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11 results on '"David Gerdes"'

1. Photometric Survey of Neptune's Trojan Asteroids. I. The Color Distribution

Author

Larissa Markwardt, Hsing Wen Lin, David Gerdes, and Fred C. Adams

Subjects
Trojan asteroids, Neptune trojans, Multi-color photometry, CCD photometry, Astronomy, QB1-991
Abstract

In 2018, Jewitt identified the “The Trojan Color Conundrum,” namely that Neptune's Trojan asteroids (NTs) had no ultrared members, unlike the the nearby Kuiper Belt. Since then, numerous ultrared NTs have been discovered, seemingly resolving this conundrum. However, it is still unclear whether or not the Kuiper Belt has a color distribution consistent with the NT population, as would be expected if it were the source population. In this work, we present a new photometric survey of 15 out of 31 NTs. We utilized the Sloan $g^{\prime} r^{\prime} i^{\prime} z^{\prime} $ filters on the IMACS f/4 instrument, which is mounted on the 6.5 m Baade telescope. In this survey, we identify four NTs as being ultrared using a principal component analysis. This result brings the ratio of red to ultrared NTs to 7.75:1, more consistent with the corresponding trans-Neptunian object ratio of 4–11:1. We also identify three targets as being blue (nearly solar) in color. Such objects may be C-type surfaces, but we see more of these blue NTs than has been observed in the Kuiper Belt. Finally, we show that there are hints of a color-absolute magnitude (H) correlation, with larger H (smaller sized, lower albedo) tending to be more red, but more data are needed to confirm this result. The origin of such a correlation remains an open question that will be addressed by future observations of the surface composition of these targets and their rotational properties.

Published
2023
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2. Spectral variability of a sample of extreme variability quasars and implications for the Mg iibroad-line region

Author

Qian Yang, Yue Shen, Yu-Ching Chen, Xin Liu, James Annis, Santiago Avila, Emmanuel Bertin, David Brooks, Elizabeth Buckley-Geer, Aurelio Carnero Rosell, Matias Carrasco Kind, Jorge Carretero, Luiz da Costa, Shantanu Desai, H Thomas Diehl, Peter Doel, Josh Frieman, Juan Garcia-Bellido, Enrique Gaztanaga, David Gerdes, Daniel Gruen, Robert Gruendl, Julia Gschwend, Gaston Gutierrez, Devon L Hollowood, Klaus Honscheid, Ben Hoyle, David James, Elisabeth Krause, Kyler Kuehn, Christopher Lidman, Marcos Lima, Marcio Maia, Jennifer Marshall, Paul Martini, Felipe Menanteau, Ramon Miquel, Andrés Plazas Malagón, Eusebio Sanchez, Vic Scarpine, Rafe Schindler, Michael Schubnell, Santiago Serrano, Ignacio Sevilla, Mathew Smith, Marcelle Soares-Santos, Flavia Sobreira, Eric Suchyta, Molly Swanson, Gregory Tarle, Vinu Vikram, and Alistair Walker

Published
2020
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3. Acceleration of Coronal Mass Ejection Plasma in the Low Corona as Measured by the Citizen CATE Experiment

Author

Matthew J Penn, Robert Baer, Donald Walter, Michael Pierce, Richard Gelderman, Andrei Ursache, David Elmore, Adrianna Mitchell, Sarah Kovac, Honor Hare, Myles McKay, Logan Jensen, Zachary Watson, Mike Conley, Lynn Powers, Marianna Lazarova, Joseph Wright, David Young, Fred Isberner, C. Alexandra Hart, N. R. Sheeley, Debbie Penn, Kate Allen-Penn, Bruce Alder, Ryan Alder, Geri Hall-Conley, David Gerdes, Katherine Weber, Jeffrey Johnson, Gerald Matzek, Steven Somes, Rob Sobnosky, Robert McGowen, Michael Meo, Damani Proctor, Charlie Wessinger, Jeannine Schilling, Jay Kerr, Alexander Beltzer-Sweeney, Alex Falatoun, David Higgins, Grady Boyce, Jared Hettick, Philip Blanco, Scott Dixon, Sepehr Ardebilianfard, Pat Boyce, Richard Lighthill, Denese Lighthill, David Anderson, Mine Anderson, Thomas Schad, Sonna Smith, Declan Jensen, Anthony Allen, Donavan Smith, Gage Brandon, Joe Earp, Jane Earp, Bob Blair, Chuck F. Claver, Jennifer A. Claver, Ryan H. Claver, Danielle Hoops, Esteban Rivera, Llanee Gibson, Martin Hiner, Rein Lann, Shaedyn Miller, Burton Briggs, Karan Davis, Brian Jackson, Kaleb Kautzsch, Wesley Sandidge, Russell Lucas, Duane Gregg, Julia Kamenetzky, Tiffany Rivera, Joe Shaw, Bryan Scherrer, Dylan Sandbak, Richard McFate, Wilson Harris, Zachery Brasier, Stephen McNeil, Jack Jensen, Makai Jensen, Mason Moore, Alexandria Temple, Thomas Vanderhorst, Richard Kautz, Orion Bellorado, LaVor R Jenkins, Corey Pantuso, Marley Carey, Josh Byrnes, Kyle Scholtens, Julian Web, Brain Baker, Katie Barngrover, Drew Hathaway, Kallen Smith, Kellyn Chandler, Lydia Hinkle, Ione Chandler, Galen Gisler, Jack Benner, Madison Mas, Maya Rogers, Prescott Moore, Elijah Pelofske, Stephen Gulley, Beth Short, Isabel Crooker, Jennifer Hammock, Katsina Cardenas, Kateri Cardenas, Jennifer Wellman, Mark Roy, Joe Meyer, Jalynne Brough, Kameron Brough, Tim Nelson, Zack Nelson, Caleb Russell, Theresa Bautz, Eric Weitzel & Team, Michele Wistisen, Shae Aagard, Zachary Whipps, Logan Neuroth, Dawson Poste, Connor Worthen, Sanjay Gosain, Mark Steward, Vanshita Gosain, Ruchi Gosain, Janet Jorgensen, Eleanor Doucette, Reba Doucette, Elliott Iwen, Alexus Cochran, James Stith, Doug Scribner, Austen Kenney, Kolby Pisciotti, Irene Pease, Samuel Cynamon, Charles Cynamon, Dawn Cynamon, Bart Tolbert, Jean A. Dupree, Jeremy Weremeichik, Nathan Pindell, Kristen Stives, Thomas K Simacek, Yolanta G Simacek, Anne L. Simacek, Wayne Boeck, Andreea Boeck, Austin Ryan, Gabriel Wierzorec, Dimitri Klebe, Bryan Costanza, Arnie Cerny, Trevor Schmale, Tessa Hoffman, Sam Streeter, Jack Erickson, Michele McClellan, Ella Erickson, Brynn Brettell, Savannah Shoffner, Emilie McClellan, Julie VanVoorhis, Cole Bramhall, Daniel Stelly, Bentley Bee, Bruno Acevedo, Madison Kroeger, Ben Trumpenski, Nolan Sump, Liam Brook, Jagert Ernzen, Jessica Lewis, Ryan Maderak, Charles Kennedy, David Dembinski, Rita Wright, Michael Foster, Mohammad Ahmadbasir, Monty Laycox, James Foster, Ethan Orr, Ashley Staab, Angela Speck, Sean Baldridge, Lucy Kegley, Jordan Bavlnka, Thomas Ballew, Bruce Callen, Gregory Ojakangas, Mark Bremer, Maryanne Angliongto, Mark Redecker, Chris Bremer, Peggy Hill, Michael Rodgers, Jordan Duncan, Sam Fincher, Ben Nielsen, Samantha Hasler, Taylor Shivelbine, Tyler Howard, Chris Midden, Sean Patrick, Kerry Glenn, Chris Mandrell, Kyle Dawson, Margaret Cortez, Alyssa Levsky, Dinuka Gallaba, Mason Perrone, Jasmyn Taylor, Padma A. Yanamandra-Fisher, Howard Harper, Lindsay Adams, Michaela Springer, BillyJoe Menard, Dylan Boggs, Caitlin Lynch, Jacob Watson, Andi York, David Matthews, Kiley Brown, Dylan Garrison, Jonathan Mangin, Isaac Mangin, Jennifer Birriel, Ignacio Birriel, Capp Yess, Jesse Anderson, Ethan Caudill, Allyn Smith, Spencer Buckner, Russ Longhurst, Ben Fagan, Christian Nations, Jeffrey DiMatties, Patricia Thompson, David Garrison, Thomas Garrison, William Garrison, Mary Kidd, Maria Baker, Mary-Beth Ledford, Amy Winebarger, Michael Freed, Morgyn Church, Jim Dickens, Bob Anderson, Ned Smith, Lynne Dorsey, Doug Justice, Daniel Zavala, Zach Stockbridge, Sean Brittain, Stanley Jensen, Harrison Leiendecker, Erin Thompson, Michelle Deady, Kelly Quinn-Hughes, David Slimmer, Valerie Granger, Michael LaRoche, Serena Hill LaRoche, Rachel Manspeaker, Peter Nguyen, Daniel Smith, Jim Payne, Jerry Zissett, Arianna M. Roberts, Gabrielle W. Roberts, Harrison Roberts, Amy Riddle, Corina Ursache, and Elena Ursache

Published
2019
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4. A Collision Mechanism for the Removal of Earth's Trojan Asteroids

Author

Kevin Napier, Fred Adams, David Gerdes, Hsing Wen Lin, and Larissa Markwardt

Subjects
Geophysics, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Astronomy and Astrophysics
Abstract

Due to their strong resonances with their host planet, Trojan asteroids can remain in stable orbits for billions of years. As a result, they are powerful probes for constraining the dynamical and chemical history of the solar system. Although we have detected thousands of Jupiter Trojans and dozens of Neptune Trojans, there are currently no known long-term stable Earth Trojans (ETs). Dynamical simulations show that the parameter space for stable ETs is substantial, so their apparent absence poses a mystery. This work uses a large ensemble of N-body simulations to explore how the Trojan population dynamically responds if Earth suffers large collisions, such as those thought to have occurred to form the Moon and/or to have given Earth its late veneer. We show that such collisions can be highly disruptive to the primordial Trojan population, and could have eliminated it altogether. More specifically, if Earth acquired the final 1% of its mass through  ( 10 ) collisions, then only ∼1% of the previously bound Trojan population would remain.

Published
2022
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5. Long-term Stability of Six Neptunian Trojans

Author

Kevin Napier, Fred Adams, David Gerdes, Hsing Wen Lin, and Larissa Markwardt

Subjects
General Medicine
Abstract

This paper explores the long-term stability of six Neptunian Trojans. In contrast with other Neptunian Trojans, these objects have previously unknown lifetimes and larger orbital uncertainties due to their shorter observational arcs. We obtained new astrometry of the six Trojans using the Magellan telescope, refit their orbits, and performed Gyr-long numerical integrations to estimate their lifetimes. The results show that five of these six objects are stable over Gyr timescales. The remaining object, 2015 VV165, has a calculated lifetime of 0.691 ± 0.001 Gyr, which is similar to the previous estimate of 0.65 Gyr. As a result, the shorter lifetime of this latter object is most likely physical (rather than due to uncertainties in its orbital determination).

Published
2022
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7. Status of the dark energy survey camera (DECam) project

Author

Brenna L. Flaugher, Timothy M. C. Abbott, Jim Annis, Michelle L. Antonik, Jim Bailey, Otger Ballester, Joseph P. Bernstein, Rebecca Bernstein, Marco Bonati, Gale Bremer, Jorge Briones, David Brooks, Elizabeth J. Buckley-Geer, Julia Campa, Laia Cardiel-Sas, Francisco Castander, Javier Castilla, Herman Cease, Steve Chappa, Edward C. Chi, Luis da Costa, Darren L. DePoy, Gregory Derylo, Juan De Vicente, H. Thomas Diehl, Peter Doel, Juan Estrada, Jacob Eiting, Anne Elliott, David Finley, Josh Frieman, Enrique Gaztanaga, David Gerdes, Mike Gladders, V. Guarino, G. Gutierrez, Jim Grudzinski, Bill Hanlon, Jiangang Hao, Steve Holland, Klaus Honscheid, Dave Huffman, Cheryl Jackson, Inga Karliner, Daekwang Kau, Steve Kent, Kurt Krempetz, John Krider, Mark Kozlovsky, Donna Kubik, Kyler W. Kuehn, Stephen E. Kuhlmann, Kevin Kuk, Ofer Lahav, Peter Lewis, Huan Lin, Wolfgang Lorenzon, Stuart Marshall, Gustavo Martínez, Timothy McKay, Wyatt Merritt, Mark Meyer, Ramon Miquel, Jim Morgan, Peter Moore, Todd Moore, Brian Nord, R. Ogando, Jamieson Olsen, John Peoples, Andreas Plazas, Natalie Roe, Aaron Roodman, B. Rossetto, E. Sanchez, Vic Scarpine, Terry Schalk, Rafe Schindler, Ricardo Schmidt, Richard Schmitt, Mike Schubnell, Kenneth Schultz, M. Selen, S. Serrano, Terri Shaw, Vaidis Simaitis, Jean Slaughter, R. Christopher Smith, Hal Spinka, Andy Stefanik, Walter Stuermer, Adam Sypniewski, Rick Talaga, Greg Tarle, Jon Thaler, Doug Tucker, Alistair R. Walker, Curtis Weaverdyck, William Wester, Robert J. Woods, Sue Worswick, and Allen Zhao

Published
2010
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8. Users guide for seeds of western trees and shrubs

Author

Scott Wolff, Rodger Danielson, William I. Stein, David. Gerdes, and Nancy Shaw

Subjects
Engineering, Seed tree, ved/biology, business.industry, ved/biology.organism_classification_rank.species, Forestry, business, Shrub, Seed testing
Abstract

Because the role of tree and shrub seed is indispensable in the renewal of forests and ranges, their identity and quality are critically important. This guide briefly covers recommended practices for maintaining the identity of seeds, for sampling them, and for testing them for quality. Practices associated with the testing and use of tree seed have developed over many years, whereas those for shrub seed are just developing. Selected references, excerpts from official seed testing rules, addresses of seed testing laboratories, and sources of information for shrub seed are included.

Published
1986
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9. Designing an Optimal Kilonova Search using DECam for Gravitational Wave Events

Author

Clecio Bom, James Annis, Alyssa Garcia, Antonella Palmese, Nora Sherman, Marcelle Soares-Santos, Luidhy Santana-Silva, Robert Morgan, Bechtol, K., Davis, T., Diehl, H. T., Sahar Allam, Tristan Bachmann, Fraga, B. M. O., Juan Garcia-Bellido, Mandeep Gill, Kenneth Herner, Kilpatrick, C. D., Martin Makler, Felipe Olivares E., Maria Elidaiana da Silva Pereira, Pineda, J., Santos, A., Douglas Tucker, Matthew Wiesner, Aguena, M., Alves, O., Bacon, D., Bernardinelli, P. H., Bertin, E., Sebastian Bocquet, David Brooks, Matias Carrasco Kind, Carretero, J., Christopher Conselice, Costanzi, M., Da Costa, L. N., Juan De Vicente-Albendea, Shantanu Desai, Doel, P., Everett, S., Ferrero, I., Joshua Frieman, Gatti, M., David Gerdes, Daniel Gruen, Gruendl, R. A., Gaston Gutierrez, Hinton, S. R., Hollowood, D. L., Klaus Honscheid, David James, Kyler Kuehn, Nikolay Kuropatkin, Peter Melchior, Juan Mena-Fernández, Felipe Menanteau, ADRIANO PIERES, Plazas Malagón, Andrés A., Raveri, M., Rodriguez-Monroy, M., Sanchez, E., Santiago, B., Ignacio Sevilla-Noarbe, Mathew Smith, Eric Suchyta, Swanson, M. E. C., Gregory Tarlé, Chun-Hao To, and Weaverdyck, N.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), General Relativity and Quantum Cosmology
Abstract

We address the problem of optimally identifying all kilonovae detected via gravitational wave emission in the upcoming LIGO/Virgo/KAGRA Collaboration observing run, O4, which is expected to be sensitive to a factor of $\sim 7$ more Binary Neutron Stars alerts than previously. Electromagnetic follow-up of all but the brightest of these new events will require $>1$ meter telescopes, for which limited time is available. We present an optimized observing strategy for the Dark Energy Camera during O4. We base our study on simulations of gravitational wave events expected for O4 and wide-prior kilonova simulations. We derive the detectabilities of events for realistic observing conditions. We optimize our strategy for confirming a kilonova while minimizing telescope time. For a wide range of kilonova parameters, corresponding to a fainter kilonova compared to GW170817/AT2017gfo we find that, with this optimal strategy, the discovery probability for electromagnetic counterparts with the Dark Energy Camera is $\sim 80\%$ at the nominal binary neutron star gravitational wave detection limit for the next LVK observing run (190 Mpc), which corresponds to a $\sim 30\%$ improvement compared to the strategy adopted during the previous observing run. For more distant events ($\sim 330$ Mpc), we reach a $\sim 60\%$ probability of detection, a factor of $\sim 2$ increase. For a brighter kilonova model dominated by the blue component that reproduces the observations of GW170817/AT2017gfo, we find that we can reach $\sim 90\%$ probability of detection out to 330 Mpc, representing an increase of $\sim 20 \%$, while also reducing the total telescope time required to follow-up events by $\sim 20\%$., 23 pages, 10 figures, to be submitted to AAS Journals

10. Status of the Dark Energy Survey Camera (DECam) Project

Author

Brenna L. Flaugher, Timothy M. C. Abbott, Robert Angstadt, Jim Annis, Michelle L. Antonik, Jim Bailey, Otger Ballester, Joseph P. Bernstein, Rebecca A. Bernstein, Marco Bonati, Gale Bremer, Jorge Briones, David Brooks, Elizabeth J. Buckley-Geer, Juila Campa, Laia Cardiel-Sas, Francisco Castander, Javier Castilla, Herman Cease, Steve Chappa, Edward C. Chi, Luis da Costa, Darren L. DePoy, Gregory Derylo, Juan de Vincente, H. Thomas Diehl, Peter Doel, Juan Estrada, Jacob Eiting, Anne E. Elliott, David A. Finley, Rolando Flores, Josh Frieman, Enrique Gaztanaga, David Gerdes, Mike Gladders, V. Guarino, G. Gutierrez, Jim Grudzinski, Bill Hanlon, Jiangang Hao, Steve Holland, Klaus Honscheid, Dave Huffman, Cheryl Jackson, Michelle Jonas, Inga Karliner, Daekwang Kau, Steve Kent, Mark Kozlovsky, Kurt Krempetz, John Krider, Donna Kubik, Kyler Kuehn, Steve E. Kuhlmann, Kevin Kuk, Ofer Lahav, Nick Langellier, Andrew Lathrop, Peter M. Lewis, Huan Lin, Wolfgang Lorenzon, Gustavo Martinez, Timothy McKay, Wyatt Merritt, Mark Meyer, Ramon Miquel, Jim Morgan, Peter Moore, Todd Moore, Eric Neilsen, Brian Nord, Ricardo Ogando, Jamieson Olson, Kenneth Patton, John Peoples, Andres Plazas, Tao Qian, Natalie Roe, Aaron Roodman, B. Rossetto, E. Sanchez, Marcelle Soares-Santos, Vic Scarpine, Terry Schalk, Rafe Schindler, Ricardo Schmidt, Richard Schmitt, Mike Schubnell, Kenneth Schultz, M. Selen, Santiago Serrano, Terri Shaw, Vaidas Simaitis, Jean Slaughter, R. Christopher Smith, Hal Spinka, Andy Stefanik, Walter Stuermer, Adam Sypniewski, R. Talaga, Greg Tarle, Jon Thaler, Doug Tucker, Alistair R. Walker, Curtis Weaverdyck, William Wester, Robert J. Woods, Sue Worswick, and Allen Zhao

Subjects
Physics, Telescope, Ccd camera, law, Dark energy, Astronomy, Astrophysics, Square degree, law.invention
Abstract

The Dark Energy Survey Collaboration has completed construction of the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera which will be mounted on the Blanco 4-meter telescope at CTIO. DECam will be used to perform the 5000 sq. deg. Dark Energy Survey with 30% of the telescope time over a 5 year period. During the remainder of the time, and after the survey, DECam will be available as a community instrument. All components of DECam have been shipped to Chile and post-shipping checkout finished in Jan. 2012. Installation is in progress. A summary of lessons learned and an update of the performance of DECam and the status of the DECam installation and commissioning will be presented.

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