Re : Gorizont 23 not seen, Raduga 27 seen!
Jason Hatton (Jason.Hatton@unice.fr)
Thu, 22 Jul 1999 09:47:22 +0200 (MET DST)
Kurt Jonckherre wrote;
> When I was moving my scope to the position of Gorizont 23 on Sunday,
> I suddenly noticed a short flash about 1 degree before Gorizont 23.
> After more than a minute (so more than Gorizont's 50 seconds) another
> flash was noticed and so on...
> I checked the predictions and immediately saw that Raduga 27 = 91-14 A
> = 21132 was back, after Jason Hatton "lost" it about one month ago
> because too faint. It was flashing clearly to mag +8.
> More observations (from other places) are needed to find out how the
> rotation axis is behaving.
> [Observation made from Ostend, 2d 55m E, 51d 22m N].
>
> In contrast with Gorizont 23, which has been accelerating with a perfectly
> linear rate, the acceleration of Raduga 27 slows down (see the data
below).
> The flashing period was going down with about 0.39 s/day during May,
> 0.30 s/day during June and now with about 0.23 s/day.
Unfortunately, I hadn't been able to verify whether Raduga 27 had started
flashing again after I lost the flashes since the slow westward progression
of this satellite across the sky has put into a place where it is
impossible to observe from my apartment (& haven't had the possibility to
observe from another site in the meantime)
I wonder whether the dissappearence & reappearance of the flashes are due
to the changing solar declination, rather than a precision or shift of the
spin axis? When I last saw flashes the sun was close to its most northerly
declination, but now it is moving south again. So the change in solar
declination would cause a change in sun-satellite-observer angle with a
corresponding shift in the flash track on the earth. This effect could also
explain why Gorizont 23 is currently invisible. Last year I remember
Gorizont 23 being very bright during February, but much fainter during the
summer.
I did note that the flashes faded in brightness from approx. mag +5 to +9
over the 5 week period I observed the satellite. So, it will be interesting
to see if the flashes brighten of the next weeks - if so this might support
the hypothesis of that the flash path across the earth varies in proportion
to the declination of the sun. So again more observations (including
negative observations) would be welcome.
Thanks also to everyone who posted reports on the flash characterisitics of
the Okean-O rk (99-39B). I had a good pass last night (culmination at
20:10UT, 21st July 1999). Even from the hazy light polluted skies of Nice
it was an easy naked eye object flashing to mag 0. Flash period is approx.
0.6s (I have exact timings at home) & occasionally it appears to miss a
flash. Very nice to be able to make a flash timing without having to use
binoculars or a telescope!
Best wishes & clear skies,
Jason
43.692N, 7.246E,30M
(43d41'29"N,7d14'47"E,30m)
http://www.geocities.com/CapeCanaveral/Hangar/1668/high-alt.htm
---------------------------------
Jason Hatton
INSERM U 343
Hopital de l'Archet
Rte St. Antoine de Ginestiere
BP 79, 06202 Nice Cedex 03
France
Tel(33)-4-92-15-77-00
Fax(33)-4-92-15-77-09
email : hatton@unice.fr
43.667N, 7.223E, Alt 30M