Obs of object called USA 144 - tumbling?

Mike McCants (mikem@freeside.fc.net)
Wed, 9 Jun 1999 15:58:16 -0500 (CDT)

I was able to watch the object called USA 144 for a little while
last night.  It was close to on time compared to the prediction
below.

It was only about 5th magnitude at maximum, implying an intrinsic magntude
of only about 6.  This seems much too faint for what should be quite
a large payload.

I have seen one of the big spinning payloads in the past and one thing that
was remarkable was the "square wave" light variation seen.  In other
words, if the object was spinning around its long axis and it had
stripes of white and black paint running lengthwise along that
axis, then sunlight would alternately strike a white stripe and then
a black stripe.  There were very sharp increases and decreases in brightness
that could be described as a "square wave".   A square wave with a
one second period might indicate 4 pairs of alternating white and
black stripes and a true spin rate of 4 seconds.

On the other hand, a tumbling object will usually show more gradual
changes in brightness (unless there is a sudden increase/decrease
in the specular component of the brightness).

The object I saw last night seemed to be a rather small piece of
tumbling debris.  I would guess only 1 or 2 meters in size.
The brightness ranged from about 5th magnitude at max down to
something close to 8th magnitude.  In general, it was faint quite
a bit of the time, increasing to 5th or 6th magnitude for a second
or two about every 8 seconds.  The tumble did not seem perfectly
regular.  At one point I believe that two maxima occurred fairly
close together.  One rather faint (mag 6?) "flash" was observed.
The instrument used was a 12x80 telescope.

  30.315  97.866  920.   Bee Caves Rsrch Ctr

1999 June  8  Tue evening  *** Times are PM CDT (UT-5)

25744 USA 144                            6.0
 H  M  S  Tim Al Azi C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec
10  0 55   .0 59 240 C 267  5.1   1 4  245  80  283 2.9  85 1149  12.0
10  1 15   .0 54 210   241  5.0   1 4  245  54  298 3.0  69 1231  -2.0
10  1 34   .0 45 191   226  5.2   1 4  245  27  336 2.8  57 13 6 -13.9

USA 144
1 25744U 99028  A 99159.07478761  .00062000  00000-0  71960-3 0    00
2 25744  63.4100  42.4565 0010000 349.9893  10.0106 15.61344808    08

Mike McCants
Austin, Tx