terminator projection. That’s the term that Richard McKim, Director of the BAA Mars Section, used in his report today. So, I think that’s the most appropriate term to describe this phenomena until we learn more about its nature.
The seeing was very good at times last night, but I chose to process the last image of the session first because that’s when I was most likely to capture the CM (central meridian — the coordinate system we use to identify what part of mars is facing us) where the projection is located. The projection is indeed still present and looks quite like a “nipple” in this image.
I will update this with additional images from the session (including one that I think was taken in near-perfect seeing) this evening. Given that we have one more night of possible imaging in the forecast, my plan is to take data first and process later. So, I may not get to do a complete update on this phenomena until the clouds and rain arrive.
Note the inset shows the terminator projection enlarged 200%, relative to the original image, and slightly enhanced.
Here’s one from earlier. The terminator projection is barely perceptible coming over the limb.
And finally one from the beginning of the session showing extensive cloudiness across the globe, but taken in excellent seeing.