X-Ray Intensities and Spectra from Several Cosmic Sources

Abstract

This paper reports the results of X-ray spectrum and intensity measurements for several cosmic X-ray sources. Two flights were conducted, one from Kauai, Hawaii on July 28, 1966, and the other from Johnston Atoll on September 20,1966. Proportional counters with anticoincidence shields to eliminate charged-particle background counts were used to detect the X-rays. Four known sources were observed: Sco XR-1, Tau XR-1, Cyg XR-1, and Cyg XR-2. Total intensity determinations were made for all of these sources, and spectra were obtained for Sco XR-1 and Cyg XR-2. A search was made for X-rays from the Large and Small Magellanic Clouds, but no X-rays above background were found in that region of the sky. An upper limit of the X-ray intensity from the Magellanic Clouds has been determined from these data. A weak X-ray source not previously observed was found in the constellation Vela (Vel XR-1).