Ok, looking at the JPL site I mentioned in my last message it looks like closest approach for SPOC will occur at 0800 UT (0200 MDT) on the 27th when an observer will be 55,754,437.643 km away from Mars. Of course it that observer stands up on the roof of SPOC that will decrease to 55,754,437.640 km :-) I'm not sure if that is from the observer to the surface of Mars or to its center. And I'm still not sure about the light travel thing. That is are we closest at 0200 or is that when the light arrives from when we were closest, or do we have to wait until the light gets here. So, depending on interpretation and with one way light time being 3.099613 minutes, that time could be 0200 plus or minus 3 minutes and 5.97678 seconds. Ok, is everyone as confused as I am? :-) Hope to see y'all at SPOC tonight! Patrick -- Patrick Wiggins NASA Solar System Ambassador to Utah http://planet.state.ut.us 435.882.1209 (6 a.m. to 3 p.m.) 801.918.9092 (3 p.m. to 6 a.m.)