Re: OPS 8180 (RADCAT) 1972-076A

From: Ralf Vandebergh (ralf.vandebergh@home.nl)
Date: Mon Aug 09 2010 - 14:49:30 UTC

  • Next message: Makoto Kamada: "Re: What satellite was this?"

    Hereby an additional set of frames from the Radcat session on July 18, all
    taken within 1.0 second of time,
    before any visible rotation becomes obvious. This can be used as a
    frame-check on reliability of detail.
    (The animation, shown before, is a combination of such frame-checks, over a
    period of 5 seconds, to
    to outrule the effect of seeing)
    
    http://tinyurl.com/2wh68ru
    
    
     Ralf Vandebergh
    
    
    
    >
    >
    > > Brian Webb asked:
    > >
    > > > I have two questions about OPS 8180 (RADCAT) 1972-076A:
    > > >
    > > > 1. When this spacecraft was launched in 1972, was there any
    information
    > > > publicly available about it? What did the TRW Space Log say about it?
    > >
    > > I do not know how much information was made public in 1972; the 1987
    > edition of the TRW Space Log
    > > does not name or describe the object.
    > >
    > > > I have the impression that it was an unclassified payload with a
    highly
    > > > specialized purpose that would not have been of much interest to the
    > public.
    > >
    > > I agree; it is a radar calibration target.
    > >
    > > Two Radcats were built; the first one was lost (along with many other
    > payloads) in a launch failure
    > > on 1968 Aug 16 UTC; see Jonathan McDowell's launch log for details:
    > >
    > > http://www.planet4589.org/space/log/launch.html
    > >
    > > The second one was launched on 1972 Oct 02 UTC. USSTRATCOM's catalogue
    > number is 6212. The COSPAR
    > > designation is 1972-076A.
    > >
    > > > 2. Are there any detailed drawings or photos of this satellite
    available
    > on the Internet?
    > >
    > > A drawing appears in the 1971 report, "RADCAT Radar Measurement
    Program",
    > available here, scanned
    > > into a 26 MB pdf:
    > >
    > > http://handle.dtic.mil/100.2/ADA036305
    > >
    > > The drawing is in Figure E-1 on page 241 of the pdf, which I have
    > extracted and provided below:
    > >
    > > http://satobs.org/seesat_ref/misc/72076A_dwg.jpg
    > >
    > > On pg. 240 of the pdf, Radcat is described as, "an 8 foot cylinder with
    > 2:1 oblate spheroidal ends".
    > > Based on the dimensions given in Figure E-1, its overall length is 10 ft
    > (3.05 m), and its diameter
    > > is 4 ft (1.22 m).
    > >
    > > NOTE: The SI dimensions derived from the report, solve a long-standing
    > problem in the R.A.E. Table
    > > of Earth Satellites 1957-1989, which describes Radcat as a cylinder,
    12.2
    > m long and 3.05 m in
    > > diameter. Those dimensions never made sense, and now it is obvious that
    > they arose from some sort of
    > > garbling of information, whereby 10 times the diameter became the
    length,
    > and the length became the
    > > diameter.
    > >
    > > Observed Optical Characteristics
    > >
    > > Russell Eberst has reported 57 observations of Radcat since my
    > correspondence with him began, in
    > > 1989, which I have used to determine its standard visual magnitude, per
    > the following plot of
    > > magnitude normalized to 1000 km range vs. phase angle:
    > >
    > > http://satobs.org/seesat_ref/misc/72076A_std_mag.pdf
    > >
    > > The standard magnitude is 5.7 +/- 1 (1000 km, 90 deg phase angle).
    > Coefficient of phase is 0.017
    > > mag/deg.
    > >
    > > In its present 470 km circular orbit, the object reaches magnitude 3.7
    +/-
    > 1 when observed at high
    > > elevation, and well illuminated.
    > >
    > > The object was steady in brightness in each one of Russell's 57
    > observations. The PPAS record of 18
    > > observations, which spans 1973-2005, is in agreement. The PPAS archive
    is
    > available here:
    > >
    > > http://www.io.com/~mmccants/bwgs/index.html
    > >
    > > Ted Molczan
    > >
    > > _______________________________________________
    > > Seesat-l mailing list
    > > http://mailman.satobs.org/mailman/listinfo/seesat-l
    > >
    >
    
    
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