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Your search keyword '"Percival, J. A."' showing total 722 results
Start Over Author "Percival, J. A."
722 results on '"Percival, J. A."'

8. Geological and geochemical data from Mackenzie corridor. Part XI: New geochemical, magnetic susceptibility, and X-ray diffraction data from the Horn River Group (Devonian) in cores and outcrops south of Norman Wells, Northwest Territories

Author

Kabanov, P B, primary, Abdi, W, additional, Biggin, A J, additional, Bilot, I, additional, van derBoon, A, additional, Gouwy, S, additional, Grasby, S, additional, Minions, N, additional, Percival, J, additional, Thallner, D, additional, Twemlow, C, additional, and VandenBerg, R, additional

Published
2022
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21. Neoproterozoic-hosted Carlin-type mineralization in central Yukon, part 2: mineralization

Author

Pinet, N, primary, Sack, P, additional, Mercier-Langevin, P, additional, Davis, WJ, additional, Lavoie, D, additional, Ardakani, OH, additional, Komaromi, BA, additional, Dubé, B, additional, Cline, J S, additional, Petts, D C, additional, Jautzy, J, additional, Jackson, S E, additional, Percival, J B, additional, Savard, M M, additional, and Brake, V I, additional

Published
2020
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32. The MaNGA Integral Field Unit Fiber Feed System for the Sloan 2.5 m Telescope

Author

Drory, N., MacDonald, N., Bershady, M. A., Bundy, K., Gunn, J., Law, D. R., Smith, M., Stoll, R., Tremonti, C. A., Wake, D. A., Yan, R., Weijmans, A. M., Byler, N., Cherinka, B., Cope, F., Eigenbrot, A., Harding, P., Holder, D., Huehnerhoff, J., Jaehnig, K., Jansen, T. C., Klaene, M., Paat, A. M., Percival, J., and Sayres, C.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe the design, manufacture, and performance of bare-fiber integral field units (IFUs) for the SDSS-IV survey MaNGA (Mapping Nearby Galaxies at APO) on the the Sloan 2.5 m telescope at Apache Point Observatory (APO). MaNGA is a luminosity-selected integral-field spectroscopic survey of 10,000 local galaxies covering 360-1030 nm at R ~ 2200. The IFUs have hexagonal dense packing of fibers with packing regularity of 3 um (RMS), and throughput of 96+/-0.5% from 350 nm to 1 um in the lab. Their sizes range from 19 to 127 fibers (3-7 hexagonal layers) using Polymicro FBP 120:132:150 um core:clad:buffer fibers to reach a fill fraction of 56%. High throughput (and low focal-ratio degradation) is achieved by maintaining the fiber cladding and buffer intact, ensuring excellent surface polish, and applying a multi-layer AR coating of the input and output surfaces. In operations on-sky, the IFUs show only an additional 2.3% FRD-related variability in throughput despite repeated mechanical stressing during plate plugging (however other losses are present). The IFUs achieve on-sky throughput 5% above the single-fiber feeds used in SDSS-III/BOSS, attributable to equivalent performance compared to single fibers and additional gains from the AR coating. The manufacturing process is geared toward mass-production of high-multiplex systems. The low-stress process involves a precision ferrule with hexagonal inner shape designed to lead inserted fibers to settle in a dense hexagonal pattern. The ferrule inner diameter is tapered at progressively shallower angles toward its tip and the final 2 mm are straight and only a few um larger than necessary to hold the desired number of fibers. This process scales to accommodate other fiber sizes and to IFUs with substantially larger fiber count. (Abridged), Comment: 23 pages, 30 figures, AJ accepted

Published
2014
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41. Mineralogy, petrography and autoradiography of selected samples from the Contact Lake and NICO areas, Great Bear Magmatic Zone, Northwest Territories (IOCG-GEM Project)

Author

Percival, J B, primary, Potter, E G, additional, Lauzière, K, additional, Ijewliw, O, additional, Bilot, I, additional, Hunt, P, additional, English, M L R, additional, Olejarz, A D, additional, Laudadio, A B, additional, Enright, A, additional, Robillard, K -L, additional, and Corriveau, L, additional

Published
2016
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42. Early Results from the Wisconsin H-Alpha Mapper Southern Sky Survey

Author

Haffner, L. M., Reynolds, R. J., Madsen, G. J., Hill, A. S., Barger, K. A., Jaehnig, K. P., Mierkiewicz, E. J., Percival, J. W., and Chopra, N.

Subjects
Astrophysics - Galaxy Astrophysics
Abstract

After a successful eleven-year campaign at Kitt Peak, we moved the Wisconsin H-Alpha Mapper (WHAM) to Cerro Tololo in early 2009. Here we present some of the early data after a few months under southern skies. These maps begin to complete the first all-sky, kinematic survey of the diffuse H-alpha emission from the Milky Way. Much of this emission arises from the Warm Ionized Medium (WIM), a significant component of the ISM that extends a few kiloparsecs above the Galactic disk. While this first look at the data focuses on the H-alpha survey, WHAM is also capable of observing many other optical emission lines, revealing fascinating trends in the temperature and ionization state of the WIM. Our ongoing studies of the physical conditions of diffuse ionized gas will continue from the southern hemisphere following the H-alpha survey. In addition, future observations will cover the full velocity range of the Magellanic Stream, Bridge, and Clouds to trace the ionized gas associated with these neighboring systems., Comment: 4 pages, 2 figures. To appear in "The Dynamic ISM: A celebration of the Canadian Galactic Plane Survey," ASP Conference Series

Published
2010

46. SDSS J160043.6+074802.9: a very rapid sdO pulsator

Author

Woudt, P. A., Kilkenny, D., Zietsman, E., Warner, B., Loaring, N. S., Copley, C., Kniazev, A., Vaisanen, P., Still, M., Stobie, R. S., Burgh, E. B., Nordsieck, K. H., Percival, J. W., O'Donoghue, D., and Buckley, D. A. H.

Subjects
Astrophysics
Abstract

We report the serendipitous discovery of the Sloan Digital Sky Survey star, SDSS J160043.6+074802.9 to be a very rapid pulsator. The variation is dominated by a frequency near 8380 microHz (period = 119.33 s) with a large amplitude (0.04 mag) and its first harmonic at 16760 microHz (59.66 s; 0.005 mag). In between these frequencies, we find at least another 8 variations with periods between 62 and 118 seconds and amplitudes between about 0.007 and 0.003 mag; weaker oscillations might also be present. Preliminary spectrograms from the performance verification phase of the Southern African Large Telescope indicate that SDSS J160043.6+074802.9 is a spectroscopic binary consisting of an sdO star and a late-type main-sequence companion. This makes it the first unambiguous detection of such an sdO star to pulsate, and certainly the first found to exhibit multi-frequency variations., Comment: 7 pages, 6 figures (figure 4 at reduced resolution, original available on request). Accepted for publication in MNRAS

Published
2006
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47. Report of activities for the geology and mineral potential of the Chantrey-Thelon area: GEM-2 Thelon tectonic zone, Montresor belt and Elu basin projects

Author

Berman, R G, primary, Davis, W J, additional, Whalen, JB, additional, McCurdy, M W, additional, Craven, J A, additional, Roberts, B J, additional, McMartin, I, additional, Percival, J A, additional, Rainbird, R H, additional, Ielpi, A, additional, Mitchell, R, additional, Sanborn-Barrie, M, additional, Nadeau, L, additional, Girard, É, additional, Carr, S, additional, and Pehrsson, S J, additional

Published
2015
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49. Geo-Mapping Frontiers' Chantrey project: bedrock geology and multidisciplinary supporting data of a 550 kilometre transect across the Thelon tectonic zone, Queen Maud block, and adjacent Rae craton

Author

Berman, R G, primary, Nadeau, L, additional, Percival, J A, additional, Harris, J, additional, Girard, É, additional, Whalen, J B, additional, Davis, W J, additional, Kellett, D, additional, Jefferson, C W, additional, Camacho, A, additional, and Bethune, K, additional

Published
2015
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