Suyu, S. H., Marshall, P. J., Auger, M. W., Hilbert, S., Blandford, R. D., Koopmans, L. V. E., ...
Strong gravitational lens systems with measured time delays between the multiple images provide a method for measuring the ``time-delay distance'' to the lens, and thus the Hubble constant. We...
McKean, J. P., Auger, M. W., Koopmans, L. V. E., Vegetti, S., Czoske, O., Fassnacht, C. D., ...
The gravitational lens system CLASS B2108+213 has two radio-loud lensed images separated by 4.56 arcsec. The relatively large image separation implies that the lensing is caused by a group of...
Galaxy Number Counts and Implications for Strong Lensing (2009)
Fassnacht, C. D., Koopmans, L. V. E., Wong, K. C.
We compare galaxy number counts in Advanced Camera for Surveys (ACS) fields containing moderate-redshift (0.2
Lemaux, B. C., Lubin, L. M., Sawicki, M., Martin, C., Lagattuta, D. J., Gal, R. R., ...
We present results of a spectroscopic search for Lyα emitters (LAEs) in the Cl1604 supercluster field using the extensive spectroscopic Keck/DEep Imaging Multi-Object Spectrograph database taken as...
Identifying Compact Symmetric Objects from the VLBA Imaging and Polarization Survey (2009)
Tremblay, S. E., Taylor, G. B., Helmboldt, J. F., Fassnacht, C. D., Romani, R. W.
Compact Symmetric Objects (CSOs) are small (less than 1 kpc) radio sources which have symmetric double lobes or jets. The dominant theory for the small size of these objects is that they are young...
Strong Gravitational Lensing as a Probe of Gravity, Dark-Matter and Super-Massive Black Holes (2009)
Koopmans, L. V. E., Auger, M., Barnabe, M., Bolton, A., Bradac, M., Ciotti, L., ...
Whereas considerable effort has been afforded in understanding the properties of galaxies, a full physical picture, connecting their baryonic and dark-matter content, super-massive black holes, and...
Dark Matter Structures in the Universe: Prospects for Optical Astronomy in the Next Decade (2009)
Marshall, P. J., Auger, M., Bartlett, J. G., Bradac, M., Cooray, A., Dalal, N., ...
The Cold Dark Matter theory of gravitationally-driven hierarchical structure formation has earned its status as a paradigm by explaining the distribution of matter over large spans of cosmic distance...
Dissecting the Gravitational Lens B1608+656. I. Lens Potential Reconstruction (2009)
Suyu, S. H., Marshall, P. J., Blandford, R. D., Fassnacht, C. D., Koopmans, L. V. E., McKean, J. P., ...
Strong gravitational lensing is a powerful technique for probing galaxy mass distributions and for measuring cosmological parameters. Lens systems with extended source-intensity distributions are...
Perley, D. A., Li, W., Chornock, R., Prochaska, J. X., Butler, N. R., Chandra, P., ...
The optical afterglow of long-duration GRB 071003 is among the brightest yet to be detected from any GRB, with R ≈ 12 mag in KAIT observations starting 42 s after the GRB trigger, including...
A shrinking compact symmetric object: J11584+2450? (2008)
Tremblay, S. E., Taylor, G. B., Helmboldt, J. F., Fassnacht, C. D., Pearson, T. J.
We present multifrequency, multiepoch, Very Long Baseline Array (VLBA) observations of J11584+2450. These observations clearly show this source, previously classified as a core jet, to be a compact...
A shrinking Compact Symmetric Object: J11584+2450? (2008)
Tremblay, S. E., Taylor, G. B., Helmboldt, J. F., Fassnacht, C. D., Pearson, T. J.
We present multi-frequency multi-epoch Very Long Baseline Array (VLBA) observations of J11584+2450. These observations clearly show this source, previously classified as a core-jet, to be a compact...
Perley, D. A., Li, W., Chornock, R., Prochaska, J. X., Butler, N. R., Chandra, P., ...
The optical afterglow of long-duration GRB 071003 is among the brightest yet to be detected from any GRB, with R ~ 12 mag in KAIT observations starting 42 s after the GRB trigger, including filtered...
Dissecting the Gravitational Lens B1608+656. I. Lens Potential Reconstruction (2008)
Suyu, S. H., Marshall, P. J., Blandford, R. D., Fassnacht, C. D., Koopmans, L. V. E., McKean, J. P., ...
Strong gravitational lensing is a powerful technique for probing galaxy mass distributions and for measuring cosmological parameters. We present a pixelated approach to modeling simultaneously the...
Lens galaxy properties of SBS 1520+530 : insights from Keck spectroscopy and AO imaging (2008)
Auger, M. W., Fassnacht, C. D., Wong, K. C., Thompson, D., Matthews, K., Soifer, B. T.
We report on an investigation of the SBS 1520+530 gravitational lens system. We have used archival Hubble Space Telescope (HST) imaging, Keck spectroscopic data, and Keck adaptive optics (AO) imaging...
The Environments of Low and High Luminosity Radio Galaxies at Moderate Redshifts (2008)
Auger, M. W., Becker, R. H., Fassnacht, C. D.
In the local Universe, high-power radio galaxies live in lower density environments than low-luminosity radio galaxies. If this trend continues to higher redshifts, powerful radio galaxies would...
Probing a massive radio galaxy with gravitational lensing (2007)
More, A., McKean, J. P., Muxlow, T. W. B., Porcas, R. W., Fassnacht, C. D., Koopmans, L. V. E.
The gravitational lens system CLASS B2108+213 has two lensed images separated by 4.56 arcsec. Such a wide image separation suggests that the lens is either a massive galaxy, or is composed of a group...
Astronomy And Astrophysics (2007)
Lensing Galaxies Light, N. Jackson, P. Helbig, C. D. Fassnacht, L. Koopmans, ...
. In a recent paper, Hawkins (1997) argues on the basis of statistical studies of double-image gravitational lenses and lens candidates that a large population of dark lenses exists and that these...
With The Class, C. D. Fassnacht, T. J. Pearson, ...
We present the results of a program to monitor the four-image gravitational lens B1608+656 with the VLA. The system was observed over a seven month period from 1996 October to 1997 May. The 64 epochs...
Fassnacht, C. D., Kocevski, D. D., Auger, M. W., Lubin, L. M., Neureuther, J. L., Jeltema, T. E., ...
We present results from a systematic investigation of the X-ray properties of a sample of moderate redshift (0.3
Lens Galaxy Properties of SBS1520+530: Insights from Keck Spectroscopy and AO Imaging (2007)
Auger, M. W., Fassnacht, C. D., Wong, K. C., Thomspon, D., Matthews, K., Soifer, B. T.
We report on an investigation of the SBS 1520+530 gravitational lens system and its environment using archival HST imaging, Keck spectroscopic data, and Keck adaptive-optics imaging. The AO imaging...
Characteristics of EGRET Blazars in the VLBA Imaging and Polarimetry Survey (VIPS) (2007)
Taylor, G. B., Healey, S. E., Helmboldt, J. F., Tremblay, S., Fassnacht, C. D., Walker, R. C., ...
We examine the radio properties of EGRET-detected blazars observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). VIPS has a flux limit roughly an order of magnitude below the MOJAVE...
Gravitational lensing by Elliptical Galaxies, and the Schwarz Function (2007)
Fassnacht, C. D., Keeton, C. R., Khavinson, D.
We discuss gravitational lensing by elliptical galaxies with some particular mass distributions. Using simple techniques from the theory of quadrature domains and the Schwarz function (cf. \cite{Sh})...
Auger, M. W., Fassnacht, C. D., Abrahamse, A. L., Lubin, L. M., Squires, G. K.
We report on the results of a spectroscopic survey of the environments of the gravitational lens systems CLASS B1600+434 (z_l = 0.41, z_s = 1.59) and CLASS B2319+051 (z_l = 0.62). The B1600+434...
The Cosmic Lens All-Sky Survey parent population - I. Sample selection and number counts (2007)
McKean, J. P., Browne, I. W. A., Jackson, N. J., Fassnacht, C. D., Helbig, P.
We present the selection of the Jodrell Bank Flat-spectrum (JBF) radio source sample, which is designed to reduce the uncertainties in the Cosmic Lens All-Sky Survey (CLASS) gravitational lensing...
The VLBA Imaging and Polarimetry Survey at 5 GHz (2006)
Helmboldt, J. F., Taylor, G. B., Tremblay, S., Fassnacht, C. D., Walker, R. C., Myers, S. T., ...
We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5 GHz VLBI survey of 1,127 sources with flat radio spectra. Through automated data reduction and imaging routines, we...
McKean, J. P., Koopmans, L. V. E., Flack, C. E., Fassnacht, C. D., Thompson, D., Matthews, K., ...
The existence of flux-ratio anomalies between fold and cusp images in galaxy-scale strong-lens systems has led to an interpretation based on the presence of a high mass-fraction of cold-dark-matter...
A Strong-Lens Survey in AEGIS: the influence of large scale structure (2006)
Moustakas, L. A., Marshall, P. J., Newman, J. A., Coil, A. L., Cooper, M. C., Davis, M., ...
We report on the results of a visual search for galaxy-scale strong gravitational lenses over 650 arcmin^2 of HST/ACS imaging in the DEEP2-EGS field. In addition to a previously-known Einstein Cross...
Fassnacht, C. D., McKean, J. P., Koopmans, L. V. E., Treu, T., Blandford, R. D., Auger, M. W., ...
We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble...
Auger, M. W., Fassnacht, C. D., Abrahamse, A. L., Lubin, L. M., Squires, G. K.
We report on the results of a spectroscopic survey of the environments of the gravitational lens systems CLASS B1600+434 (z_l = 0.41, z_s = 1.59) and CLASS B2319+051 (z_l = 0.62). The B1600+434...
Fassnacht, C. D., Gal, R. R., Lubin, L. M., McKean, J. P., Squires, G. K., Readhead, A. C. S.
We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z = 0.631) and...
Faint Radio Sources in the NOAO Bootes Field. VLBA Imaging and Optical Identifications (2005)
Wrobel, J. M., Taylor, G. B., Rector, T. A., Myers, S. T., Fassnacht, C. D.
As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0 GHz to obtain phase-referenced images of 76...
CLASS B0631+519: Last of the CLASS lenses (2005)
York, T., Jackson, N., Browne, I. W. A., Koopmans, L. V. E., McKean, J. P., Norbury, M. A., ...
We report the discovery of a new gravitational lens system from the CLASS survey, CLASS B0631+519. VLA, MERLIN and VLBA observations show a doubly-imaged radio core, a doubly-imaged lobe and a second...
VLBA Imaging Polarimetry of Active Galactic Nuclei - An Automated Approach (2005)
Taylor, G. B., Fassnacht, C. D., Sjouwerman, L. O., Myers, S. T., Ulvestad, J. S., Walker, R. C., ...
We present full polarization Very Long Baseline Array (VLBA) observations at 5 GHz and 15 GHz of 24 compact active galactic nuclei (AGN). These sources were observed as part of a pilot project to...
CLASS B2108+213: A new wide separation gravitational lens system (2004)
McKean, J. P., Browne, I. W. A., Jackson, N. J., Koopmans, L. V. E., Norbury, M. A., Treu, T., ...
We present observations of CLASS B2108+213, the widest separation gravitational lens system discovered by the Cosmic Lens All-Sky Survey. Radio imaging using the VLA at 8.46 GHz and MERLIN at 5 GHz...
Active Galaxies at Milliarcsecond Resolution in the NOAO Deep Wide-Field Survey (2004)
Wrobel, J. M., Rector, T. A., Taylor, G. B., Myers, S. T., Fassnacht, C. D.
We are using the NRAO VLBA at 5.0 GHz to image about 200 FIRST sources stronger than 10 mJy at 1.4 GHz in the NDWFS.
Keck spectroscopy of CLASS gravitational lenses (2004)
McKean, J. P, Koopmans, L. V. E., Browne, I. W. A., Fassnacht, C. D., Blandford, R. D., Lubin, L. M., ...
We present the optical spectra of four newly discovered gravitational lenses from the Cosmic Lens All-Sky Survey (CLASS). These observations were carried out using the Low Resolution Imaging...
Strong Gravitational Lens Candidates in the GOODS ACS Fields (2003)
Fassnacht, C. D., Moustakas, L. A., Casertano, S., Ferguson, H. C., Lucas, R. A., Park, Y.
We present results from a systematic search for strong gravitational lenses in the GOODS ACS data. The search technique involves creating a sample of likely lensing galaxies, which we define as...
The Hubble Constant from the Gravitational Lens B1608+656 (2003)
Koopmans, L. V. E., Treu, T., Fassnacht, C. D., Blandford, R. D., Surpi, G.
We present a refined gravitational lens model of the four-image lens system B1608+656 based on new and improved observational constraints: (i) the three independent time-delays and flux-ratios from...
The Cosmic Lens All-Sky Survey:II. Gravitational lens candidate selection and follow-up (2002)
Browne, I. W. A., Wilkinson, P. N., Jackson, N. J. F., Myers, S. T., Fassnacht, C. D., Koopmans, L. V. E., ...
We report the final results of the search for gravitationally lensed flat-spectrum radio sources found in the combination of CLASS (Cosmic Lens All Sky Survey) and JVAS (Jodrell-Bank VLA Astrometric...
The Cosmic Lens All-Sky Survey: I. Source selection and observations (2002)
Myers, S. T., Jackson, N. J., Browne, I. W. A., De Bruyn, A. G., Pearson, T. J., Readhead, A. C. S., ...
The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program which has obtained high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the...
B0850+054: a new gravitational lens system from CLASS (2002)
Biggs, A. D., Rusin, D., Browne, I. W. A., De Bruyn, A. G., Jackson, N. J., Koopmans, L. V. E., ...
We report the discovery of a new gravitational lens system from the CLASS survey. Radio observations with the VLA, the WSRT and MERLIN show that the radio source B0850+054 is comprised of two compact...
CLASS B0445+123 : a new two-image gravitational lens system (2002)
Norbury, M. A., Myers, S. T., Marlow, D. R., Koopmans, L. V. E., Fassnacht, C. D., Chae, K. H., ...
Submitted to: Mon. Not. R. Astron. Soc. Abstract: A new two-image gravitational lens system has been discovered as a result of the Cosmic Lens All-Sky Survey (CLASS). Radio observations with the VLA,...
CLASS B0445+123: a new two-image gravitational lens system (2002)
Argo, M. K., Jackson, N. J., Browne, I. W. A., York, T., McKean, J. P., Biggs, A. D., ...
A new two-image gravitational lens system has been discovered as a result of the Cosmic Lens All-Sky Survey (CLASS). Radio observations with the VLA, MERLIN and the VLBA at increasingly higher...
Biggs, A. D., Blandford, R. D., Browne, I. W. A., De Bruyn, A. G., Fassnacht, C. D., ...
We derive constraints on cosmological parameters and the properties of the lensing galaxies from gravitational lens statistics based on the final Cosmic Lens All Sky Survey (CLASS) data. For a flat...
Fassnacht, C. D., Xanthopoulos, E., Koopmans, L. V. E., Rusin, D.
The gravitational lens CLASS B1608+656 is the only four-image lens system for which all three independent time delays have been measured. This makes the system an excellent candidate for a...
Fassnacht, C. D., Lubin, L. M.
Previous observations of the environments of the lensing galaxies in gravitational lens systems suggest that many of the lensing galaxies are associated with small groups of galaxies. As a result, we...
Compact Symmetric Objects as Radio Flux Density Calibrators (2001)
Fassnacht, C. D., Taylor, G. B.
We present results from the first intensive monitoring campaign of a sample of Compact Symmetric Objects (CSOs). We observed seven CSOs at 8.5 GHz over a period of eight months, with an average...
The new two-image gravitational lens system CLASS B2319+051 (2001)
Rusin, D., Marlow, D. R., Norbury, M., Browne, I. W. A., Jackson, N., Wilkinson, P. N., ...
We report the discovery of a new two-image gravitational lens system from the Cosmic Lens All-Sky Survey, CLASS B2319+051. Radio imaging with the Very Large Array (VLA) and Multi-Element Radio-Linked...
The Inner Light Year of the Nearest Seyfert 1 Nucleus in NGC 4395 (2001)
Wrobel, J. M., Fassnacht, C. D., Ho, L. C.
The NRAO VLBA was used at 1.4 GHz to image the inner 550 mas (23 lt-years) of the nearest known Seyfert 1 nucleus, in the Sm galaxy NGC 4395. One continuum source was detected, with flux density...
Radio Microlensing: Past, Present & Near Future (2000)
Koopmans, L. V. E., De Bruyn, A. G., Fassnacht, C. D., Wambsganss, J., Blandford, R. D., Collaboration, + CLASS
Strongly correlated non-intrinsic variability between 5 and 8.5 GHz has been observed in one of the lensed images of the gravitational lens B1600+434. These non-intrinsic (i.e. `external') variations...
A New Quadruple Gravitational Lens System: CLASS B0128+437 (2000)
Phillips, P. M., Norbury, M. A., Koopmans, L. V. E., Browne, I. W. A., Jackson, N. J., Wilkinson, P. N., ...
High resolution MERLIN observations of a newly-discovered four-image gravitational lens system, B0128+437, are presented. The system was found after a careful re-analysis of the entire CLASS dataset....
CLASS B0739+366: A new two-image gravitational lens system (2000)
Marlow, D. R., Rusin, D., Norbury, M., Jackson, N., Browne, I. W. A., Wilkinson, P. N., ...
We present the discovery of CLASS B0739+366, a new gravitational lens system from the Cosmic Lens All-Sky Survey. Radio imaging of the source with the Very Large Array (VLA) shows two compact...
CLASS B0827+525: `Dark lens' or binary radio-loud quasar? (2000)
Koopmans, L. V. E., De Bruyn, A. G., Fassnacht, C. D., Marlow, D. R., Rusin, D., Blandford, R. D., ...
We present radio, optical, near-infrared and spectroscopic observations of the source B0827+525. We consider this source as the best candidate from the Cosmic Lens All-Sky Survey (CLASS) for a `dark...
VLA 8.4-GHz monitoring observations of the CLASS gravitational lens B1933+503 (2000)
Biggs, A. D., Xanthopoulos, E., Browne, I. W. A., Koopmans, L. V. E., Fassnacht, C. D.
The complex ten-component gravitational lens system B1933+503 has been monitored with the VLA during the period February to June 1998 with a view to measuring the time delay between the four compact...
VLA 8.4-GHz monitoring observations of the CLASS gravitational lens B1933+503 (2000)
Fassnacht, C. D., Koopmans, L. V. E., Browne, I. W. A., Xanthopoulos, E., Biggs, A. D.
Submitted to: Mon. Not. R. Astron. Soc. Abstract: The complex ten-component gravitational lens system B1933+503 has been monitored with the VLA during the period February to June 1998 with a view to...
A radio-microlensing caustic crossing in B1600+434? (2000)
Koopmans, L. V. E., De Bruyn, A. G., Wambsganss, J., Fassnacht, C. D.
First, we review the current status of the detection of strong `external' variability in the CLASS gravitational B1600+434, focusing on the 1998 VLA 8.5-GHz and 1998/9 WSRT multi-frequency...
A time-delay determination from VLA light curves of the CLASS gravitational lens B1600+434 (2000)
Koopmans, L. V. E., De Bruyn, A. G., Xanthopoulos, E., Fassnacht, C. D.
We present Very Large Array (VLA) 8.5-GHz light curves of the two lens images of the Cosmic Lens All Sky Survey (CLASS) gravitational lens B1600+434. We find a nearly linear decrease of 18-19% in the...
Redshifts and Neutral Hydrogen Observations of Compact Symmetric Objects in the COINS Sample (1999)
Peck, A. B., Taylor, G. B., Fassnacht, C. D., Readhead, A. C. S., Vermeulen, R. C.
Compact Symmetric Objects (CSOs) are young radio galaxies whose jet axes lie close to the plane of the sky, and whose appearance is therefore not dominated by relativistic beaming effects. The small...
Lubin, L. M., Fassnacht, C. D., Readhead, A. C. S., Blandford, R. D., Kundic, T.
We present new results from a continuing Keck program to study gravitational lens systems. We have obtained redshifts for three lens systems, SBS 0909+532, HST 1411+5211, and CLASS B2319+051. For all...
Measuring H_0 with CLASS B1608+656: The Second Season of VLA Monitoring (1999)
Fassnacht, C. D., Xanthopoulos, E., Koopmans, L. V. E., Pearson, T. J., Readhead, A. C. S., Myers, S. T.
The four-component gravitational lens CLASS B1608+656 has been monitored with the VLA for two seasons in order to search for time delays between the components. These time delays can be combined with...
Fassnacht, C. D., Pearson, T. J., Readhead, A. C. S., Browne, I. W. A., Koopmans, L. V. E., Myers, S. T., ...
We present the results of a program to monitor the four-image gravitational lens B1608+656 with the VLA. The system was observed over a seven month period from 1996 October to 1997 May. The 64 epochs...
Koopmans, L. V. E., Fassnacht, C. D.
EDITED FROM PAPER: We present mass models of the four-image gravitational lens system B1608+656. A mass model for the lens galaxies has been determined that reproduces the image positions, two out of...
Myers, S. T., Rusin, D., Fassnacht, C. D., Blandford, R. D., Pearson, T. J., Readhead, A. C. S., ...
The third phase of the Cosmic Lens All-Sky Survey (CLASS) has recently been completed, bringing the total number of sources imaged to over 15000 in the CLASS and JVAS combined survey. In the VLA...
Measuring Cosmological Parameters with the JVAS and CLASS Gravitational Lens Surveys (1999)
Helbig, P., Blandford, R. D., Browne, I. W. A., De Bruyn, A. G., Fassnacht, C. D., Jackson, N., ...
The JVAS (Jodrell Bank-VLA Astrometric Survey) and CLASS (Cosmic Lens All-Sky Survey) are well-defined surveys containing about ten thousand flat-spectrum radio sources. For many reasons,...
A new radio double lens from CLASS: B1127+385 (1998)
Koopmans, L. V. E., De Bruyn, A. G., Marlow, D. R., Jackson, N., Blandford, R. D., Browne, I. W. A., ...
We present the discovery of a new gravitational lens system with two compact radio images separated by 0.701+-0.001 arcsec. The lens system was discovered in the Cosmic Lens All Sky Survey (CLASS) as...
B2045+265: A New Four-Image Gravitational Lens from CLASS (1998)
Fassnacht, C. D., Blandford, R. D., Cohen, J. G., Matthews, K., Pearson, T. J., Readhead, A. C. S., ...
We have discovered a new gravitational lens in the Cosmic Lens All-Sky Survey (CLASS). B2045+265 is a four-image system with a maximum separation of 1.9 arcsec. A fifth radio component is detected,...
Lensing galaxies : light or dark? (1998)
Marlow, D. R., Koopmans, L. V. E., Fassnacht, C. D., Browne, I. W. A., Helbig, P., Jackson, N., ...
Submitted to: Astron. Astrophys. Abstract: In a recent paper, Hawkins (1997) argues on the basis of statistical studies of double-image gravitational lenses and lens candidates that a large...
Lensing galaxies: light or dark? (1998)
Jackson, N., Helbig, P., Browne, I. W. A., Fassnacht, C. D., Koopmans, L. V. E., Marlow, D. R., ...
In a recent paper, Hawkins (1997) argues on the basis of statistical studies of double-image gravitational lenses and lens candidates that a large population of dark lenses exists and that these...
Fassnacht, C. D., Cohen, J. G.
We present spectra of three gravitational lens systems taken with the Low Resolution Imaging Spectrograph on the W. M. Keck Telescopes. All of the systems were discovered in the JVAS and CLASS radio...
The complex gravitational lens system B1933+503 (1997)
Sykes, C. M., Browne, I. W. A., Jackson, N. J., Marlow, D. R., Nair, S., Wilkinson, P. N., ...
We report the discovery of the most complex arcsec-scale radio gravitational lens system yet known. B1933+503 was found during the course of the CLASS survey and MERLIN and VLA radio maps reveal up...
A candidate gravitational lens in the Hubble Deep Field (1996)
Hogg, David W., Blandford, Roger, Kundić, Tomislav, Fassnacht, C. D., Malhotra, Sangeeta
The discovery of HDF~J123652+621227, a candidate gravitational lens in the HDF, is reported. This lens may be multiply imaging several optical sources at different redshifts. If follow-up...