Next: Rotation Axis Up: Validity study Previous: Validity study

### Introduction

To establish the validity and usefulness of our new method, a so-called blind test was performed. In this blind test, Patrick Wils used the satellite ephemeris program Sat to calculate the times at which the satellite 72- 57 J (the third stage that orbited the Soviet satellites Cosmos 504 to 511) would give off flashes during two consecutive passes on March 6, 1995, for an observer at a northern latitude of degrees and eastern longitude of degrees, assuming that the rotation axis was located at (i.e. right ascension and declination ), that the rotation period was 40 seconds and that the first flash(es) (of each pass) occurred at the first time(s) mentioned in table 1.

Patrick Wils next randomized the results from the ephemeris program to simulate the human reaction time, and thus make the results look more like real observations. The times from the ephemeris program were changed by adding a random number in the range -1.5 to 1.5 seconds for the first pass and in the range -0.5 to 0.5 seconds in the second pass. Those 'randomized' times are given in table 1.

Note that the only information I was given were the orbital elements of 72- 57 J and the data found in table 1. The aim of this blind test was to establish whether it was possible to correctly deduce the direction of the rotation axis and the rotation period of the satellite in question.

It should be remarked that the whole exercise was academic, the object 72- 57 J does, in reality, not give off flashes, and the input data are fictional. However, since an independent determination of the rotation axis of a satellite that also gives off flashes in reality is lacking, the above was the only way to rigorously test the method. We chose to perform the test in a blind fashion, to ensure that our results are not tainted by the subjective interpretation inherent in analyzing the results.

Table 1:  Times (in Universal Time, UT) of flashes for pass 1 (left) and pass 2 (right) of 72- 57 J on March 6, 1995.

Next: Rotation Axis Up: Validity study Previous: Validity study

bdp@mpe-garching.mpg.de