Browsing by Author "Mahabal, Ashish A."

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    Discovery of 30,000 Periodic Variables in the Southern Sky
    (2016) Drake, Andrew J.; Djorgovski, Stanislav G.; Graham, Matthew; Catelan, Márcio; Torrealba, Gabriel; Mahabal, Ashish A.; Christensen, Eric J.; Larson, Stephen M.; McNaught, Robert; Garradd, Gordon
    We have completed a search for periodic variable stars within the 30,000 square degrees of the sky covered by the Catalina Surveys. Here we present the results from our analysis of six years of optical photometry taken by the Siding Spring Survey (SSS). This data covers 200 million sources at declinations between -20 and -75 degrees in the magnitude range 11 < V < 19. In addition to the 10,000 RR Lyrae that we previously discovered in this data, we find approximately 30,000 new periodic variable stars. These sources include, eclipsing binaries, RR Lyrae, LPVs, RSCVn stars, delta Scutis and Anomalous Cepheids.As part of our ongoing search for structure within the Galactic halo we determine the distances to each of the type-ab RR Lyrae. We discover that many of these stars appear to belong to the old stellar halo of the LMC. Our analysis suggests that the stellar halo of the LMC extends far beyond the limits previously observed....
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    Optimization of the Observing Cadence for the Rubin Observatory Legacy Survey of Space and Time: A Pioneering Process of Community-focused Experimental Design
    (2022) Bianco, Federica B.; Ivezić, Željko; Jones, R. Lynne; Graham, Melissa L.; Marshall, Phil; Saha, Abhijit; Strauss, Michael A.; Yoachim, Peter; Ribeiro, Tiago; Anguita, Timo; Bauer, A. E.; Bauer, Franz E.; Bellm, Eric C.; Blum, Robert D.; Brandt, William N.; Brough, Sarah; Catelan, Márcio; Clarkson, William I.; Connolly, Andrew J.; Gawiser, Eric; Gizis, John E.; Hložek, Renée; Kaviraj, Sugata; Liu, Charles T.; Lochner, Michelle; Mahabal, Ashish A.; Mandelbaum, Rachel; McGehee, Peregrine; Neilsen, Eric H., Jr.; Olsen, Knut A. G.; Peiris, Hiranya V.; Rhodes, Jason; Richards, Gordon T.; Ridgway, Stephen; Schwamb, Megan E.; Scolnic, Dan; Shemmer, Ohad; Slater, Colin T.; Slosar, Anže; Smartt, Stephen J.; Strader, Jay; Street, Rachel; Trilling, David E.; Verma, Aprajita; Vivas, A. K.; Wechsler, Risa H.; Willman, Beth
    Vera C. Rubin Observatory is a ground-based astronomical facility under construction, a joint project of the National Science Foundation and the U.S. Department of Energy, designed to conduct a multipurpose 10 yr optical survey of the Southern Hemisphere sky: the Legacy Survey of Space and Time. Significant flexibility in survey strategy remains within the constraints imposed by the core science goals of probing dark energy and dark matter, cataloging the solar system, exploring the transient optical sky, and mapping the Milky Way. The survey's massive data throughput will be transformational for many other astrophysics domains and Rubin's data access policy sets the stage for a huge community of potential users. To ensure that the survey science potential is maximized while serving as broad a community as possible, Rubin Observatory has involved the scientific community at large in the process of setting and refining the details of the observing strategy. The motivation, history, and decision-making process of this strategy optimization are detailed in this paper, giving context to the science-driven proposals and recommendations for the survey strategy included in this Focus Issue....
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    Periodic Variable Stars Across the Southern Sky
    (2015) Drake, Andrew J.; Graham, Matthew; Djorgovski, Stanislav G.; Catelan, Márcio; Torrealba, Gabriel; Mahabal, Ashish A.; Donalek, Ciro; Christensen, Eric J.; Larson, Stephen M.; McNaught, Robert; Garradd, Gordon
    We continue our search for periodic variables within the ~30,000 square degrees of the sky covered by the Catalina Surveys. Here we analyze six years of optical photometry taken by the Siding Spring Survey (SSS), which is sensitive to sources in the range 11 < V < 19. In all, this new analysis covers ten thousand square degrees on the sky at declinations between -20 and -75 degrees. Due to the very large number of periodic variable candidates found, we perform automated classification of the stars using multivariate kernel density estimation based on features selected from previously classified northern data. We test the accuracy of the results by visually validating a large sample of the objects. We also compare the classifications with those from other automated methods. The final SSS catalog contains tens of thousands of new periodic variable stars including eclipsing binaries, RR Lyrae, LPVs, delta Scuti's and Cepheids. By combining the newly discovered LPVs and RR Lyrae with our previous discoveries, we trace the path of the Sagittarius tidal streams system across the entire sky....