B. A. McLeod
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View article: Off-axis Hartmann wavefront sensing for the GMT-Consortium Large Earth Finder (G-CLEF) red camera optics
Off-axis Hartmann wavefront sensing for the GMT-Consortium Large Earth Finder (G-CLEF) red camera optics Open
The Hartmann test is a method used to measure the wavefront error in a focal optical system, wherein a mask with a pattern of small holes is placed at the system's aperture stop. By taking an image at a defocused plane, the differences bet…
View article: Giant Magellan Telescope Adaptive Optics Overview
Giant Magellan Telescope Adaptive Optics Overview Open
The 25.4 m diameter Giant Magellan Telescope will have four first-generation observing modes: Natural seeing, ground- layer AO, natural guide star AO, and laser tomography AO. These control modes are enabled by a suite of wavefront sensors…
View article: The wide field phasing testbed for the Giant Magellan Telescope
The wide field phasing testbed for the Giant Magellan Telescope Open
Phasing the seven segment pairs of the doubly segmented Giant Magellan Telescope over an extended field of view requires measuring wavefront piston at multiple field locations. This will be done using a dispersed fringe sensor in each of f…
View article: Closed–loop Optical Integrated Modeling
Closed–loop Optical Integrated Modeling Open
Adaptive optics has long been an add-on instrument attached to telescopes.Nowadays, with the development of adaptive secondary mirrors, AO is increasingly becoming a part of the telescope itself.As such, AO must now be included at a very e…
View article: Phasing the GMT with a next generation e-APD dispersed fringe sensor: design and on-sky prototyping
Phasing the GMT with a next generation e-APD dispersed fringe sensor: design and on-sky prototyping Open
The GMT will be a 25.4-meter telescope consisting of 7 primary and secondary mirror segments that must be phased to within a fraction of an imaging wavelength in order to achieve diffraction limited performance.The need to use off-axis gui…
View article: The Giant Magellan Telescope Phasing System: algorithms and performance simulations
The Giant Magellan Telescope Phasing System: algorithms and performance simulations Open
The 25.4m Giant Magellan Telescope (GMT) consists of seven 8.4 m primary mirror (M1) segments with matching segmentation of the Gregorian secondary mirror (M2).When operating the telescope in the diffraction-limited Adaptive Optics (AO) ob…
View article: On-sky demonstration of the GMT dispersed fringe phasing sensor prototype on the Magellan Telescope
On-sky demonstration of the GMT dispersed fringe phasing sensor prototype on the Magellan Telescope Open
The GMT is an aplanatic Gregorian telescope consisting of 7 primary and secondary mirror segments that must be phased to within a fraction of an imaging wavelength to allow the 25.4 meter telescope to reach its diffraction limit. When oper…
View article: Mitigation of H2RG persistence with image illumination
Mitigation of H2RG persistence with image illumination Open
Residual charge generation, or image persistence, in infrared detectors is a problem that affects many low-light astronomical instruments. The HAWAII-2RG in the MMT and Magellan Infrared Spectrograph shows significant persistence when firs…
View article: THE EXTENDED HALO OF CENTAURUS A: UNCOVERING SATELLITES, STREAMS, AND SUBSTRUCTURES*
THE EXTENDED HALO OF CENTAURUS A: UNCOVERING SATELLITES, STREAMS, AND SUBSTRUCTURES* Open
We present the widest-field resolved stellar map to date of the closest ( Mpc) massive elliptical galaxy NGC 5128 (Centaurus A; Cen A), extending out to a projected galactocentric radius of ∼150 kpc. The data set is part of our ongoing Pan…
View article: A TIDALLY DISRUPTING DWARF GALAXY IN THE HALO OF NGC 253
A TIDALLY DISRUPTING DWARF GALAXY IN THE HALO OF NGC 253 Open
We report the discovery of Scl-MM-Dw2, a new dwarf galaxy at a projected separation of ∼50 kpc from NGC 253, as part of the Panoramic Imaging Survey of Centaurus and Sculptor project (PISCeS). We measure a tip of the red giant branch (RGB)…
View article: Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey
Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey Open
In the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), we investigate the resolved stellar halos of two nearby galaxies (the elliptical Centaurus A and the spiral Sculptor, D $\sim3.7$ Mpc) out to a projected galact…
View article: Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey
Resolving the extended stellar halos of nearby galaxies: the wide-field PISCeS survey Open
In the wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), we investigate the resolved stellar halos of two nearby galaxies (the elliptical Centaurus A and the spiral Sculptor, D ~ 3.7 Mpc) out to a projected galactocen…
View article: Megacam: A Wide-Field CCD Imager for the MMT and Magellan
Megacam: A Wide-Field CCD Imager for the MMT and Magellan Open
Megacam is a large-format optical camera that can be operated at the f/5 Cassegrain foci of the MMT on Mount Hopkins, Arizona, and the Magellan Clay telescope at Las Campanas Observatory, Chile. Megacam's focal plane is composed of 36 clos…
View article: Wavefront control simulations for the Giant Magellan Telescope: Field-dependent segment piston control
Wavefront control simulations for the Giant Magellan Telescope: Field-dependent segment piston control Open
We present in this paper preliminary simulation results aimed at validating the GMT piston control strategy. Wewill in particular consider an observing mode in which an Adaptive Optics (AO) system is providing fast on-axisWF correction wit…
View article: Prototyping the GMT phasing camera with the Magellan AO system
Prototyping the GMT phasing camera with the Magellan AO system Open
The future diffraction-limited performance of the 25.4 meter Giant Magellan Telescope (GMT) will rely on the activeand adaptive wavefront sensing measurements made by the Acquisition, Guiding, and Wavefront Sensor (AGWS)currently being des…
View article: The GMT Dynamic Optical Simulation
The GMT Dynamic Optical Simulation Open
The Giant Magellan Telescope (GMT) is a gregorian 25.5-meter diameter primary mirror (M1) made of 7 8.4-meter diameter circular aspheric segments. The secondary mirror (M2) is a 1/8th down-scale model of M1 madeof 7 1- meter diameter segme…
View article: Measuring Segment Piston with a Dispersed Fringe Sensor on the Giant Magellan Telescope
Measuring Segment Piston with a Dispersed Fringe Sensor on the Giant Magellan Telescope Open
The Giant Magellan Telescope (GMT) consists of seven 8.365 m segments with a separation of 0.345 m. A uniquechallenge for GMT lies in phasing these segments and, in particular, how to measure segment piston optically.Making segment piston …