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
This archive was generated by hypermail 2b29 : Fri Aug 06 2010 - 15:37:20 UTC
