Volume 627, July 2019
|Number of page(s)||10|
|Section||Numerical methods and codes|
|Published online||02 July 2019|
Photometry of K2 Campaign 9 bulge data
Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA
2 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
3 Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 NASA Ames Research Center, Moffett Blvd, Mountain View, CA 94035, USA
5 Bay Area Environmental Research Institute, 625 2nd St., Ste. 209, Petaluma, CA 94952, USA
6 Korea Astronomy and Space Science Institute, 776 Daedukdae-ro Yuseong-gu, Daejeon 34055, Korea
7 Max-Planck-Institute for Astronomy, Köigstuhl 17, 69117 Heidelberg, Germany
Accepted: 13 May 2019
In its Campaign 9, K2 observed dense regions toward the Galactic bulge in order to constrain the microlensing parallaxes and probe for free-floating planets. Photometric reduction of the K2 bulge data poses a significant challenge due to a combination of the very high stellar density, large pixels of the Kepler camera, and the pointing drift of the spacecraft. Here we present a new method to extract K2 photometry in dense stellar regions. We extended the Causal Pixel Model developed for less-crowded fields, first by using the pixel response function together with accurate astrometric grids, second by combining signals from a few pixels, and third by simultaneously fitting for an astrophysical model. We tested the method on two microlensing events and a long-period eclipsing binary. The extracted K2 photometry is an order of magnitude more precise than the photometry from other method.
Key words: gravitational lensing: micro / methods: observational / techniques: photometric
© ESO 2019
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