Hi All, Finally got a chance to look for the TDF-1 GEO flasher (#19621) Sunday evening (Aug 22) from Newport Coast, CA. The gibbous moon was not far away; fortunately TDF-1's flashes were plenty bright -- at least magnitude +2. Since I didn't see the beginning of the sequence, I don't when the center of the flash window was. Flashes were visible from 22:40 PDT (5:40 UT, 23 August) until at least 22:55. Some of the brightest occurred from 22:45 to 22:49. The basic period seems to be about 29.666 (+/- .003) seconds, though equally bright flashes are seen on the half-period. When I first acquired TDF-1, it was doing "double flashes" at each half-period. The double flashes were about 1/4 second apart. Later on, the doubles reduced to singles. So while this satellite is similar to Superbird A (#20040) in terms of approximate period and flash brightness, its flashes are more complicated. PPAS report for TDF-1 (19621, 88098A): 88- 98A 99-08-23 05:52 RM 237.33 0.05 16 29.666 mag +2 -> inv