The trading for 2009.01.23 was amazingly textbook from a Gann level progression. Measured from the low of the morning (small red dash), we went up to the 180° level. After hitting the 180, we typically look for a retracement to 90° or 45° before moving back above 180°. In this case, we went to 90°, then eventually stopped dead at the 360° level (835.75). At this point, I looked for a reversal... see 2nd screen shot below. (FYI, 824 is from a daily Gann level)
Since we completed the 360° cycle, I changed my measurement from the bottom-up, to the top-down (see small blue dash on the top pivot). (You now see the levels increasing from the top down.) As you can see the trend channels held very nicely as well. (824 is from a daily Gann level)
Lesson