UNID Geosync oddball

Eric Vondra (evondra@usaor.net)
Sun, 06 Jun 1999 01:54:51 -0400

My brother, an experienced observer,  made an unusual observation
from Pittsburgh (40.4N 80W, 380m) at 0100 UT June 6. In bright
twilight, he casually looked up after getting off the bus and a
bright "star" caught his eye at approx. azimuth 240, declination
+5-10 deg. (below where Regulus should have been, but the sky was to
bright to locate Regulus--only 14 min. after sunset). It was -3 mag.
for about 1 to 1-1/2 minutes then dropped instantaneously, as if it
were a light bulb being switched off, to the naked eye limit (maybe
2nd mag. in that sky?) for about 10-15 seconds, then faded
gradually. He was observing with the unaided eye only. It looks like
Gorizont 23 was in the area, but I don't recall anyone seeing this
kind of behavior from it. Is it possible for a geosync to produce a
sustained glint that bright? Sorry he couldn't be more specific as
to the exact location, but the sky was too bright to see much else.
He checked motion against a light pole and determined there was none
discernible to the unaided eye. He is a very experienced amateur
astronomer and has been observing satellites frequently since the
GSOC site went online.

Could this have been Gorizont 23? Any more likely candidates? I was
even thinking it might have been a plane coming straight at him, but
he would have been able to see the aircraft itself or its other
lights (his eyesight is extremely good) and would have heard it
(also, at that elevation, 30-40 degrees up, it would have to have
been just about diving to be heading straight towards him). The sky
was clear but with some thin cirrus. No thick clouds present that
could have suddenly obliterated the view (and it was plenty bright
to see any).

(By the way, he also observed STS-96/ISS/Starshine the morning
before and saw Starshine flash four times, brightest to about 0
mag., preceding the Orbiter).

Eric Vondra
Wampum, PA, USA