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

Abstract

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 cm² 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 ⁵⁵Fe radioactive source. The rocket aspect 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.