re: What is Cosmos 1953?

Walter Nissen (dk058@cleveland.Freenet.Edu)
Thu, 21 Aug 1997 11:14:07 -0400 (EDT)

Leigh, 
I forgot to mention that with C* 1953, like most everything else, much of my 
own observing experience is available to you from URL 
ftp://ftp.physics.ox.ac.uk/pub/sat/info/magnitudes.wn, which I believe has 
now become 
ftp://ftp.satellite.eu.org/pub/sat/info/magnitudes.wn. 
 
It shows that I've seen 1953 glinting as brightly as -2.  This suggests that 
-4 is easily possible.  You'll have to be the judge of whether you think your 
-4 glint is well established based on your memory of how bright Venus is (you 
didn't mention whether or not you were able to see Venus while seeing 1953), 
or whether you think you may have fallen victim to the natural human tendency 
to over-estimate how bright things are (I think there is such a tendency, tho 
I'm not sure anyone has ever tested this) when seen (suddenly?) against a much 
darker background. 
 
The Tselina-Ds were predecessors to the Tselina-2s, whose Zenit rocket bodies 
are among the brightest and most visually interesting satellites. 
 
 
bkh@chem.QueensU.CA (Dr.Brian Hunter) writes: 
 
> Subject: Iridium 4 at -2 magnitude! 
 
> bright object in the northeast.  It is difficult to give a reasonable ... 
> magnitidude -2 is only  a guess for 'WOW that's bright'.  It stayed very ... 
> 01:54:31 +/- 1 second.   The timing is dead on for Iridium 4 ( 97 020E, 
> 24796) and the brightness is typical of the Iridium satellites. 
 
> On August 2, 1997, Leigh Palmer reported an unusual observation ... 
> Within a 
> minute of the prediction for Cosmos 1953, I find Iridium 5 within a few 
> degrees at culmination.  Running Skymap, Iridium 5 ( 97 020D, 24795) was 
> within about 2 degrees of the Cosmos 1953 position a minute earlier.  The 
> only problem with this conclusion is that, if I read Leigh's message 
> properly, is that the timing is now out by two minutes rather than one. 
 
Leigh, can you tell us whether in your opinion the object you saw was more 
likely Ir 5 or C* 1953? 
 
> The observations are remarkably similar. To quote Leigh: 
>              bright, but mag -4 or so 
 
> Sounds familiar.  Furthermore, I have seen Cosmos 1953 10 times and have 
> recorded it as 'naked eye', or 'flasher about 9 seconds'. I've never seen 
> it exceptionally bright or managed to get a good timing of the flashes. 
 
One of the intriguing things about the Tselina objects is that their 
irregular behavior is so very irregular; irregular even for an irregular 
object.  Typically the amplitude (brightness) and the period will both be 
irregular.  Yet at other times the flashing will be perfectly regular. 
How's that for irregularity? 
 
I've seen C* 1953 many times and have seen many passes such as you, Brian, 
describe, and some that are much more like the one Leigh describes.  Many 
of the Tselina objects have been observed glinting (one long flash per 
pass).  I think Leigh may best be able to decide which object he saw, 
perhaps on the basis of the geometry of the pass (position, direction of 
motion, timing). 
 
Another object lesson in the high desirability of astrometric positions. 
Even a single, poor astrometric position (1 or 2 degrees in location, 1 or 
2 seconds in time) can completely resolve uncertainties such as this. 
 
 
Cheers. 
 
Walter Nissen           dk058@cleveland.freenet.edu 
-81.8637, 41.3735, 256m elevation

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Carpe noctem!