A5047396683- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Adaptive optics and wavefront sensing
- Advanced X-ray Imaging Techniques
- Scientific Measurement and Uncertainty Evaluation
- Calibration and Measurement Techniques
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Mechanics and Biomechanics Studies
- Atomic and Molecular Physics
- History and Developments in Astronomy
- Medical Imaging Techniques and Applications
The University of Texas at San Antonio
2016-2025
Harvard University
2000-2013
Seattle University
2011
United States Naval Observatory
2011
Middle East Technical University
2011
European Space Astronomy Centre
2011
Villanova University
2011
Center for Astrophysics Harvard & Smithsonian
1997-2007
Smithsonian Astrophysical Observatory
1998-2007
Harvard College Observatory
2003
We have analyzed Chandra High Resolution Camera observations of the starburst galaxy M82, concentrating on most luminous x-ray source. find a position for source $\rm R.A. = 09^h 55^m 50^s.2, decl. +69^{\circ} 40\arcmin 46\arcsec.7$ (J2000) with $1σ$ radial error $0.7\arcsec$. The accurate shows that is not at dynamical centre M82 nor coincident any suggested radio AGN candidate. highly variable between observations, which suggests compact object and supernova or remnant. There no...
The first extragalactic X-ray binary, LMC X-1, was discovered in 1969. In the 1980s, its compact primary established as fourth dynamical black hole candidate. Recently, we published accurate values for mass of and orbital inclination angle binary system. Building on these results, have analyzed 53 spectra obtained by RXTE and, using a selected sample 18 spectra, determined dimensionless spin parameter to be a* = 0.92+0.05−0.07. This result takes into account all sources observational...
We report extensive optical photometry and spectroscopy of the Type Ia supernova 1989B. Maximum light in B occurred approximately seven days after discovery on JD 2447565.3+/-1.0 (1989 February 7.8+/-1.0) at a magnitude 12.34+/-0.05. The UBV curves this were very similar to those other well observed events such as SN 1981B 1980N. From comparison UBVRIJHK photometry, we derive an extinction for 1989B E(B-V)=0.37+/-0.03 mags relative unobscured 198ON. properties dust responsible reddening...
We present UBVRIJHK photometry and optical spectroscopy of the so-called peculiar Type Ia supernova 1999by in NGC 2841. The observations began 1 week before visual maximum light, which is well defined by daily observations. light curves spectra are similar to those prototypical subluminous event SN 1991bg. find that B occurred on 1999 May 10.3 UT (JD 2,451,308.8 ± 0.3) with = 13.66 0.02 a color Bmax - Vmax 0.51 0.03. late-time implies minimal dust extinction from host galaxy. Our photometry,...
The Chandra Multi-wavelength Project (ChaMP) is a wide-area (~14 deg^2) survey of serendipitous X-ray sources, aiming to establish fair statistical samples covering wide range characteristics (such as absorbed AGNs, high z clusters galaxies) at flux levels (fX ~ 10^-15 - 10^-14 erg sec-1 cm-2) intermediate between the Deep surveys and previous missions. We present first ChaMP catalog, which consists 991 near on-axis, bright sources obtained from initial sample 62 observations. data have been...
view Abstract Citations (125) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Doppler Imaging of the Dwarf Nova U Geminorum Marsh, Thomas R. ; Horne, Keith Schlegel, Eric M. Honeycutt, Kent Kaitchuck, Ronald H. tomography is applied to time-resolved spectra dwarf nova Geminorum, and it found that emission from bright-spot region has neither velocity gas stream nor disk along but lies roughly midway between. It shown earlier observations Gem...
The historical supernova (SN) S Andromedae (S And or SN1885A) in the Andromeda Galaxy (M31) was discovered August 1885 and since then has been studied extensively multi-wavelength observations. Although remnant of could be detected optical images, so far no X-ray source reported at position And. In this work we report first detection emission from SN1885A with a significance σ = 3.43 using Chandra High-Resolution Camera (HRC) data taken imaging (I) mode. A total 45 HRC-I observations were...
Abstract We present an analysis of two epochs ACIS observations the SA(s)c spiral galaxy NGC 3938 with Chandra X-ray Observatory. The total exposure time was 95 ks, a limiting unabsorbed luminosity ≈10 38 erg s −1 assuming distance 22 Mpc. A 47 discrete merged sources from both were detected at ≈3 σ level or greater D25 radius. demonstrate that nucleus not detected. connect to counterparts in other wavebands degree possible. Based on epochs, we identify three variable and additional may have...
We present a new technique called "quantile analysis" to classify spectral properties of X-ray sources with limited statistics. The quantile analysis is superior the conventional approaches such as hardness ratio or color study relatively faint investigate certain phase state source in detail, where poor statistics does not allow fitting using model. Instead working predetermined energy bands, we determine values that divide detected photons into fractions total counts median (50%), tercile...
view Abstract Citations (126) References (60) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS SN 1978K: an Extraordinary Supernova in the Nearby Galaxy NGC 1313 Ryder, Stuart ; Staveley-Smith, Lister Dopita, Michael Petre, Robert Colbert, Edward Malin, David Schlegel, Eric We have identified extremely luminous radio and X-ray source with optically variable emission-line object outskirts of nearby barred spiral galaxy 1313. Archival data show that (officially...
We report the Chandra ACIS-S detection of a bright soft X-ray transient in Mira AB interacting symbiotic-like binary. have resolved system for first time X-rays. Using and Hubble Space Telescope images, we determine that unprecedented outburst is likely associated with cool asymptotic giant branch (AGB) star, A, prototype class variables. X-rays never before been detected from an AGB recent activity signals undergoing dramatic changes. The total luminosity several times higher than estimated...
We describe the X-ray analysis procedure of on-going Chandra Multiwavelength Plane (ChaMPlane) survey and report initial results from 15 selected anti-Galactic center observations (90 deg < l 270 deg). procedures for ChaMPlane using custom-developed tools appropriate Galactic sources but also general use: optimum photometry in crowded fields advanced techniques overlapping sources, rigorous astrometry 95% error circles combining images or matching to optical/IR images, application...
view Abstract Citations (94) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An X-Ray and Optical Study of the Supernova Remnant W44 Rho, Jeonghee ; Petre, R. Schlegel, Eric M. Hester, J. Jeff We report results a 8000 s observation supernova remnant using ROSAT Position Sensitive Proportional Counter (PSPC). The image shows same centrally peaked morphology observed by Einstein IPC contrasts with shell-like radio morphology. eastern limb lack...
We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, 2005cf) obtained with the UV prism Advanced Camera for Surveys on Hubble Space Telescope. This data set provides unique spectral time series down to 2000 Å. Significant diversity is seen in near-maximum-light spectra (∼2000–3500 Å) this small sample. The corresponding photometric data, together archival from Swift Ultraviolet/Optical Telescope observations, provide further evidence...
We present the first results of ChaMP X-ray source properties obtained from initial sample 62 observations. The data have been uniformly reduced and analyzed with techniques specifically developed for then validated by visual examination. Utilizing only near on-axis, bright sources (to avoid problems caused incompleteness Eddington bias), we derive Log(N)-Log(S) relation in soft (0.5-2 keV) hard (2-8 energy bands. are consistent previous ROSAT, ASCA Chandra deep surveys. In particular, our...
We report on a 1 day ASCA observation and ROSAT HRI observations of the eclipsing dwarf nova HT Cas. The presence X-ray eclipse, originally detected in PSPC observation, is confirmed at much higher significance level. quality light curve high enough to allow detailed investigation eclipse depth, width, shape. found be deep, compatible with being total. width comparable that white dwarf, as derived from optical curves, fact may narrower. transition also short, which puts limit 1.15 times...
view Abstract Citations (96) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Atlas of Doppler Emission-Line Tomography Cataclysmic Variable Stars Kaitchuck, Ronald H. ; Schlegel, Eric M. Honeycutt, R. Kent Horne, Keith Marsh, T. White, J. C., II Mansperger, Cathy S. emission-line tomography is a technique similar to medical tomography. In this atlas the profiles cataclysmic variable stars, seen at different orbital phases, are transformed...
view Abstract Citations (107) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for a Bipolar Wind in the Cataclysmic Variable PG 1012-029 Honeycutt, R. K. ; Schlegel, E. M. Kaitchuck, H. A study of 1012-029, nova-like variable which undergoes deep eclipses by secondary star, is reported. Whole-orbit time resolved spectrophotometry has been used to size, shape and kinematics accretion disk. Analysis line continuum eclipse light curves...
Time-resolved spectroscopy during primary eclipse was utilized in order to search for emission lines from accretion disks surrounding the component short-period Algol systems. The authors present results of observations 46 systems surveyed 80 eclipses. When combined with an earlier survey this makes a total 52 and 104 A distinction is made between long-period those In former case gas stream secondary star moves around trailing hemisphere forms permanent disk. However, latter strikes star....
We present results from a Chandra X-Ray Observatory study of the field X-ray source populations in four different observations: two high-redshift (z ~ 0.5) clusters galaxies 3C 295 and RX J003033.2+261819; noncluster fields with similar exposure time. Surprisingly, 0.5-2 keV surface densities (~900-1200 sources deg-2 at flux limit 1.5 × 10-15 ergs cm-2 s-1) measured an ~8' 8' area surrounding each cluster exceed by factor ~2 value expected on basis ROSAT log N- S, significance σ each, or...
We present observations of the young, oxygen-rich supernova remnant 1E 0102.2-7219 taken by Chandra X-Ray Observatory during its orbital activation and checkout phase. The boundary blast-wave shock is clearly seen for first time, allowing diameter mean velocity to be determined accurately. prominent X-ray bright ring material may result reverse encountering ejecta; radial variation O VII versus VIII emission indicates an ionizing propagating inward, possibly through a strong density gradient...
We present photometry from ~380 to ~520 days past maximum and spectroscopy at ~400 for the type Ib supernova 1984L. The late-time light curve shows an exponential decline with e-folding time of ~116 days, within errors, same as ^56^Co decay, which powers SN 1987A. If observed flux arises radioactive decay ^56^Co, luminosity implies initial ^56^Ni mass ~0.1 M_sun_. spectrum is dominated by [O I] 6300-6363 emission. required oxygen (~1 M_sun_), ratios magnesium carbon all seem consistent...