Last night I observed Superbird A, giving me a total of 44 flash period timings this week. I compared the mean flash period between October 1996 and now: Oct 1996 295 periods observed: 11.697 sec mean half-period Nov 1997 44 periods observed: 11.630 sec mean half-period The question is whether or not this difference is significant. I used a statistical method called the "t-test" to compare the two sets of data to determine if there is any detectable difference between the two distributions of timings. The t-test result (3.3) exceeds the t-critical value (1.9), meaning there is a signifcant difference between the two sets of observations. Therefore it appears Superbird has undergone a small spin rate increase over the last 11 months. __________________________________________________ Jim Varney 121.398W 38.458N 8m Sacramento, CA jamesv@softcom.net, sat_watcher@rocketmail.com _____________________________________________________________________ Sent by RocketMail. Get your free e-mail at http://www.rocketmail.com