Engineering topics
Publications and source records attributed to Garmire, G..
The soft X-ray intensity, spectrum, and variability of Sirius as determined with the HEAO A-2 experiment are reported. The X-ray spectrum of Sirius is shown to be extremely soft, and an upper limit of 200,000 K is established for the temperature of the emitting plasma. Observational constraints on models of coronal emission from a hot envelope surrounding either Sirius A or Sirius B are briefly considered
Observations in outburst of two dwarf novae, SS Cyg and U Gem, reveal soft, pulsed X-ray emission greatly enhanced over the emission present during the quiescent periods. In order to characterize the nature of the X-ray pulsations a random phase analysis was carried out, which indicated the phase of SS Cyg behaved like a random variable with zero mean and an r.m.s. value that increased with the square root of the time. Attention is also given to the properties of the detected dwarf novae during optical quiescences, to isolated white dwarfs, and to optical observations of AM Her. It is concluded that the dwarf novae, which occur in binary systems, appear to be controlled by the varying accretion of matter generated by the main sequence companion, and that the X-ray emission during outburst appears to consist of two separate components: a periodically varying (on about a 10 s timescale) soft component, together with a more slowly randomly varying hard component.
HEAO 1 observations of soft X-ray emission from a point source in the vicinity of Alpha Cen are reported. The source, designated H1437-61, is tentatively identified with Alpha Cen, and an X-ray luminosity comparable to that of the sun in an active state is estimated. A temperature of about 500,000 K and an emission integral of 5 x 10 to the 50th per cu cm are obtained. Coronal emission is suggested as the X-ray-producing mechanism.
A soft X-ray spectrum of Capella has been obtained with the HEAO 1 satellite. Only models which include intense line emission at 0.85 keV can adequately explain the data. The spectrum is consistent with emission from an isothermal solar-abundance plasma with a temperature of 10.5 million (+ or - 2.8 million) K. It is also consistent with a blend of temperatures between 4 and 20 million K. The intensity of the X-ray emission is constant over 2 days and similar to the intensity observed by ANS.
The HEAO-1 A-2 experiment, designed to study the large scale structure of the galaxy and the universe at X-ray energies is described. The instrument consists of six gas proportional counters of three types nominally covering the energy ranges of 0.15-3 keV, 1.2-20 keV, and 2.5-60 keV. The two low energy detectors have about 400 sq cm open area each while the four others have about 800 sq cm each. Dual field of view collimators allow the unambiguous determination of instrument internal background and diffuse X-ray brightness. Instrument characteristics and early performance are discussed.
Low- and medium-energy X-ray observations of Cen X-3 during two pointed sounding-rocket experiments are discussed. The lack of low-energy emission from Cen X-3 is consistent with the identification of Krzeminski's star as the optical counterpart of Cen X-3 and normal reddening, in contrast to an earlier measurement by Bleeker et al (1973).
Cen X-3 was observed twice. A pulse profile and spectrum was obtained in the 2- to 10-keV band, but no soft flux was detected. Vela X-1 was observed to have a rapid flickering characteristic on time scales down to 0.25 sec and a hard spectrum. The source 3U 0614+09 was observed and found to have a softer spectrum (kT of about 4 keV) and an intensity comparable to that of earlier observations. The source eta Car was not detected at a level of 0.03 ph/sq cm/sec in the band from 0.2 to 1.5 keV, and the Large Magellanic Cloud was observed in the band from 0.5 to 1.5 keV at a level of about 0.1 ph/sq cm/sec. Two soft extended regions were observed in Gem-Mon and Eridanus.
Data are presented from two experiments to demonstrate the effect of electron contamination on X-ray measurements within the magnetosphere. The data are taken from a rocket flight which detected auroral X-rays in the energy range from 2 to 10 keV and from Uhuru measurements of the magnetic field-modulated electron flux. It is shown that the level of electron contamination rendered the rocket observations completely unreliable, but profiles of the charged particle flux as functions of terrestrial longitude were able to be obtained from the Uhuru data. It is stressed that particle contamination of X-ray data will occur even near the equator at high electron threshold energy. Corrective measures are proposed to eliminate the contamination or to reduce or evaluate the effects of such contamination.
The HEAO A-2 experiment is described which is designed to observe the spectral and spatial structure of cosmic X-radiation over the entire sky with the minimum sensitivity and cross checks required to achieve a number of objectives. Developments in X-ray astronomy are discussed which are relevant to the experiment, including setting a lower limit on the number of discrete sources contributing to the background flux, determining the spatial dependence of the flux, observations of the spectral components of discrete sources, and the study of X-ray absorption by interstellar gas and the atmospheres of binary stars associated with pulsating X-ray sources. It is shown that systematics-free measurements will be made by making simultaneous observations of single sources with several detectors, by using two-layer detectors to eliminate the effects of electron contamination, and by incorporating magnets into low-energy detectors to minimize electron contamination.
The Vela pulsar PSR 0833-45, located in the Vela X nebula, has the second shortest period of any of the known radio pulsars. Soft X-ray observations are described which place an upper limit of 0.3% on the pulsed fraction of the Vela pulsar relative to the flux from the entire Vela X Nebula, in the 0.5- to 1.0-keV energy band. The present results are about a factor of 7 below the value of 2% measured by Harnden and Gorenstein (1973) for the pulsed fraction relative to the flux from the Vela X Nebula.
An X-ray position detector for real time operation is described. A set of proportional counters is arranged into an array which can detect and indicate the position of an X-ray interaction within the array, in the X Y plane.
Observations of cosmic X-rays in the energy band 0.2-3.0 keV were made from an experiment on board an Aerobee 170 rocket launched from White Sands, N.M. on Dec. 19, 1970. A survey along the galactic plane between the Crab Nebula and Cygnus provided data on the interstellar absorption and X-ray flux for the Crab Nebula, NP 0532, Cas A, and Cyg X-2; upper limits were obtained for the flux from a number of supernova remnants. The 1/4 keV X-ray background was measured over a limited range of galactic latitude and longitude.
Seyfert galaxy NGC 1068 IR observations, noting angular extent and size
IR object Maffei 1 observational data indicating highly reddened giant elliptical galaxy of Local Group
Nebula K3-50 IR radiation source observation, noting energy distribution resembling NGC 7027 and W51-IRS 2
Photoelectric spectrum scanning and IR photometric observations of Scorpius XR-1 X ray source
Systematic analysis program for proportional counter X ray spectral observations of celestial objects, considering interaction between radiation field and detector
Modulation collimators determining angular sizes and celestial positions of X ray sources Sco X-1 and Taurus XR-1