Re: Superbird A observed in Torrance

Ron Lee (ronlee@pcisys.net)
Tue, 10 Mar 1998 21:38:16 -0700

At least you got a good time Rob.  I went out with my 7x50 binocs,
located what I thought was the star field, then was confused why I was not
seeing flashes....OOPS, wrong stars.  I quickly found the right ones but
was about 30 seconds past the predicted peak.

I did notice last night that the flashes were only visible in my 8" about
4 -5 minutes prior to the peak.  Some past sessions the visibility was 
much longer.  Obviously the moon played a part but it still seemed a bit
short compared to previous telescopic obs.  

I noticed Mike's period was about 0.2 second faster than a year or so ago.
Seems it has accelerated slightly.   The phase shift that Rob mentions
below is visible in binoculars. I typically record the bright/faint flashes
on a tape recorder, then come back inside and record it on paper. That allows
me to follow the bright/faint sequence before and after the maximum period
to help define the mid point.

As a question to Rob,  I am not sure of our previous standard.  Do we define
the mid point where the phase shift occurs, or the brightest flash around that
time?  The difference may be only about one period...the impact on Rob's 
analysis unknown.

Ron Lee



At 07:14 PM 3/10/98 -0800, you wrote:
>Hello all,
>
>Just went out to observe Superbird A (#20040) in exceedingly clear skies.
>If it weren't for the nearly full moon only 11 degrees away, the flashes
>would have been visible with the unaided eye.
>
>I observed flashes with 8 x 56 binocs from 2:45 UT to 2:53 UT, 11 March
>1998.  Peak flashes were right at the predicted time (around 2:48:30 UT).
>1 minute either side of the peak, flashes were also visible on the half-
>period.  Phase transition took place about the time of the peak, with the
>previously dimmer odd half-flashes overtaking the brighter even half-flashes.
>The even half-flashes subsequently dimmed so that only the odds were
>visible.  This is the typical behavior that we've noticed in past years.
>
>I did not have a stop-watch handy, so was not able to time flashes.
>However, I do have a good estimate of the peak brightness -- about 3rd
>magnitude.  Flashes were about twice as bright as the nearby 3.90-mag
>star HD#083618, which was in the same field-of-view.
>
>Of course, flash magnitudes are quite subjective, and estimates will vary
>from individual to individual.  I've noticed that my estimates always seem
>to be brighter than "the mean," so perhaps my eyes/brain have a fast
>integration time!  ;-)   --Rob
>
>