Superbird A; Colorado; 18 Feb 97, Long Report

Ron Lee (
Tue, 18 Feb 1997 10:23:11 -0700 (MST)

Flashes again observed starting about 03:38:39.77 UT
Flash interval 23.4 seconds.  Brightness seemed to
fluctuate but noted that the flash at 03:49:11.16 UT
was really bright (relative to others).  These flashes
were not as bright as the 02:35 UT set.  Flash period
from this set is 23.386 +/- 0.007 second.
Last flash recorded was 04:03:13.14 UT about the time
of shadow entry.

Shadow exit flashes seen at about 04:49.6 UT but was not 
observing prior to that.   During the interval, the less than
11.7 sec period flashes were more obvious.  The flashes 
"seemed" to be less distinct, that is, a longer duration.
Estimated brightness of flash at 05:11 UT was 10 by comparison
to surrounding stars and reference to GUIDE 4.0 database.

Observed until 04:36 UT to see if another set of bright flashes
was visible: but none detected. 

I had hoped to get a better period by using flash timings
extending over several hours.  However, the shifting of the 
bright flash between arrays makes it difficult.  My assumed
errors can build over the course of an hour to equal about
11 seconds, thus masking a shift.   Someone with a larger
telescope might be able to maintain visibility when I
cannot and thus determine a more accurate period than I
have provided thus far.

I am also curious as to the usefulness of this info in
analyzing the satellite orientation.  Would a clearer
description of the brightness ramp-up/down be more
useful.   If so, even there it is somewhat subjective.
Determining the mid point of the 02:35 UT flashes was
done last night using the shift in the brighter flash
(between any two spaced at 11.7 sec).  Last night that
point may have been missed while attempting to observe
the satellite visually.

Other details:  Used an 8" scope with 40 mm eyepiece.
May need to shift to a 25 mm to improve obs.  Limiting
magnitude with a gibbous moon nearby was about 12.
useful magnitude for flash timings was 11-11.5.
Timing accuracy assumed 0.4 sec for time between any
two flashes (0.2 sec for any one time).  Occasionally,
slightly higher errors occur due to later than usual

Ron Lee