I began this sketch before sunset and the seeing was average but the advantage gained by using a single polarizing was dramatic.
The North Polar Cap was clearly seen and it shrinkage has slowed. Utopia was seen south of the pole and Syrtis major was on the sunrise limb. Between Syrtis major and minor, Hesperia was visible in the direction of the South Polar region. Mare Cimmerium appeared as a dark line projecting toward the central meridian. The region of Elysium appeared darker than the surroundings and the region of Amazonis looked to be under clouds or haze or both near the preceding limb.
For a time I was able to add a barlow to the eyepiece and see Mars fairly well at about 600x.
The eyepiece sketch is the one on top in graphite pencil. The second color sketch was made indoors.
White sketching paper 8" x 11"; HB graphite pencil, blending stumps for blending orange, brown and red Crayola pencil shavings.
Date 3/26/2010 – Time 23:30-0:10 UT
Telescope: 10 inch f/5.7 Dobsonian and 4mm eyepiece 362 x, polarizing filter
Temperature: 2°C (35°F)
partly cloudy, calm, dry air conditions
Seeing: Average-Above average 3/5