Superbird A flashes observed from Austin, TX

Mike McCants (
Mon, 17 Feb 1997 09:37:03 -0600 (CST)

I am at work on Monday morning and I deliberately left
my observing notes at home so that I would not be tempted
to spend an hour or two entering a proper observation
report.  I "promise" to do that this evening.

Ed Cannon and I maintained a continuous watch on Superbird A
from a time of acquisition (02:06UT Feb. 17) until shadow
entry (03:58UT).  The main telescope used was the 12 1/2 inch,
but an 8 inch and 3 inch and 2 inch finder scopes were also

Two "episodes" of bright flashes were observed:  the first
was centered about 02:35UT and the second was centered
about 03:40UT. (Possible memory error up to 10 minutes?)

When first acquired and in between the episodes, Superbird A
had a regular tumble from about magnitude 12 to invisible.
The period was 5.85 seconds.

In each episode, flashes were initially noticed at about 10th
or 11th magnitude and these flashes gradually increased in amplitude
until they became about 4th magnitude.  The duration of increase
was about 10 to 15 minutes.  The flashes were assiociated with
one of the regular 5.85 second tumbles.  Even the brightest
flashes were preceded (by 5.85 seconds) by a tumble to about
12th magnitude and occurred during (in the middle of) such a

The flashes had a 23.4 second period and there were never significant
flashes seen at the half-way time of 11.7 seconds.

One interesting question is:  Was the "phase" of the flashes the
same in both episodes? (Relative to the underlying 5.85 second

However, when shadow entry was occurring about 03:58UT, equally
spaced flashes of magnitude 8 or 9 were seen to occur with a
period of 11.7 seconds.  This is "intriguing".  I definitely
thought that the primary flashes were decreasing in brightness
before shadow entry effects became noticeable, so I was surprised
to see (a few) equal brightness flashes with an 11.7 second period
just before shadow entry.

It appears that someone out west has sent us some thin cirrus clouds
this morning.  Even thin cirrus may prevent observations this evening
since the moon is so bright.

Mike McCants