Re: Flaring GEOSAT Observation Success

Ron Lee (
Wed, 06 Oct 1999 08:58:14 -0600

I started the process based upon Rainer Kresken's posting.
I ran Skymap (Rob Matson's) to find where GEO's entered the
earth's shadow.  Amazing how many are inclined and sweep 
south of the center of the umbra this time of year.  Anyway,
I eventually figure out what satellites to expect as well as
when and where.  

I printed out a chart in Az/El mode without satellite tracks
and one with two representative satellites.  Then set up the 
lawn chair, clipboard, pen, red flashlight, stopwatch, and
tape recorder (for Superbird) and locate the area.  Spent a few
minutes memorizing star patterns so any "new star" would be
easy to spot.

Then I noticed flashing towards the horizon.  I saw several
flashes that suggested it was not an airplane then tried to reset 
my stopwatch.  That took longer than most coordinated folks 
would take and by the time I returned to the spot...the flashing
had ended.  An approximate position is RA 00:53  (h:m) and 
DEC -09:17 (D:M)  (J2000) at 0201 UT on 6 Oct 99.  The position
error could be high since I did expected to see it again while
making flash timings.  I found no match in GEO.TLE or ECCEN.TLE.

As an aside, this session started out with the target area 
perhaps 15 degrees above the horizon and at a local STANDARD
time of 7 PM.  I am currently at UT-6 hours but on daylight
savings time so the session started at 8 PM DAYLIGHT SAVINGS

After several minutes trying to recover the flasher, I gave up
and returned to the target area and saw TWO (2) GEOs flaring
in very close proximity to each other.  This was 02:11 UT and
I believe they were two of the following three (in order):

#23764/96002A/PAS 3R
#24891/97040A/PAS 6
#25585/98075A/PAS 6B

My guess is that it was #24891 followed by #25585 but I would need
to see them again..perhaps in a telescope to find the third... to
know for sure.  The easternmost one was the brighter of the two,
perhaps by two magnitudes.  All these obs are in 7x50 binocs with
a limiting magnitude of 8.5-9. These were easily seen so possibly
in the 6-7 magnitude range.  RA/DEC at 02:11 UT was 00:40.3 and
-05:45   (hh:mm.m and dd:mm respectively J2000).  Penumbral entry
was right after this and occurred while I was looking at my chart,
hence not observed.

As another aside, I considered using the 8" telescope to observe
these events but in retrospect, the binoculars allowed seeing
the satellites over a wider area.  A telescope would have picked
up more but I would not have seen them as early.

Next was #22314/93003B/TDRS-6. First recorded position at 02:21 UT
at RA/DEC  00:34.6 and -06:26.   Last obs at 02:29:30 UT at RA/DEC
00:43.1 and -06:27.  This object brightened as it approached the 
penumbra and the last obs was perhaps one minute into the shadow.
At 02:30:30 it was faint and was gone when I last looked at 02:30:45.

Observing note:  The first recorded obs/position was typically a few
minutes after I first spotted it.  It takes a little time to verify
motion relative to the stars and to get to a good reference point.

The fourth GEO was #23915/96035A/Intelsat 709.  First recorded position
was at RA/DEC 00:32.3 and -05:45 at 02:31:20 UT.  It was gone by 02:40 UT
and disappeared while I was not looking.  Penumbral entry about 02:38 UT.

The fifth satellite was #23571/95023A/Intelsat 706.  First recorded
position at 02:42 UT was 00:30.3 and -05:48.   Last position was at
00:34.3 and -05:46 but I failed to record the time.  Penumbral entry
about 02:50 UT.

Sixth satellite was #24916/97046A/PAS 5.  At 03:03 UT it was at RA/DEC
00:29.8 and -05:50.  Last obs at 03:08:45 UT was at 00:35.5 and -05:50.
Penumbral entry about 03:10 UT. It was not observed but it was not seen
when I looked at 03:12:50 UT. 

Last satellite observed before I tried Superbird was #25004/97059A/
Echostar 3.  First obs at 3:08 UT at 00:19 and -05:53.   Last obs
at 03:23:30 UT at 00:35 and -05:53.  This was was unique in that it
was brightest at the beginning then faded as it approached the shadow.
It was seen several minutes before the recorded first obs since I was
waiting for it to get near better stars for the position.

I am not familiar with the structure of these satellites but there are
several PAS objects.  In general, they did get maybe a magnitude brighter
as they approached the penumbra.  All were easy in binoculars but only
one or two MIGHT have achieved naked eye brightness.  (I did not make
an attempt to assess absolute brightness).

Overall, this was a great experience.  It has been something I assumed
would be possible but until Ranier suggested it, I never tried it.
Supposedly, the viewing gets better for my latitude.  I am also 
assuming I could have watched GEOs do this all night...that it is not
limited to around local sunset/sunrise.

If clear tonight, I will try to find the UNID flasher and perhaps look
for the three PAS satellites that are close together.

Ron Lee