Unusual brightness of 96072B Titan 2nd stage

Ted Molczan (molczan@fox.nstn.ca)
Tue, 31 Dec 1996 11:49:55 -0500

Tony Beresford's observation of 13:47 UTC on 31 Dec 96
upholds the std magnitude of 2.1 that I estimated from
his and Rob McNaught's reports of 30 Dec. Prior observations
supported a std mag no fainter than 3.  So this remains
a very bright object, exceeded only by Mir (1.6) and shuttles
(0.8), to the best of my knowledge.

For about the past year, I have been using a std mag of 4.82
for Titan 4 2nd stages, based on Rainer Kracht's analysis of
Russell Eberst's numerous accurate observations of 91017B. He 
also analyzed 91076B, and obtained similar, though slightly 
fainter results.

So it seemed reasonable to assume that all such objects would
be essentially std mag 5 objects. But the extreme brightness
of 96072B requires that this be revisited, so I asked Rainer
to update his study to include the 2 Titan 4 stages observed
earlier in 1996: 96029B and 96038B; all by Russell Eberst.

He has kindly done so, and the results, tabulated below, are 
very interesting. These newer objects are considerably 
brighter than 91017B 91076B. This morning, I added 90050E to 
the picture, based on 19 obs, all by Russell Eberst. On 
average, I found that it was about as bright as 91017B and 
91076B.

So these objects are not all alike. I would not place too
much importance on the apparent trend to increasing 
brightness, because the sample of 6 objects is rather small.


Object   State    Obs  Std Mag  Payload
------  --------  ---  -------  -------
90050E  flashing   19   4.67     NOSS

91017B  flashing  124   5.14     Lacrosse
91017B  steady    494   4.82

91076B  flashing   52   5.33     NOSS

96029B  all        87   3.74     NOSS

96038B  flashing   28   3.50     SDS

96072B  steady    <10   2 to 3   KeyHole

 
One additional avenue of inquiry was suggested yesterday
by Allen Thomson:

>   I wonder if pictures of the booster before or during launch would
>shed any, ah, light on the matter. IIRC, such pictures have been
>released for most T-IV launches.

I believe this is worth following-up. I would like to compare the
"paint-job" on these objects.

Clear skies and Happy New Year!
Ted Molczan