Mars – February 18, 2010

Mars – February 18, 2010
Sketch and Details by Frank McCabe

Conditions were much improved over those of last Thursday for observing and sketching the planet Mars. The air column above me was mostly steady with temperatures just a degree above freezing.
Mars is now growing smaller in the eyepiece at 13.0″ of arc and 0.72 A.U. from us. 98% of the disk is illuminated and shining at visual magnitude -0.9. The central meridian of Mars was centered around 269° at the time of the sketch.
The north polar cap is clearly diminishing in size and visual brightness. In addition to the major features such as: Syrtis Major, Hellas, Mare Australe, Utopia/Casius, Mare Cimmerium and Mare Tyrrhenum; I was able to see clouds over the Elysium volcanic field and the albedo feature Nodus Alcyonis also appeared during moments of very steady seeing.
Before beginning this sketch I spent 30 minutes looking at Mars through red, green and light blue filters to assist with locating low contrast features.

Sketching:
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 yellow Crayola pencil shavings.
Date 2/19/2010 – Time 3:00-3:35 UT
Telescope: 13.1 inch f/5.9 Dobsonian and 9mm eyepiece 218x
Temperature: 1°C (34°F)
clear, calm
Transparency 4/5
Seeing: Antoniadi III

Frank McCabe