[Graphs and data on request; DSat allows attachments, but has a size restriction] I observed #27006 on Aug 4 on a pass from near zenith, and noticed a more complex flash pattern while it descended in the SSW. 61 flashes were timed, over 269.46 seconds. Near zenith, there was a slightly fainter half-period maximum, low in SSW both maxima were quick doubles, or even one double + one triple. I tried to time several of the secondary maxima, and used my SYNODIC program to visualize the differences between click times and expected peak times of an assumed constant period. However, they did not stand out among the noise of observational inaccuracy, and I had no tape or visual notation on which clicks were secondaries. There was also a different period, as I have frequently observed on Zenith-2 rockets with short periods. I was not able to find a single transition between the two, or even find reliable intermediate periods during the transition. Of course the rotation period IS constant during the pass, but presence of multiple flashing surfaces, and the curvature of the rocket cylinder, will cause synodic effects. So, it is important to time flashes at different elevations, and especially in both E and W passes, since the size and direction of the effect will differ. On Aug 6 I observed an earlier (E) pass with 43 flashes over 208.05 seconds, but clouds prevented observing the rising. The double and/or triple maxima were again obvious, and I decided to time the minima, which were sharper. In fact, with no deliberate action on my part, it turned out that only one click out of 43 minima was on the half-period ! In 01-56F1.gif there appears to be a longer period (2.993 s) on 08-04 in cycles 3-17, and a shorter period from about 34 (possibly also 0-3). Primary flashes are about 1.5 s above (after) the secondaries (depending on the choice of bias) 01-56F2.gif shows the final (2.865 s) period on primary and secondary flashes, and some hint on the double flash below the lower (secondary) flashes in cycle 85-94. There may however be a longer period in cycles 64-70, just as 0-18 could be (mis-?)taken as part of a 2.865 s cycle. 01-56F3.gif is from 08-06 (minima were clicked). Only at cycle 38 was a secondary minimum clicked. Very little evidence of synodic effects. If you have, or acquire a stop watch with 30+ lap/absolute memories (mine is 100), or a PDA with a stopwatch program, you should record as much as you can. Spread them out over the pass, but include a few bursts of every flash, some every third and/or every tenth, but exact counts are not necessary when using the SYNODIC method. But if you time different kinds of peaks, a note on which they are is very helpful. Note that recording n flashes generally increases the accuracy by a factor of sqrt(n-1), and with least-squares or visually determining the period, the PPAS statement "The number of periods counted. The total time divided by the number of periods gives the flash period" is rarely true. 01-056 F 02-08-04 21:16:25.0 BPG 40.3 0.3 14 2.994 A'aA' 01-056 F 02-08-04 21:20:01.4 BPG 144.5 0.3 50 2.865 A'aAaaA' 01-056 F 02-08-06 20:38:40.5 BPG 208.1 0.3 72 2.896 Aa,AaAa, -- bjorn.gimle@tietotech.se (office) -- -- b_gimle@algonet.se (home) http://www.algonet.se/~b_gimle -- -- COSPAR 5919, MALMA, 59.2576 N, 18.6172 E, 23 m -- -- COSPAR 5918, HAMMARBY, 59.2985 N, 18.1045 E, 44 m -- ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Wed Aug 07 2002 - 12:02:22 EDT