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Goddard, R.

Publications and source records attributed to Goddard, R..

Uniformity and transmission of proportional counter window materials for use with AXAF

The X-ray detection system used to calibrate the Advanced X-ray Astrophysics Facility (AXAF) mirrors will include gas flow and sealed proportional counters. To meet the ultimate 1 percent goal of the calibration project, the transmission and uniformity of the windows must be well known for the soft X-ray wavelengths involved. Various window materials for use with proportional counters are examined for transmission at X-ray wavelengths in the range of 0.1 to 5.9 keV. These include the usual window materials (polypropylene and beryllium), as well as materials only recently employed for detector applications (polyimide and diamond). The transmission uniformity of beryllium at 1.49 keV is examined with a microchannel plate detector, producing a 'shadowgraph' of the window material illuminated with soft X-rays. This technique allows us to investigate nonuniformities on a spatial scale of about .2 mm.

Flanagan, K.

The SAS-A aspect system

On Dec. 12, 1970, the United States Small Astronomy Satellite-A was launched into orbit around the earth. The X-ray instrument carried by the spacecraft was the first satellite instrument to be devoted exclusively to the study of stellar X-ray sources. The primary objective of the instrument was to perform an all-sky survey to detect and locate stellar X-ray sources with location accuracies of one arc-minute for the stronger sources. A system description is given together with details of circuits, alignment procedures, and calibration sequences.

Jagoda, N.

The UHURU X-ray instrument.

On Dec. 12, 1970, the UHURU X-ray observatory was launched into equatorial orbit with the prime mission of conducting an all-sky survey of astronomical X-ray sources with intensities of 0.00005 Sco-X1 or greater. The X-ray detection system contains 12 gas-filled proportional counters, 6 behind each collimator. The aspect system is discussed together with the structure, the pulse height analyzer, the command system, the calibration system, and the power distribution system. Pulse shape discrimination circuits used on UHURU use the same technique that was used on the system originally developed for large area proportional counters described by Gorenstein and Mickiewicz (1968).

Jagoda, N.

The Uhuru star aspect sensor.

Description of the star sensor used in the spin-stabilized Uhuru satellite for the purpose of detecting and locating stellar X-ray sources. The star sensor had the capability of detecting fourth-magnitude stars to within 1 arc minute of azimuth and 2 arc minutes of elevation. This was achieved with the aid of a slightly modified 76-mm, f/0.87 Super Farron lens, an 'n' shaped reticle located in the focal plane, and an RCA CF70114F photomultiplier serving as the detection element. The star sensor is composed of three major components - a high-voltage power supply, the photomultiplier, and an amplifier.

Jagoda, N.