We present the calibration and background model for Proportional Counter Array on board Rossi X-Ray Timing Explorer. The energy is systematics-limited below 10 keV, with deviations from a power-law fit to Crab Nebula plus pulsar of less than 1%. Unmodeled variations in instrumental amount 2% observed keV 1% between 20 keV. Individual photon arrival times are accurate 4.4 μs at all during mission 2.5 after 1997 April 29. peak pointing direction five collimators known precision few arcseconds.

The proportional counter array (PCA) is designed to perform microsecond timing of bright galactic sources and broad band, confusion limited, studies faint extragalactic in the 2 - 60 keV x-ray band. PCA was launched as part Rossi X-ray Timing Explorer (RXTE) satellite into a circular orbit altitude 580 km 23 degrees inclination on December 30, 1995. mission contains three experiments: set large area xenon counters sensitive from (proportional array: PCA), sodium iodide scintillators 15 200...

view Abstract Citations (595) References (94) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Accretion powered X-ray pulsars. White, N. E. ; Swank, J. H. Holt, S. The current theoretical understanding of the properties pulsars is assessed through a comparison with unified descriptions 14 such systems, extending over six orders magnitude in luminosity, whose phase averaged spectra only notable trend less abrupt high energy cutoff lower luminosity systems....

We report the detection with Proportional Counter Array (PCA) on board Rossi X-Ray Timing Explorer (RXTE) of millisecond variability in X-ray emission from low-mass binary 4U 1728-34. Pulsations at 363 Hz amplitudes (rms) 2.5%-10% are present six eight bursts analyzed to date. The strongest were seen two successive recorded 1996 February 16 when quiescent count rate was near highest by PCA. pulsations during these show frequency changes 1.5 first few seconds but become effectively coherent...

view Abstract Citations (222) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dead-Time Modifications to Fast Fourier Transform Power Spectra Zhang, W. ; Jahoda, K. Swank, J. H. Morgan, E. Giles, A. B. Time series analysis in X-ray astronomy is complicated by the effects of detector dead time which can cause significant departures power spectra from those expected simple Poisson statistics. In this paper we study both paralyzable and...

We report the discovery, with NASA's Rossi X-Ray Timing Explorer (RXTE), of first submillisecond oscillations found in a celestial X-ray source. The quasi-periodic (QPOs) come from Sco X-1 and have frequency ~1100 Hz amplitudes 0.6%-1.2% (rms) are relatively coherent, Q up to ~102. QPOs increases accretion rate, rising 1050 1130 when source moves top bottom along normal branch color-color diagram, shows strong, approximately linear correlation well-known 6-20 normal/flaring-branch QPOs. also...

We report the discovery of a new X-ray pulsar, XTE J1810-197, that was serendipitously discovered on 2003 July 15 by Rossi X- Ray Timing Explorer (RXTE) while observing soft gamma repeater SGR 1806-20. The pulsar has 5.54 s spin period, spectrum (with photon index ≈4), and is detectable in earlier RXTE observations back to January but not before. These show transient outburst began between 2002 November 17 23 source's persistent flux been declining since then. exhibits high spin-down rate ≈...

view Abstract Citations (224) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The periodic absorption events from 4U 1915-05. White, N. E. ; Swank, J. H. An analysis of X-ray observations shows that the steady flux 1915-05 undergoes dips with a period 50 minutes. This most probably represents underlying orbital system, and variations in depth duration these suggest they are caused by bulge on edge accretion disk at point where gas stream...

The HEAO 2 or Einstein solid-state spectrometer (SSS; 0.5-4.5 keV) and monitor proportional counter (MPC; 1.2-20.0 carried out an extensive survey of 49 low-mass X-ray binaries (LMXBs). Simultaneous SSS plus MPC spectra, selected on the basis their intensity, were fitted with a set simple complex spectral models. For all sources, including Eddington-limited bulge bursters, dippers, soft spectrum black hole candidates, few transients in decline, spectra could be acceptably combinations...

We report the results from our timing analysis of 15 Rossi X-Ray Timing Explorer observations Cygnus X-1 throughout its 1996 spectral transitions. The entire period can be divided into three distinct phases: (1) transition hard state to soft state, (2) and (3) back state. observed X-ray properties (both temporal spectral) in Phases 1 3 are remarkably similar, suggesting that same physical processes likely involved triggering such power density spectrum (PDS) during characterized by a...

We report the discovery by Rossi X-Ray Timing Explorer Proportional Counter Array of a second transient accreting millisecond pulsar, XTE J1751-305, during regular monitoring observations Galactic bulge region. The pulsar has spin frequency 435 Hz, making it one fastest pulsars. pulsations contain signature orbital Doppler modulation, which implies an period 42 minutes, shortest any known radio or X-ray pulsar. mass function, fX = (1.278 ± 0.003) × 10-6 M☉, yields minimum for companion...

The HEAO A2 experiment data was systematically searched for unresolved galactic disc emission. Although there were suggestions of non-uniformities in the emission, consistent with a half-thickness 241 + 22 pc and surface emissivity (2-10 keV) at radius R(kpc) 2.2 10 to minus 7th power exp(-R/3.5) erg/sq cm (-2)power/s (R 7.8 kpc). giving luminosity approximately 4.4 37th erg S (-1) power. If model is extrapolated radii less than kpc, emission 1.4 38th i.e., few percent galaxy resolved...

We discuss the results of long-term hard X-ray monitoring Galactic black hole candidates 1E 1740.7-2942, GRS 1758-258, Cyg X-1, GX 339-4, and X-3 with Rossi X-Ray Timing Explorer. The objects divide into two classes. In first class, exemplified by luminosity spectral hardness evolve simultaneously. second relation is more complicated: softest spectra occur while count rate dropping. Most models accretion, tailored to do not predict sort behavior. One interpretation a simple model...

view Abstract Citations (160) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectral evolution of a long X-ray burst. Swank, J. H. ; Becker, R. Boldt, E. A. Holt, S. Pravdo, Serlemitsos, P. Results are reported for spectroscopic observations an burstlike event that had duration 100 sec and peak count range 1.5 times the Crab Nebula. The best position determined is 356.4 deg galactic longitude, 2.3 latitude. It shown spectrum source changed...

view Abstract Citations (229) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-radiation from clusters of galaxies: spectral evidence for a hot evolved gas. Serlemitsos, P. J. ; Smith, B. W. Boldt, E. A. Holt, S. Swank, H. OSO-8 observations the X-ray flux in range between 2 and 60 keV Virgo, Perseus, Coma provide strong thermal origin radiation, including iron-line emission. The data are adequately described by emission an isothermal plasma...

On 2004 December 27, a highly-energetic giant flare was recorded from the magnetar candidate SGR 1806-20. In months preceding this flare, persistent X-ray emission object began to undergo significant changes. Here, we report on evolution of key spectral and temporal parameters prior following flare. Using Rossi Timing Explorer, track pulse frequency 1806-20 find that spin-down rate varied erratically in before after Contrary 1900+14, no evidence for discrete jump spin at time 27th (|dnu/nu|...

view Abstract Citations (151) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray spectra of Orion OB supergiants. Cassinelli, J. P. ; Swank, H. The are at a higher energy resolution than earlier observations supergiants, and this allows stronger constraints to be placed on the location emission source in outer atmosphere. all three stars found consistent with thermal sources which only slightly attenuated by stellar wind opacity have...

view Abstract Citations (180) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Two-component X-ray emission from RS CVn binaries. Swank, J. H. ; White, N. E. Holt, S. Becker, R. A summary is presented of results the Solid State Spectrometer on Einstein Observatory for seven The spectra all require two components, evidenced by line characteristics plasma at 4-million to 8-million K and bremsstrahlung characteristic 20-million 100-million K. data...

We report the results from a long-term monitoring data set obtained with Rossi X-Ray Timing Explorer (RXTE) bright globular cluster binary source 4U 1820-30. During this monitoring, flux varied 2.9×10−9 to 8.5×10−9 ergs cm-2 s-1 in 2-10 keV band, which correspond to, respectively, count rates of 1600 and 4500 counts nominal 2-60 RXTE proportional counter array band. Its energy spectral state was observed encompass both banana branches island state. Kilohertz quasi-periodic oscillations (kHz...

We report a study of the temporal and spectral characteristics rising portions X-ray bursts from 4U 1728-34 observed with Rossi X-Ray Timing Explorer (RXTE). find that when oscillations are present during burst rise, their amplitudes systematically decrease as flux increases, reaching undetectable levels near peaks before eventually increasing again later in burst. Oscillation high 43% ± 12% measured within first 0.2 s onset have pulse shapes consistent sinusoids. Spectral analysis indicates...

We solve the Rossi X-Ray Timing Explorer X-ray light curve of extremely luminous and massive star η Carinae with a colliding-wind emission model to refine ground-based orbital elements. The sharp decline minimum at end 1997 fixes date last periastron passage 1997.95 ± 0.05, not 1998.13 as derived from radial velocities. This helps resolve discrepancy between velocities spatially resolved velocity measures obtained by Space Telescope Imaging Spectograph (STIS). data are consistent mass...

Recent studies by Damineli and coworkers suggest that the supermassive star η Carinae may have a massive stellar companion, although dense ejecta surrounding make this claim hard to test using conventional methods. Settling question is critical for determining current evolutionary state future evolution of star. We address problem an unconventional method: If binary, X-ray emission should be produced in shock waves generated wind-wind collisions region between its companion. Detailed...

The Rossi X-Ray Timing Explorer observed the soft X-ray transient Aquila X-1 during its outburst in 1997 February and March. We report discovery of quasi-periodic oscillations (QPOs) persistent flux with frequencies range 740-830 Hz, a Q-value over 100, fractional rms amplitude 6.8%±0.6%, nearly coherent (NCOs) type I burst frequency 549 Hz. QPOs is correlated mass accretion rate on timescale hours, but not days. This most likely manifestation single source kilohertz QPO puzzle among many...

We report evidence of cyclotron resonance features from the Soft Gamma Repeater SGR 1806-20 in outburst, detected with Rossi X-Ray Timing Explorer spectrum a long, complex precursor that preceded strong burst. The consist narrow 5.0 keV absorption line modulation near its second and third harmonics (at 11.2 17.5 keV, respectively). are transient harder part precursor. feature is strong, an equivalent width ~500 eV less than 0.4 keV. Interpreting as electron-cyclotron lines context accretion...