Sunday night I decided to haul my two year old 8" f/5.3 dob out and check out Mars. I have been getting some awfully nice views of Mars through it during this opposition. Sunday was no exception. I was trying out my new Orion ``Shorty Barlow''. When combined with my 6mm Vixen eyepiece, the magnification was ~380 power. Pretty nice, although the damping time on my telescope could be better. The nudge-drift cycle is fine at 100-150x, but 380 is a bit tough. Still the polar ice cap was beautiful and obvious once the mirror and tube cooled down. Detail became more apparent, and I made a couple of quick sketches. When I returned to my house, I consulted xephem and found that indeed, such features might exist :) I identified the dark patch near the pole as the Niliacus Lacus. Also visible were the Meridiani Sinus, the Margaritifer Sinus, the Aurora Sinus, Nectar and Solis Lacus. Pretty nice! :)
I also took the time to actually star test my telescope against Polaris. The presence of nice concentric diffraction rings inside and outside of focus testified that my collimation was indeed pretty good. I did notice that inside focus, the outer ring appears to be a bit jaggy and a bit brighter than the other rings. *sigh* Another turned edge. I always tell students to black out the edge because edges are almost always never correct, but I must admit I never do it myself. Still, I will have to do that the next time my telescope is out of the tube. I also want to replace my tall focuser with something a little lower. But performance tuning scopes is part of the fun of building them!
For those of you who have been ignoring Mars, it's small, but high up! Give it a check. Mark VandeWettering