H. Thomas Diehl

Discovery of A Very Bright, Strongly-Lensed z=2 Galaxy in the SDSS DR5

We report on the discovery of a very bright z = 2.00 star-forming galaxy that is strongly lensed by a foreground z = 0.422 luminous red galaxy (LRG), SDSS J120602.09+514229.5. This system, nicknamed the Clone, was found in a systematic search for bright arcs lensed by LRGs and brightest cluster galaxies in the Sloan Digital Sky Survey Data Release 5 sample. Follow-up observations on the Subaru 8.2 m telescope on Mauna Kea and the Astrophysical Research Consortium 3.5 m telescope at Apache Point Observatory confirmed the lensing nature of this system. A simple lens model for the system, assuming a singular isothermal ellipsoid mass distribution, yields an Einstein radius of ?Ein = 3.82 ? 003 or 14.8 ? 0.1 h ?1 kpc at the lens redshift. The total projected mass enclosed within the Einstein radius is 2.10 ? 0.03 ? 1012 h ?1 M ?, and the magnification factor for the source galaxy is 27 ? 1. Combining the lens model with our gVriz photometry, we find a (unlensed) star formation rate (SFR) for the source galaxy of 32 h ?1 M ? yr?1, adopting a fiducial constant SFR model with an age of 100 Myr and E(B ? V) = 0.25. With an apparent magnitude of r = 19.8, this system is among the very brightest lensed z ? 2 galaxies, and provides an excellent opportunity to pursue detailed studies of the physical properties of an individual high-redshift star-forming galaxy.

VDES J2325−5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

FO is supported jointly by CAPES (the Science without Borders programme) and the Cambridge Commonwealth Trust. RGM, CAL, MWA, MB, SLR acknowledge the support of UK Science and Technology Research Council (STFC). AJC acknowledges the support of a Raymond and Beverly Sackler visiting fellowship at the Institute of Astronomy. For further information regarding funding please visit the publishers website.

The Sloan Bright Arcs Survey : Six Strongly Lensed Galaxies at z=0.4-1.4

We present new results of our program to systematically search for strongly lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this study six strong lens systems are presented which we have confirmed with followup spectroscopy and imaging using the 3.5m telescope at the Apache Point Observatory. Preliminary mass models indicate that the lenses are group-scale systems with velocity dispersions ranging from 466?878 km s{sup -1} at z = 0.17-0.45 which are strongly lensing source galaxies at z = 0.4-1.4. Galaxy groups are a relatively new mass scale just beginning to be probed with strong lensing. Our sample of lenses roughly doubles the confirmed number of group-scale lenses in the SDSS and complements ongoing strong lens searches in other imaging surveys such as the CFHTLS (Cabanac et al. 2007). As our arcs were discovered in the SDSS imaging data they are all bright (r {approx_equal} 22), making them ideally suited for detailed follow-up studies.

THE SLOAN BRIGHT ARCS SURVEY: DISCOVERY OF SEVEN NEW STRONGLY LENSED GALAXIES FROM z = 0.66-2.94

We report the discovery of seven new, very bright gravitational lens systems from our ongoing gravitational lens search, the Sloan Bright Arcs Survey (SBAS). Two of the systems are confirmed to have high source redshifts z = 2.19 and z = 2.94. Three other systems lie at intermediate redshift with z = 1.33, 1.82, 1.93 and two systems are at low redshift z = 0.66, 0.86. The lensed source galaxies in all of these systems are bright, with i-band magnitudes ranging from 19.73 to 22.06. We present the spectrum of each of the source galaxies in these systems along with estimates of the Einstein radius for each system. The foreground lens in most systems is identified by a red sequence based cluster finder as a galaxy group; one system is identified as a moderately rich cluster. In total, SBAS has now discovered 19 strong lens systems in the SDSS imaging data, 8 of which are among the highest surface brightness z {approx_equal} 2-3 galaxies known.

0.250mm-thick CCD packaging for the Dark Energy Survey Camera array

The Dark Energy Survey Camera focal plane array will consist of 62 2k x 4k CCDs with a pixel size of 15 microns and a silicon thickness of 250 microns for use at wavelengths between 400 and 1000 nm. Bare CCD die will be received from the Lawrence Berkeley National Laboratory (LBNL). At the Fermi National Accelerator Laboratory, the bare die will be packaged into a custom back-side-illuminated module design. Cold probe data from LBNL will be used to select the CCDs to be packaged. The module design utilizes an aluminum nitride readout board and spacer and an Invar foot. A module flatness of 3 microns over small (1 sqcm) areas and less than 10 microns over neighboring areas on a CCD are required for uniform images over the focal plane. A confocal chromatic inspection system is being developed to precisely measure flatness over a grid up to 300 x 300 mm. This system will be utilized to inspect not only room-temperature modules, but also cold individual modules and partial arrays through flat dewar windows.

Assembly of the Dark Energy Survey CCD Imager

The Dark Energy Camera (DECam) is the new wide field prime-focus imager for the Blanco 4m telescope at CTIO. This instrument is a 2.2 sq. deg. camera with a 45 cm diameter focal plane consisting of 62 2k × 4k CCDs and 12 2k × 2k CCDs and was developed for the Dark Energy Survey that will start operations at CTIO in 2011. DECam includes the vessel shell, the optical window cell, the CCDs with their readout electronics and vacuum interface, the focal plane support plate and its mounts, and the cooling system and thermal controls. Assembly of the imager, alignment of the focal plane and installation of the CCDs are described. During DECam development a full scale prototype was used for multi-CCD readout tests. This test vessel went through several stages as the CCDs and related hardware progressed from early prototypes to final production designs.

Transport and Installation of the Dark Energy Survey CCD Imager

The Dark Energy Survey CCD imager was constructed at the Fermi National Accelerator Laboratory and delivered to the Cerro Tololo Inter-American Observatory in Chile for installation onto the Blanco 4m telescope. Several efforts are described relating to preparation of the instrument for transport, development and testing of a shipping crate designed to minimize transportation loads transmitted to the camera, and inspection of the imager upon arrival at the observatory. Transportation loads were monitored and are described. For installation of the imager at the telescope prime focus, where it mates with its previously-installed optical corrector, specialized tooling was developed to safely lift, support, and position the vessel. The installation and removal processes were tested on the Telescope Simulator mockup at FNAL, thus minimizing technical and schedule risk for the work performed at CTIO. Final installation of the imager is scheduled for August 2012.

Measuring the flatness of focal plane for very large mosaic CCD camera

Large mosaic multiCCD camera is the key instrument for modern digital sky survey. DECam is an extremely red sensitive 520 Megapixel camera designed for the incoming Dark Energy Survey (DES). It is consist of sixty two 4k2k and twelve 2k2k 250-micron thick fully-depleted CCDs, with a focal plane of 44 cm in diameter and a eld of view of 2.2 square degree. It will be attached to the Blanco 4-meter telescope at CTIO. The DES will cover 5000 square-degrees of the southern galactic cap in 5 color bands (g, r, i, z, Y) in 5 years starting from 2011. To achieve the science goal of constraining the Dark Energy evolution, stringent requirements are laid down for the design of DECam. Among them, the atness of the focal plane needs to be controlled within a 60-micron envelope in order to achieve the specied PSF variation limit. It is very challenging to measure the atness of the focal plane to such precision when it is placed in a high vacuum dewar at 173 K. We developed two image based techniques to measure the atness of the focal plane. By imaging a regular grid of dots on the focal plane, the CCD oset along the optical axis is converted to the variation the grid spacings at dierent positions on the focal plane. After extracting the patterns and comparing the change in spacings, we can measure the atness to high precision. In method 1, the regular dots are kept in high sub micron precision and cover the whole focal plane. In method 2, no high precision for the grid is required. Instead, we use a precise XY stage moves the pattern across the whole focal plane and comparing the variations of the spacing when it is imaged by dierent CCDs. Simulation and real measurements show that the two methods work very well for our purpose, and are in good agreement with the direct optical measurements.

Core or Cusps: The Central Dark Matter Profile of a Strong Lensing Cluster with a Bright Central Image at Redshift 1

We report on SPT-CLJ2011-5228, a giant system of arcs created by a cluster at

The Dark Energy Spectrometer-A Potential Multi-Fiber Instrument for the Blanco 4-meter Telescope

z=1.06