Re: Bright Passes Obs for Rosat and Topex
Walter Nissen (dk058@cleveland.Freenet.Edu)
Fri, 17 Oct 1997 11:22:31 -0400 (EDT)
Don Gardner, fn470@cleveland.freenet.edu, writes:
> Some reflected light in the visible range probably wouldn't
> affect efficency too much.
Solar panels are highly reflective in the visual, much like a mirror. But
hopefully most of the reflected sunlight is pointed directly back at the
Sun.
> I don't believe that Rosat or Topex have mirror ar the Iridiums and DMSP
> sats have. Any thoughts as the the cause?
Many sats have solar panels. I believe bright double flashes from various
NOAA sats were reported here long ago.
QuickSat (I don't know what you are using) assumes a roughly textured,
smooth sphere. Payloads vary quite a bit from this model. They are
shinier, boxier, and more shadowy. It is a bit surprising that QS's
indicated magnitudes are as close as they are. Most sats have bright
metal parts which can flash if they assume the appropriate attitude to
irradiate your eyes with sunlight.
ROSAT = 20638 = 90- 49A and TOPEX = 22076 = 92- 52A are getting along in
age. Perhaps they have lost attitude control and are tumbling out of
control? When TOPEX was operating (still is?), it pointed its large flat
reflective surface directly down at the Earth, which led to a (very?)
unusual situation. It was spotted glinting brightly, tho not as brightly
as you report, if I recall correctly, at extremely poor phase angles, when
one might have thought it would be virtually invisible. (If you are
looking for records of my experience in viewing bright objects, AltaVista,
given "Nissen and spacewarn and host:gsfc.nasa.gov", will pop up bulletins
469, 490 and 513. If you want fainter objects, too, longer lists are
still available by ftp).
Probably you caught especially bright glints. From what structure, I
would find difficult to say. It will be interesting to see what others
can see.
Cheers.
Walter Nissen dk058@cleveland.freenet.edu
-81.8637, 41.3735, 256m elevation
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