X-ray Observation of Cen XR-4 and Nor XR-2

WE wish to present the results of an X-ray astronomy experiment conducted from a Centaure rocket launched from Thumba Equatorial Rocket Launching Station (TERLS), India, at 0035 UT on December 7, 1969. The detector consisted of a xenon-methane proportional counter of useful area of 55 cm 2 with a 18 mg cm −2 thick beryllium window and a slat collimator with a field of view of 7° × 15°. It had a resolution of 20% for 6 keV X-rays from a 55 Fe radioactive source. The rocket aspect 1 determined from onboard magnetic and Sun sensors showed that it had a spin rate of 5.5 r.p.s. and a precession with a half cone angle of about 3° around an axis centred at R.A. 8 h 56 m ± 4 m and declination 3° ± 1°. The X-ray data were pulse height analysed into three contiguous energy channels in the energy range 2–18 keV.