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Chandra and VLA observations of the symbiotic star R Aqr in 2004 reveal significant changes over the three to four year interval between these observations and previous observations taken with the VLA in 1999 and with Chandra in 2000. This paper reports on the evolution of the outer thermal X-ray lobe-jets and radio jets. The emission from the outer X-ray lobe-jets lies farther away from the central binary than the outer radio jets, and comes from material interpreted as being shock heated to ~10^6 K, a likely result of collision between high speed material ejected from the central binary and regions of enhanced gas density. Between 2000 and 2004, the Northeast (NE) outer X-ray lobe-jet moved out away from the central binary, with an apparent projected motion of ~580 km s^-1. The Southwest (SW) outer X-ray lobe-jet almost disappeared between 2000 and 2004, presumably due to adiabatic expansion and cooling. The NE radio bright spot also moved away from the central binary between 2000 and 2004, but with a smaller apparent velocity than of the NE X-ray bright spot. The SW outer lobe-jet was not detected in the radio in either 1999 or 2004. The density and mass of the X-ray emitting material is estimated. Cooling times, shock speeds, pressure and confinement are discussed., Comment: 23 pages, 8 figures

Two Chandra observations of the R Aqr symbiotic binary system taken 3.3 years apart show dramatic changes in the X-ray morphology and spectral characteristics in the inner 500 AU of this system. The morphology of the soft X-ray emission has evolved from a nearly circular region centered on the binary system to an hourglass shape that indicates the formation of a new southwest jet. Synchrotron radiation from the new jet in contemporaneous VLA radio spectra implies the physical conditions in the early stages of jet development are different from those in the more extended outer thermal jets known to exist for decades in this system. The central binary source has two X-ray spectral components in each of the two epochs, a soft component and a highly absorbed hard component characterized by T ~ 10^8 K if fit with a thermal plasma model. The spectrum hardened considerably between 2000.7 and 2004.0, primarily due to increased flux above 5 keV, suggesting a change in the accretion activity of the white dwarf on a timescale of a few years or less. Point-source Fe K emission is detected at the position of the central binary system in both observations. While the earlier observation shows evidence of only a single emission peak near Fe K alpha at 6.4 keV, the later observation shows a more complex emission structure between 6 and 7 keV. Finally, we have discovered a modulation in the hard X-ray flux with a period of 1734 s at a 95% confidence level in the 2004 observation only. The modulation potentially arises from standing shocks in an accretion column and we have explored the possibility that the white dwarf in R Aqr is analogous to the magnetic white dwarfs in Intermediate Polar., Comment: 31 pages, 14 figures, 1 table To be published in ApJ, expected April 10 issue. AAS LaTex style

The amount of mass loss in symbiotic systems is investigated, specifically mass loss via the formation of jets in R Aquarii (R Aqr). The jets in R Aqr have been observed in the X-ray by Chandra over a four year time period. The jet changes on times scales of a year and new outflows have been observed. Understanding the amount of mass and the frequency of ejection further constrain the ability of the white dwarf in the system to accrete enough mass to become a Type 1a supernova progenitor. The details of multi-wavelength studies, such as speed, density and spatial extent of the jets will be discussed in order to understand the mass balance in the binary system. We examine other symbiotic systems to determine trends in mass loss in this class of objects., Comment: To be published in the proceedings of "The Multicoloured Landscape of Compact Objects and their Explosive Origins"

Collimated outflows from accreting white dwarfs have an important role to play in the study of astrophysical jets. Observationally, collimated outflows are associated with systems in which material is accreted though a disk. Theoretically, accretion disks provide the foundation for many jet models. Perhaps the best-understood of all accretion disks are those in cataclysmic variable stars (CVs). Since the disks in other accreting white-dwarf (WD) binaries are probably similar to CV disks (at least to the extent that one does not expect complications such as, for example, advection-dominated flows), with WD accretors one has the advantage of a relatively good grasp of the region from which the outflows are likely to originate. We briefly compare the properties of the three main classes of WD accretors, two of which have members that produce jets, and review the cases of three specific jet-producing WD systems., Comment: 2 pages, 1 figure, to appear in the proceedings of IAU Colloquium 194, Compact Binaries in the Galaxy and Beyond

We report Chandra ACIS-S3 x-ray imaging and spectroscopy of the R Aquarii binary system that show a spatially resolved two-sided jet and an unresolved central source. This is the first published report of such an x-ray jet seen in an evolved stellar system comprised of ~2-3 solar masses. At E < 1 keV, the x-ray jet extends both to the northeast and southwest relative to the central binary system. At 1 < E < 7.1 keV, R Aqr is a point-like source centered on the star system. While both 3.5-cm radio continuum emission and x-ray emission appear coincident in projection and have maximum intensities at ~7.5" northeast of the central binary system, the next strongest x-ray component is located \~30" southwest of the central binary system and has no radio continuum counterpart. The x-ray jets are likely shock heated in the recent past, and are not in thermal equilibrium. The strongest southwest x-ray jet component may have been shocked recently since there is no relic radio emission as expected from an older shock. At the position of the central binary, we detect x-ray emission below 1.6 keV consistent with blackbody emission at T ~2 x 10^6 K. At the central star there is also a prominent 6.4 keV feature, a possible fluorescence or collisionally excited Fe K-alpha line from an accretion disk or from the wind of the giant star. For this excitation to occur, there must be an unseen hard source of x-rays or particles in the immediate vicinity of the hot star. Such a source would be hidden from view by the surrounding edge-on accretion disk., Comment: PS, 20 pages, including 3 figures PNG, JPG - accepted for publication in ApJ Letters. Subject headings: stars: individual (R Aquarii) -- binaries: symbiotic -- circumstellar matter -- stars: white dwarfs -- stars: winds, outflows -- radio continuum: stars -- x-rays: general

We present results from a Chandra X-ray Observatory study of the field X-ray source populations in 4 different observations: two high-redshift (z~0.5) clusters of galaxies 3C295 and RXJ003033.2+261819; and two non-cluster fields with similar exposure time. Surprisingly, the 0.5-2 keV source surface densities (~900-1200 sources deg**-2 at a flux limit of 1.5x10**-15 erg cm**-2s**-1) measured in an ~8'x8' area surrounding each cluster exceed by a factor of ~2 the value expected on the basis of the ROSAT and Chandra logN-logS, with a significance of ~2 sigma each, or ~3.5 sigma when the 2 fields are combined (i.e. a probability to be a statistical fluctuation of <1% and <0.04%, respectively). The same analysis performed on the non-cluster fields and on the outer chips of the cluster fields does NOT show evidence of such an excess. In both cluster fields, the summed 0.5-10 keV spectrum of the detected objects is well fitted by a power-law with Gamma~1.7 similar to AGNs and shows no sign of intrinsic absorption. The few (~10 out of 35) optical identifications available to date confirm that most of them are, as expected, AGNs but the number of redshifts available is too small to allow conclusions on their nature. We discuss possible interpretations of the overdensity in terms of: a statistical variation of Cosmic Background sources; a concentration of AGNs and/or powerful starburst galaxies associated with the clusters; and g ravitational lensing of background QSO's by the galaxy clusters. All explanations are however difficult to reconcile with the large number of excess sources detected. Deeper X-ray observations and more redshifts measurements are clearly required to settle the issue., Comment: 22 LateX pages (including Tables and Figures), uses psfig.sty and emulateapj.sty. Accepted for publication in Astrophysical Journal

We use Chandra data to map the gas temperature in the central region of the merging cluster A2142. The cluster is markedly nonisothermal; it appears that the central cooling flow has been disturbed but not destroyed by a merger. The X-ray image exhibits two sharp, bow-shaped, shock-like surface brightness edges or gas density discontinuities. However, temperature and pressure profiles across these edges indicate that these are not shock fronts. The pressure is reasonably continuous across these edges, while the entropy jumps in the opposite sense to that in a shock (i.e. the denser side of the edge has lower temperature, and hence lower entropy). Most plausibly, these edges delineate the dense subcluster cores that have survived a merger and ram pressure stripping by the surrounding shock-heated gas., Comment: Latex, 9 pages, 5 figures (including color), uses emulateapj.sty. Submitted to ApJ

The amount of mass loss in symbiotic systems is investigated, specifically mass loss via the formation of jets in R Aquarii (R Aqr). The jets in R Aqr have been observed in the X-ray by Chandra over a four year time period. The jet changes on times scales of a year and new outflows have been observed. Understanding the amount of mass and the frequency of ejection further constrain the ability of the white dwarf in the system to accrete enough mass to become a Type la supernova progenitor. The details of multi-wavelength studies, such as speed, density and spatial extent of the jets will be discussed in order to understand the mass balance in the binary system. We examine other symbiotic systems to determine trends in mass loss in this class of objects.

We report on multiple Chandra observations spanning a period of 5 years as well as a more recent XMM observation of the nearby symbiotic binary R Aqr. Spectral analysis of these four observations reveals considerable variability in hardness ratios and in the strength and ionization levels of emission lines which provides insight into white dwarf accretion processes as well as continuum and line formation mechanisms. Chandra imaging of the central source also shows the formation and evolution of a new south west jet. This growing body of high-resolution X-ray data of R Aqr provides a unique glimpse into white dwarf wind-accretion processes and jet formation.

The symbiotic star R Aquarii has been known to emit collimated outflow in the form of jets for many years. We report on five years of observations in x-rays and radio using Chandra, VLA and XMM-Newton. We discuss the evolution of the outer thermal jets, including new observations performed in June and October 2005. We see motion of the NE x-ray jet at a projected velocity of about 600 km (sup -1). The SW x-ray jet has almost disappeared between 2000.7 and 2004.0. An XMM grating spectrum of the NE jet confirms the existence of O VII He-like lines, and offers the possibility of doing plasma density diagnostics. We comment on on the physics of cooling in the SW jet and implications for the density of the x-ray emitting gas, the heating mechanism, and mass and kinetic energy in the jets and its implications for the system as a whole. This work was supported by NASA and NSF.

The Chandra X-ray Observatory was launched in July 1999, and is returning exquisite sub-arcsecond x-ray images of star groups, supernova remnants, galaxies, quasars, and clusters of galaxies. In addition to being the premier X-ray observatory in terms of angular and spectral resolution, Chandra is the best calibrated X-ray facility ever flown. We discuss here the calibration of the effective area of the High Resolution Mirror Assembly. Because we do not know the absolute X-ray flux density of any celestial source, this must be based primarily on ground measurements and on modeling. In particular, we must remove the calibrated modeled responses of the detectors and gratings to obtain the mirror area. For celestial sources which may be assumed to have smoothly varying spectra, such as the Crab Nebula, we may verify the continuity of the area calibration as a function of energy. This is of significance in energy regions such as the Ir M-edges, or near the critical grazing angle cutoff of the various mirror shells.

The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is, however, a function of energy, off-axis angle of the source, and operating mode of the facility. No single measurement would yield the entire result. Also, any calibration made prior to launch will be affected by changes in conditions after launch, such as the change from one g to zero g. The reflectivity of the mirror and perhaps even the detectors can change as well, for example by addition or removal of small amounts of material deposited on their surfaces. In this paper, we give a broad view of the issues in performing such a calibration, and discuss how they are being addressed in prelaunch preparation of AXAF. As our title indicates, we concentrate here on the total throughput of the observatory. This can be thought of as the integral of the point response function, i.e. the encircled energy, out ot the largest practical solid angle for an observation. Since there is no standard x-ray source in the sky whose flux is known to the -1% accuracy we are trying to achieve, we must do this calibration on the ground. we also must provide a means for monitoring any possible changes in this calibration from pre-launch until on-orbit operation can transfer the calibration to a celestial x-ray source whose emission is stable. In this paper, we analyze the elements of the absolute throughput calibration, which we call Effective Area. We review the requirements for calibrations of components or subsystems of the AXAF facility, including mirror, detectors, and gratings. We show how it is necessary to calibrate this ground-based detection system at standard man-made x-ray sources, such as electron storage rings. We present the status of all these calibrations, with indications of the measurements remaining to be done, even though the measurements on the AXAF flight optics and detectors will have been completed by the time this paper is presented. We evaluate progress toward the goal of making 1% measurements of the absolute x-ray flux from astrophysical sources, so that comparisons can be made with their emission at other wavelengths, in support of observations such as the Sunyaev-Zeldovitch effect, which can give absolute distance measurements independent of the traditional distance measuring techniques in astronomy.

The following summarizes requirements on the High Resolution Mirror Assembly (HRMA) and HRMA/SI calibration. The lists of calibration measurements assume that the HRMA meets the CTT requirement that the XRCF test environment shall have not more than a 10 percent effect on the encircled energy in 1 arcsec and that it can be calibrated to 1 percent. This implies that the offloading scheme has been implemented in the HRMA. It should be remembered that there are additional calibrations needed for: aspect system; tracking; gyros; other parts of the PCAS; spacecraft timing and checks on timing accuracy for all SIs after integration in the spacecraft; ficucial lights and periscope; alignments; optical metrology data: lengths and diameters with errors on mirror elements and optical interferometer data on surface figure; and throughput and imaging stability test: an end-to-end test that can be used after the XRCF to verify that the x-ray throughput and imaging quality have not been degraded. The tables presented give a summary of the integration times for HRMA and HRMA/SI calibration.

The study measures the X-ray reflectivity of the AXAF VETA-I optic and compares it with theoretical predictions. Measurements made at energies of 0.28, 0.9, 1.5, 2.1, and 2.3 keV are compared with predictions based on ray trace calculations. Results on the variation of the reflectivity with energy as well as the absolute value of the reflectivity are presented. A synchrotron reflectivity measurement with a high-energy resolution over the range 0.26 to 1.8 keV on a flat Zerodur sample is also reported. Evidence is found for contamination of the flat by a thin layer of carbon on the surface, and the possibility of alteration of the surface composition of the VETA-I mirror, perhaps by the polishing technique. The overall agreement between the measured and calculated effective area of VETA-I is between 2.6 and 10 percent. Measurements at individual energies deviate from the best-fitting calculation to 0.3 to 0.8 percent, averaging 0.6 percent at energies below the high energy cutoff of the mirror reflectivity, and are as high as 20.7 percent at the cutoff.

We are developing a system to calibrate reflectances of witness coupons to the AXAF flight mirrors at the National Synchrotron Light Source over the 0.05-12 keV energy range. These witness coupons will be coated in the same process as the AXAF mirror elements. One of the key issues is the accurate determination of mirror efficiencies across the absorption edges of the mirror coating elements. We present a series of reflectance measurements with 2 eV resolution of a nickel-coated flat mirror in the region of the Ni L-II (870 eV) and L-III (853 eV) absorption edges. Scans of reflectance versus grazing angle at fixed energies in this region show distinct interference fringes at grazing angles larger than the critical angle which are extinguished as the photon energy is increased beyond the low point of the L-III edge, indicating total absorption of the evanescent wave within the Ni film. At 51 arc minutes grazing angle, measured reflectance decreases smoothly by 35 percent and then recovers in an 8 eV band at the L-III edge. We have also measured reflectances in the M absorption edge region for gold, platinum, and iridium coated mirrors. We derive optical parameters n and k specific to the film for comparison to the existing data tables.

The VETA-I mirror was calibrated with the use of a collimated soft X-ray source produced by electron bombardment of various anode materials. The FWHM, effective area and encircled energy were measured with the use of proportional counters that were scanned with a set of circular apertures. The pulsers from the proportional counters were sent through a multichannel analyzer that produced a pulse height spectrum. In order to characterize the properties of the mirror at different discrete photon energies one desires to extract from the pulse height distribution only those photons that originated from the characteristic line emission of the X-ray target source. We have developed a code that fits a modeled spectrum to the observed X-ray data, extracts the counts that originated from the line emission, and estimates the error in these counts. The function that is fitted to the X-ray spectra includes a Prescott function for the resolution of the detector a second Prescott function for a pileup peak and a X-ray continuum function. The continuum component is determined by calculating the absorption of the target Bremsstrahlung through various filters, correcting for the reflectivity of the mirror and convolving with the detector response.

Measurements of the VETA encircled energies have been performed at 5 energies within 16 radii ranging from 0.05 to 200 arcseconds. We report here on the analysis of the accuracy of those measurements. A common 'error tree' structure applies, and we present representative numbers for the larger terms. At 0.277, 1.5, and 2.07 keV, and for radii of 3 arcsec and larger, our measurements have estimated 1 sigma errors of 0.6 to 1.5 percent. Effects of measurement statistics and of the VETA test mount limit the accuracy at smaller angles, and modulation by the counter window support structure together with the imperfect position repeatability limit the accuracy for the 0.93 and 2.3 keV energies. We expect to mitigate these limitations when calibrating the complete AXAF flight mirror assembly.

This interim report presents some definitive results from our analysis of the VETA-I x-ray testing data. It also provides a description of the hardware and software used in the conduct of the VETA-I x-ray test program performed at the MSFC x-ray Calibration Facility (XRCF). These test results also serve to supply data and information to include in the TRW final report required by DPD 692, DR XC04. To provide an authoritative compendium of results, we have taken nine papers as published in the SPIE Symposium, 'Grazing Incidence X-ray/EUV Optics for Astronomy and Projection Lithography' and have reproduced them as the content of this report.

Advanced X-ray Astrophysics Facility (AXAF) X-ray optics testing is conducted by VETA-I, which consists of six nested Wolter type I grazing-incidence mirrors; VETA's X-ray Detection System (VXDS) in turn measures the imaging properties of VETA-I, yielding FWHM and encircled energy of the X-ray image obtained, as well as its effective area. VXDS contains a high resolution microchannel plate imaging X-ray detector and a pinhole scanning system in front of proportional-counter detectors. VETA-I's X-ray optics departs from the AXAF flight configuration in that it uses a temporary holding fixture; its mirror elements are not cut to final length, and are not coated with the metal film used to maximize high-energy reflection.

The 1-percent calibration accuracy goal of the Advanced X-ray Astrophysics Facility is being approached by way of an experiment at the National Synchrotron Light Source that will demonstrate the accuracy achievable in reflectance measurements conducted on coated flat mirrors in the 50 eV-12 keV energy range. The coatings will be of commercially produced Au, Ni, and Ir, deposited either by sputtering or by e-beam deposition. Optical constants will be estimated via the reflectance vs. angle-of-incidence method.

Five research projects concerning the Romanization of the Hebrew alphabet and its effect on the progress of adult English speakers learning Hebrew as a second language are reviewed. The hypotheses, subjects, procedures, results, conclusions, and validity of each study are summarized. The studies dealt with the Hebrew alphabet, spelling, plural forms, noun forms, and a measure of language ability. Introducing the learner to Hebrew by means of the Latin alphabet should eliminate the problems involved in learning a different alphabet and set of recognition techniques. Among the difficulties inherent in learning the Hebrew alphabet are that the language is written from right to left and that there are several pairs of identical letters that complicate spelling. A morpheme per utterance measure was developed and evaluated, and appears to be as valid for Hebrew as the mean length of utterance measure is for English. (RW)