NOAO >   Observing Info >   Approved Programs >   2014A-0399

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Proposal Information for 2014A-0399


PI: Christopher Johnson, Louisiana State University, cjoh285@lsu.edu
Address: Physics Department, 202 Nicholson Hall, Tower Drive, Baton rouge, Louisiana 70810, USA

CoI: Robert Hynes, Louisiana State University
CoI: Christopher Britt, Texas Tech University
CoI: Peter Jonker, SRON, Netherlands Institute for Space Research
CoI: Tom Maccarone, Texas Tech University
CoI: Manuel Torres, SRON, Netherlands Institute for Space Research
CoI: Danny Steeghs, Warwick University
CoI: Gijs Nelemans, Radbound University

Title: Completing the DECam View of the Galactic Bulge Survey

Abstract: The Chandra Galactic Bulge Survey (GBS) has identified 1640 unique X- ray sources in the Galactic bulge above and below the plane. Most sources have one-arcsecond localizations and candidate optical counterparts, many of which are already known to be variable. We expect many of these variables to be compact binaries: low-mass X-ray binaries or cataclysmic variables, often with periods shorter than a day. The existing partial coverage variability survey of the GBS, performed with Mosaic-2, identifies many sources as variables with no clear period, but is limited by a typical sampling of 2-3 observations per night, enforced by the relatively small field of Mosaic-2. With DECam we can increase the sampling to ~28 observations per night per source, dramatically improving our sensitivity to short period binaries. Two nights of DECam coverage for the southern half of the GBS have already been obtained as Chandra Joint Time. The data acquired already demonstrates a vast improvement on the detectability of short-period variables compared to the Mosaic-2 data. We here request an additional two nights to obtain comparable coverage of the northern strip resulting in complete, homogenous DECam dataset of all GBS sources.


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