The Infrared Detection of the Pulsar Wind Nebula in the Galactic Supernova Remnant 3C 58 (2008)
Slane, P., Helfand, D. J., Reynolds, S. P., Gaensler, B. M., Lemiere, A., Wang, Z.
We present infrared observations of 3C 58 with the Spitzer Space Telescope and the Canada-France-Hawaii Telescope. Using the IRAC camera, we have imaged the entire source resulting in clear...
Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75 (2007)
Morton, T. D., Slane, P., Borkowski, K. J., Reynolds, S. P., Helfand, D. J., Gaensler, B. M., ...
We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas...
The variable radio-to-X-ray spectrum of the magnetar XTE J1810-197 (2007)
Camilo, F., Ransom, S. M., Penalver, J., Karastergiou, A., Van Kerkwijk, M. H., Durant, M., ...
We have observed the 5.54s anomalous X-ray pulsar XTE J1810-197 at radio, millimeter, and infrared (IR) wavelengths, with the aim of learning about its broad-band spectrum. At the IRAM 30m telescope,...
Helfand, D. J., Gotthelf, E. V., Halpern, J. P., Camilo, F., Semler, D. R., Becker, R. H., ...
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located...
Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey (2007)
De Vries, W. H., Hodge, J. A., Becker, R. H., White, R. L., Helfand, D. J.
We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by co-adding large...
Discovery of a Pulsar Candidate Associated with the TeV Gamma-ray Source HESS J1813-178 (2007)
Gotthelf, E. V., Helfand, D. J.
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located...
VLBA measurement of the transverse velocity of the magnetar XTE J1810-197 (2007)
Helfand, D. J., Chatterjee, S., Brisken, W. F., Camilo, F., Reynolds, J., Van Kerkwijk, M. H., ...
We have obtained observations of the magnetar XTE J1810-197 with the Very Long Baseline Array at two epochs separated by 106 days, at wavelengths of 6 cm and 3.6 cm. Comparison of the positions...
Camilo, F., Cognard, I., Ransom, S. M., Halpern, J. P., Reynolds, J., Zimmerman, N., ...
We report on 9 months of observations of the radio-emitting anomalous X-ray pulsar XTE J1810-197 starting in 2006 May using the Nancay, Parkes, GBT, and VLA telescopes mainly at a frequency of 1.4...
Petric, A. O., Telis, G. A., Paerels, F., Helfand, D. J.
We report on the results of a search for an intergalactic X-ray dust scattering halo in a deep observation of the bright, high-redshift quasar QSO 1508+5714 with the Chandra X-ray Observatory. We do...
A Shell of Thermal X-ray Emission Associated with the Young Crab-like Remnant 3C58 (2006)
Gotthelf, E. V., Helfand, D. J., Newburgh, L.
Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C58 confirms the existence of an embedded thermal X-ray shell surrounding the pulsar PSR J0205+6449. Radially resolved spectra...
Discovery of Radio Emission from Transient Anomalous X-ray Pulsar XTE J1810-197 (2005)
Halpern, J. P., Gotthelf, E. V., Becker, R. H., Helfand, D. J., White, R. L.
We report the first detection of radio emission from any anomalous X-ray pulsar (AXP). Data from the Very Large Array (VLA) MAGPIS survey with angular resolution 6" reveals a point-source of flux...
A New Radio Catalog of Compact HII Regions in the Milky Way II. The 1.4 GHz Data (2005)
Giveon, U., Becker, R. H., Helfand, D. J., White, R. L.
We utilize a new VLA Galactic plane catalog at 1.4 GHz covering the first and second Galactic quadrants (340 deg
X-ray, Radio, and Optical Observations of the Putative Pulsar in the Supernova Remnant CTA 1 (2004)
Halpern, J. P., Gotthelf, E. V., Camilo, F., Helfand, D. J., Ransom, S. M.
A Chandra image of the central X-ray source RX J0007.0+7303 in the supernova remnant CTA 1 reveals a point source, a compact nebula, and a bent jet, all of which are characteristic of energetic,...
X-ray source populations in the Galactic Plane (2004)
Hands, A. D. P., Warwick, R. S., Watson, M. G., Helfand, D. J.
We present the first results from the \xmm Galactic Plane Survey (XGPS). In the first phase of the programme, 22 pointings were used to cover a region of approximately three square degrees between...
Optical Properties of faint FIRST Variable Radio Sources (2004)
De Vries, W. H., Becker, R. H., White, R. L., Helfand, D. J.
A sample of 123 radio sources that exhibit significant variations at 1.4 GHz on a seven year base-line has been created using FIRST VLA B-array data from 1995 and 2002 on a strip at dec=0 near the...
Uncovering High-z Clusters Using Wide-Angle Tailed Radio Sources (2003)
Blanton, E. L., Gregg, M. D., Helfand, D. J., Becker, R. H., White, R. L.
The morphologies of wide-angle tailed (WAT) radio sources (edge-darkened, C-shaped, FR I radio sources) are the result of confinement and distortion of the radio lobes by the dense X-ray-emitting gas...
Constraining the Birth Events of Neutron Stars (2002)
The prescient remark by Baade and Zwicky that supernovae beget neutron stars did little to prepare us for the remarkable variety of observational manifestations such objects display. Indeed, during...
Chandra X-ray Spectroscopy of Kes75, its Young Pulsar, and its Synchrotron Nebula (2001)
Collins, B. F., Gotthelf, E. V., Helfand, D. J.
We have observed the young Galactic supernova remnant Kes 75 with the Chandra X-ray Observatory. This object is one of an increasing number of examples of a shell-type remnant with a central extended...
Halpern, J. P., Gotthelf, E. V., Camilo, F., Collins, B., Helfand, D. J.
With a period of 51.6 ms and spin-down power 2.2x10^{37} erg s^{-1}, PSR J2229+6114 is a compelling identification for the EGRET source 3EG J2227+6122 in which error circle it resides. Striking...
Halpern, J. P., Camilo, F., Gotthelf, E. V., Helfand, D. J., Kramer, M., Lyne, A. G., ...
We report the detection of radio and X-ray pulsations at a period of 51.6 ms from the X-ray source RX/AX J2229.0+6114 in the error box of the EGRET source 3EG J2227+6122. An ephemeris derived from a...
The First Observations of the Second Brightest Quasar (2001)
Leighly, K. M., Halpern, J. P., Helfand, D. J., Becker, R. H., Impey, C. D.
We report the discovery of a new bright quasar PHL 1811 as part of a followup program to identify bright quasars in the FIRST radio survey. With B=13.9, R=13.9, and z=0.192, this quasar is now the...
The Environments of a Complete, Moderate-Redshift Sample of FIRST Bent-Double Radio Sources (2001)
Blanton, E. L., Gregg, M. D., Helfand, D. J., Becker, R. H., Leighly, K. M.
We present an optical spectroscopic and imaging study of the environments of a complete sample of moderate-redshift, bent-double radio sources. More than half of the forty radio galaxies in the...
The Vela Pulsar and its Synchrotron Nebula (2000)
Helfand, D. J., Gotthelf, E. V., Halpern, J. P.
(Abridged) We present high-resolution Chandra X-ray observations of PSR B0833-45, the 89 ms pulsar associated with the Vela supernova remnant. We have acquired two observations separated by one month...
A Possible X-ray and Radio Counterpart of the High-Energy Gamma-ray Source 3EG J2227+6122 (2000)
Halpern, J. P., Gotthelf, E. V., Leighly, K. M., Helfand, D. J.
The identity of the persistent EGRET sources in the Galactic plane is largely a mystery. For one of these, 3EG J2227+6122, our complete census of X-ray and radio sources in its error circle reveals a...
The FIRST Bright Quasar Survey. II. 60 Nights and 1200 Spectra Later (1999)
White, R. L., Becker, R. H., Gregg, M. D., Laurent-Muehleisen, S. A., Brotherton, M. S., Impey, C. D., ...
We have used the VLA FIRST survey and the APM catalog of the POSS-I plates as the basis for constructing a new radio-selected sample of optically bright quasars. This is the first radio-selected...
FIRST Bent-Double Radio Sources: Tracers of High-Redshift Clusters (1999)
Blanton, E. L., Gregg, M. D., Helfand, D. J., Becker, R. H., White, R. L.
Bent-double radio sources can act as tracers for clusters of galaxies. We present imaging and spectroscopic observations of the environments surrounding ten of these sources (most of them Wide Angle...
Weak Lensing by Large-Scale Structure with the FIRST Radio Survey (1998)
Refregier, A., Brown, S. T., Kamionkowski, M., Helfand, D. J., Cress, C. M., Babul, A., ...
The coherent image distortions induced by weak gravitational lensing can be used to measure the power spectrum of density inhomogeneities in the universe. We present our on-going effort to detect...
The Host Galaxy of the Gamma--Ray Burst 971214 (1998)
Odewahn, S. C., Djorgovski, S. G., Kulkarni, S. R., Dickinson, M., Frail, D. A., Ramaprakash, A. N., ...
We report on Hubble Space Telescope (HST) observations of the host galaxy of GRB 971214, about four months after the burst. The redshift of the proposed host galaxy at z=3.418, combined with optical...
Refregier, A., Helfand, D. J., McMahon, R. G.
Recent ROSAT surveys suggest that galaxies constitute the new class of X-ray sources required to explain the full phenomenology of the cosmic X-Ray Background (XRB). To test this hypothesis, we...
The EINSTEIN Observatory Detection of Faint X-Ray Flashes (1996)
Gotthelf, E. V., Hamilton, T. T., Helfand, D. J.
We report on the result of an extensive search for X-ray counterparts to Gamma Ray Bursts (GRB) using data acquired with the Imaging Proportional Counter (IPC) on-board the Einstein Observatory. We...
The Absence of X-ray Flashes from Nearby Galaxies and the Gamma-Ray Burst Distance Scale (1996)
Hamilton, T. T., Gotthelf, E. V., Helfand, D. J.
If typical gamma-ray bursts (GRBs) have X-ray counterparts similar to those detected by Ginga, then sensitive focusing X-ray telescopes will be able to detect GRBs three orders of magnitude fainter...
The Angular Two-Point Correlation Function for the FIRST Radio Survey (1996)
Cress, C. M., Helfand, D. J., Becker, R. H., Gregg, M. D., White, R. L.
The FIRST (Faint Images of the Radio Sky at Twenty Centimeters) survey now covers 1550 square degrees of sky where $07^{h}16 < \alpha < 17^{h}40$ and $28^{\circ}.3 < \delta < 42^{\circ}$. This yields...
Isolating the Foreground of the X-Ray Background (1995)
Refregier, A., Helfand, D. J., McMahon, R. G.
The foreground component of the X-ray Background (XRB) can be studied by cross-correlating its intensity with galaxy catalogs. We computed the two-point cross-correlation function $W_{xg}$ between 67...
The Angular Two Point Correlation Function for the FIRST Radio Survey - Initial Results (1995)
Cress, C. M., Helfand, D. J., Becker, R. H., White, R. L., Gregg, M. D.
The angular two-point correlation function is calculated for the first 300 square degrees of the FIRST radio survey. Results for various subsamples are also obtained. Double-lobed sources are shown...