Yes, I corrected the temperatures to +12 K by day and +8 K at night.

And, I acknowledged that this range of temperature is within that shown by natural rock surfaces. OTOH, I showed that the surfaces in question were not illuminated by the sun at the ~14:00 (Mars time) when the daytime IR image was taken, making the nighttime anomaly more significant.

Thanks for your info and assistance in calibrating temperatures. I admit I got the values wrong initially (basically, using data numbers rather than Kelvins in my first analysis). These are the sort of mistakes that happen when using unfamiliar data without clear documentation :-)

Regardless of whether this particular Themis image shows real anomalies, the physical form of water vapor emissions to the surface is likely to be ice towers, rather than hot springs, IMHO.

I am happy to discuss this further with you, online or off-line. I think you have my email address, but if not, you can find it on my website:

http://whitemars.com

Thanks for taking the time to ask cogent questions...