Re: Primary and Secondary Flashes

Ron Lee (
Sun, 03 Oct 1999 09:15:28 -0600

At 10:16 AM 10/3/99 +0200, you wrote:

>I haven't seen it myself yet, but from all accounts the secondary flashes
>become brighter, and the primary fainter.
>Then the primary flashes more or less disappear, and you have again a 23
>second period.
>But the latter series is shifted 11.5 seconds wrt. the first,
>and the transition, "phase shift", is important for the
>determination of the rotational axis.

I would clarify this a bit in that during the few minutes around the 
"phase shift" both flashes are about equally bright....THEN the first
surface flashes become dimmer while the initially faint flashes are 
now bright.

My obs of a few nights ago showed a less pronounced middle section..
both flashes equally bright...than I am used to.  

Ron Lee