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Tim Axelrod
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Tim Axelrod
United States

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Instrumentation and Methods for Astrophysics (6)
Astrophysics (3)
Solar and Stellar Astrophysics (2)
Astrophysics of Galaxies (1)
Earth and Planetary Astrophysics (1)
Computer Science - Distributed; Parallel; and Cluster Computing (1)
High Energy Astrophysical Phenomena (1)
Cosmology and Nongalactic Astrophysics (1)

Publications Authored By Tim Axelrod

The Arizona-NOAO Temporal Analysis and Response to Events System (ANTARES) is a joint effort of NOAO and the Department of Computer Science at the University of Arizona to build prototype software to process alerts from time-domain surveys, especially LSST, to identify those alerts that must be followed up immediately. Value is added by annotating incoming alerts with existing information from previous surveys and compilations across the electromagnetic spectrum and from the history of past alerts. Comparison against a knowledge repository of properties and features of known or predicted kinds of variable phenomena is used for categorization. Read More

How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disc, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. Read More

We present initial results from a program aimed at establishing a network of hot DA white dwarfs to serve as spectrophotometric standards for present and future wide-field surveys. These stars span the equatorial zone and are faint enough to be conveniently observed throughout the year with large-aperture telescopes. Spectra of these white dwarfs are analyzed to generate a non-local-thermodynamic-equilibrium (NLTE) model atmosphere normalized to HST colors, including adjustments for wavelength-dependent interstellar extinction. Read More

The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field, ground-based survey system that will image the sky in six optical bands from 320 to 1050 nm, uniformly covering approximately $18,000$deg$^2$ of the sky over 800 times. The LSST is currently under construction on Cerro Pach\'on in Chile, and expected to enter operations in 2022. Once operational, the LSST will explore a wide range of astrophysical questions, from discovering "killer" asteroids to examining the nature of Dark Energy. Read More

The SKA will be capable of producing a stream of science data products that are Exa-scale in terms of their storage and processing requirements. This Google-scale enterprise is attracting considerable international interest and excitement from within the industrial and academic communities. In this chapter we examine the data flow, storage and processing requirements of a number of key SKA survey science projects to be executed on the baseline SKA1 configuration. Read More

The Arizona-NOAO Temporal Analysis and Response to Events System (ANTARES) is a joint project of the National Optical Astronomy Observatory and the Department of Computer Science at the University of Arizona. The goal is to build the software infrastructure necessary to process and filter alerts produced by time-domain surveys, with the ultimate source of such alerts being the Large Synoptic Survey Telescope (LSST). The ANTARES broker will add value to alerts by annotating them with information from external sources such as previous surveys from across the electromagnetic spectrum. Read More

We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining the LSST calibra- tion process and the information that will be available from Gaia, we explore two options for using Gaia data. The first is to use Gaia G-band photometry of selected stars, in conjunction with knowledge of the stellar parameters Teff, log g, and AV, and in some cases Z, to create photometric standards in the LSST u, g, r, i, z, and y bands. Read More

Authors: LSST Science Collaboration, Paul A. Abell1, Julius Allison2, Scott F. Anderson3, John R. Andrew4, J. Roger P. Angel5, Lee Armus6, David Arnett7, S. J. Asztalos8, Tim S. Axelrod9, Stephen Bailey10, D. R. Ballantyne11, Justin R. Bankert12, Wayne A. Barkhouse13, Jeffrey D. Barr14, L. Felipe Barrientos15, Aaron J. Barth16, James G. Bartlett17, Andrew C. Becker18, Jacek Becla19, Timothy C. Beers20, Joseph P. Bernstein21, Rahul Biswas22, Michael R. Blanton23, Joshua S. Bloom24, John J. Bochanski25, Pat Boeshaar26, Kirk D. Borne27, Marusa Bradac28, W. N. Brandt29, Carrie R. Bridge30, Michael E. Brown31, Robert J. Brunner32, James S. Bullock33, Adam J. Burgasser34, James H. Burge35, David L. Burke36, Phillip A. Cargile37, Srinivasan Chandrasekharan38, George Chartas39, Steven R. Chesley40, You-Hua Chu41, David Cinabro42, Mark W. Claire43, Charles F. Claver44, Douglas Clowe45, A. J. Connolly46, Kem H. Cook47, Jeff Cooke48, Asantha Cooray49, Kevin R. Covey50, Christopher S. Culliton51, Roelof de Jong52, Willem H. de Vries53, Victor P. Debattista54, Francisco Delgado55, Ian P. Dell'Antonio56, Saurav Dhital57, Rosanne Di Stefano58, Mark Dickinson59, Benjamin Dilday60, S. G. Djorgovski61, Gregory Dobler62, Ciro Donalek63, Gregory Dubois-Felsmann64, Josef Durech65, Ardis Eliasdottir66, Michael Eracleous67, Laurent Eyer68, Emilio E. Falco69, Xiaohui Fan70, Christopher D. Fassnacht71, Harry C. Ferguson72, Yanga R. Fernandez73, Brian D. Fields74, Douglas Finkbeiner75, Eduardo E. Figueroa76, Derek B. Fox77, Harold Francke78, James S. Frank79, Josh Frieman80, Sebastien Fromenteau81, Muhammad Furqan82, Gaspar Galaz83, A. Gal-Yam84, Peter Garnavich85, Eric Gawiser86, John Geary87, Perry Gee88, Robert R. Gibson89, Kirk Gilmore90, Emily A. Grace91, Richard F. Green92, William J. Gressler93, Carl J. Grillmair94, Salman Habib95, J. S. Haggerty96, Mario Hamuy97, Alan W. Harris98, Suzanne L. Hawley99, Alan F. Heavens100, Leslie Hebb101, Todd J. Henry102, Edward Hileman103, Eric J. Hilton104, Keri Hoadley105, J. B. Holberg106, Matt J. Holman107, Steve B. Howell108, Leopoldo Infante109, Zeljko Ivezic110, Suzanne H. Jacoby111, Bhuvnesh Jain112, R113, Jedicke114, M. James Jee115, J. Garrett Jernigan116, Saurabh W. Jha117, Kathryn V. Johnston118, R. Lynne Jones119, Mario Juric120, Mikko Kaasalainen121, Styliani122, Kafka, Steven M. Kahn, Nathan A. Kaib, Jason Kalirai, Jeff Kantor, Mansi M. Kasliwal, Charles R. Keeton, Richard Kessler, Zoran Knezevic, Adam Kowalski, Victor L. Krabbendam, K. Simon Krughoff, Shrinivas Kulkarni, Stephen Kuhlman, Mark Lacy, Sebastien Lepine, Ming Liang, Amy Lien, Paulina Lira, Knox S. Long, Suzanne Lorenz, Jennifer M. Lotz, R. H. Lupton, Julie Lutz, Lucas M. Macri, Ashish A. Mahabal, Rachel Mandelbaum, Phil Marshall, Morgan May, Peregrine M. McGehee, Brian T. Meadows, Alan Meert, Andrea Milani, Christopher J. Miller, Michelle Miller, David Mills, Dante Minniti, David Monet, Anjum S. Mukadam, Ehud Nakar, Douglas R. Neill, Jeffrey A. Newman, Sergei Nikolaev, Martin Nordby, Paul O'Connor, Masamune Oguri, John Oliver, Scot S. Olivier, Julia K. Olsen, Knut Olsen, Edward W. Olszewski, Hakeem Oluseyi, Nelson D. Padilla, Alex Parker, Joshua Pepper, John R. Peterson, Catherine Petry, Philip A. Pinto, James L. Pizagno, Bogdan Popescu, Andrej Prsa, Veljko Radcka, M. Jordan Raddick, Andrew Rasmussen, Arne Rau, Jeonghee Rho, James E. Rhoads, Gordon T. Richards, Stephen T. Ridgway, Brant E. Robertson, Rok Roskar, Abhijit Saha, Ata Sarajedini, Evan Scannapieco, Terry Schalk, Rafe Schindler, Samuel Schmidt, Sarah Schmidt, Donald P. Schneider, German Schumacher, Ryan Scranton, Jacques Sebag, Lynn G. Seppala, Ohad Shemmer, Joshua D. Simon, M. Sivertz, Howard A. Smith, J. Allyn Smith, Nathan Smith, Anna H. Spitz, Adam Stanford, Keivan G. Stassun, Jay Strader, Michael A. Strauss, Christopher W. Stubbs, Donald W. Sweeney, Alex Szalay, Paula Szkody, Masahiro Takada, Paul Thorman, David E. Trilling, Virginia Trimble, Anthony Tyson, Richard Van Berg, Daniel Vanden Berk, Jake VanderPlas, Licia Verde, Bojan Vrsnak, Lucianne M. Walkowicz, Benjamin D. Wandelt, Sheng Wang, Yun Wang, Michael Warner, Risa H. Wechsler, Andrew A. West, Oliver Wiecha, Benjamin F. Williams, Beth Willman, David Wittman, Sidney C. Wolff, W. Michael Wood-Vasey, Przemek Wozniak, Patrick Young, Andrew Zentner, Hu Zhan
Affiliations: 1Stella, 2Stella, 3Stella, 4Stella, 5Stella, 6Stella, 7Stella, 8Stella, 9Stella, 10Stella, 11Stella, 12Stella, 13Stella, 14Stella, 15Stella, 16Stella, 17Stella, 18Stella, 19Stella, 20Stella, 21Stella, 22Stella, 23Stella, 24Stella, 25Stella, 26Stella, 27Stella, 28Stella, 29Stella, 30Stella, 31Stella, 32Stella, 33Stella, 34Stella, 35Stella, 36Stella, 37Stella, 38Stella, 39Stella, 40Stella, 41Stella, 42Stella, 43Stella, 44Stella, 45Stella, 46Stella, 47Stella, 48Stella, 49Stella, 50Stella, 51Stella, 52Stella, 53Stella, 54Stella, 55Stella, 56Stella, 57Stella, 58Stella, 59Stella, 60Stella, 61Stella, 62Stella, 63Stella, 64Stella, 65Stella, 66Stella, 67Stella, 68Stella, 69Stella, 70Stella, 71Stella, 72Stella, 73Stella, 74Stella, 75Stella, 76Stella, 77Stella, 78Stella, 79Stella, 80Stella, 81Stella, 82Stella, 83Stella, 84Stella, 85Stella, 86Stella, 87Stella, 88Stella, 89Stella, 90Stella, 91Stella, 92Stella, 93Stella, 94Stella, 95Stella, 96Stella, 97Stella, 98Stella, 99Stella, 100Stella, 101Stella, 102Stella, 103Stella, 104Stella, 105Stella, 106Stella, 107Stella, 108Stella, 109Stella, 110Stella, 111Stella, 112Stella, 113Stella, 114Stella, 115Stella, 116Stella, 117Stella, 118Stella, 119Stella, 120Stella, 121Stella, 122Stella

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9. Read More

Affiliations: 1CfA, 2STScI, 3CfA, 4Steward Observatory, 5LLNL, 6Caltech, 7Carnegie Observatories
Category: Astrophysics

We present a measurement of the systemic proper motion of the Large Magellanic Cloud (LMC) from astrometry with the High Resolution Camera (HRC) of the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). We observed LMC fields centered on 21 background QSOs that were discovered from their optical variability in the MACHO database. The QSOs are distributed homogeneously behind the central few degrees of the LMC. Read More

The Taiwanese-American Occultation Survey (TAOS) will detect objects in the Kuiper Belt, by measuring the rate of occultations of stars by these objects, using an array of three to four 50cm wide-field robotic telescopes. Thousands of stars will be monitored, resulting in hundreds of millions of photometric measurements per night. To optimize the success of TAOS, we have investigated various methods of gathering and processing the data and developed statistical methods for detecting occultations. Read More

We have performed a search for halo white dwarfs as high proper motion objects in a second epoch WFPC2 image of the Groth-Westphal strip. We identify 24 high proper motion objects with mu > 0.014 ''/yr. Read More