Strange acceleration of the period of Gorizont 23

Kurt Jonckheere (kjonckheere@mail.unicall.be)
Mon, 22 Dec 1997 22:15:58 GMT

hello all,


One week ago, I observed Gorizont 23,

Now, I did a small analysis on some accurate observations of
Gorizont 23 = 21533 = 91- 46 A

The graph you can find at :
http://uc2.unicall.be/kjonckheere/gorizon.gif

Observers : Jean-Pierre Rohart, Rainer Kracht, Kurt Jonckheere,
Mike McCants, Robert Sheaffer, Ron Lee and Ed Cannon
Date       Period Obs  Day Of Year
07-05-97   53.47  RO
08-05-97   53.47  RK   128
09-05-97   53.46  KJ   129
18-05-97   53.44  MM
26-05-97   53.36  RS
27-05-97   53.37  RGL
29-05-97   53.37  RS
01-06-97   53.40  EC
07-08-97   52.87  MM   219
22-09-97   52.54  KJ   265
16-12-97   51.22  KJ   350


let DP = decrease of period (seconds per Day),
then :

Between May and August : DP = -0.0066 s/D
Between May and End Sep : DP = -0.0068 s/D
When we use a mean value of about -0.0067 s/D
we get for mid Dec expected period of : 51.98 s
Although my measured value was = 51.22 s
(I'm using a stopwatch with multiple lap-times, so
miscounting is excluded)

So between May and the end of Sept 97, the period
was going down linearly, but now it seems to go
down a lot faster !!
What can be the reason for this ?

Who can confirm ?

>From now on the object becomes visible from the East coast of America,
and will be visible for the West coast within a week or so.

Accurate timings are appreciated very much !
The flashes are very brief so on can time a max with an accuracy of
let's say 0.3 seconds, so counting 30 periods already gives
an accuracy of 0.01 seconds on the obtained period.

It is often flashing with maxima of mag +5, but sometimes it just mag +8.5,
so a telescope might be usefull.

>From OIG : 
21533
1 21533U 91046A   97338.83550470 +.00000063 +00000-0 +10000-3 0 00277
2 21533 003.5925 067.0470 0008932 085.8874 273.8954 00.98906082017655

something else :

Ed Cannon  wrote :
>96- 29 B 97-11-16 11:57      EC   55.3 0.5  17  3.25  mag 1.5->2.5?
>For those who don't read flash reports (like I didn't for many 
>months), the period I measured was 3.25 seconds.
>Now here's a NEW observation, from a few hours ago (from Bee Cave
>Research Center Austin location):
>96- 29 B 97-12-22 00:34      EC   56.4 0.3  15  3.76  fAfA mag +1
>
>There's still a problem, maybe, because of the differences in the
>periods (3.25 versus 3.76).  Or maybe that's normal slowdown?  
A decrease of 3.25 to 3.76 in about 5 weeks is indeed a normal slowdown
(although I haven't checked what is normal for rockets like 96- 29 B).


Happy observing !

Kurt Jonckheere (kjonckheere@unicall.be)