The K2 Bright Star Survey I: Methodology and Data Release. (arXiv:1908.06981v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pope_B/0/1/0/all/0/1">Benjamin J. S. Pope</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+White_T/0/1/0/all/0/1">Timothy R. White</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Farr_W/0/1/0/all/0/1">Will M. Farr</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yu_J/0/1/0/all/0/1">Jie Yu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Greklek_McKeon_M/0/1/0/all/0/1">Michael Greklek-McKeon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huber_D/0/1/0/all/0/1">Daniel Huber</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aerts_C/0/1/0/all/0/1">Conny Aerts</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aigrain_S/0/1/0/all/0/1">Suzanne Aigrain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bedding_T/0/1/0/all/0/1">Timothy R. Bedding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boyajian_T/0/1/0/all/0/1">Tabetha Boyajian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Creevey_O/0/1/0/all/0/1">Orlagh L. Creevey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hogg_D/0/1/0/all/0/1">David W. Hogg</a>
While the Kepler Mission was designed to look at tens of thousands of faint
stars (V > 12), brighter stars that saturated the detector are important
because they can be and have been observed very accurately by other
instruments. By analyzing the unsaturated scattered-light `halo’ around these
stars, we have retrieved precise light curves of most of the brightest stars in
K2 fields from Campaign~4 onwards. The halo method does not depend on the
detailed cause and form of systematics, and we show that it is effective at
extracting light curves from both normal and saturated stars. The key
methodology is to optimize the weights of a linear combination of pixel time
series with respect to an objective function. We test a range of such objective
functions, finding that lagged Total Variation, a generalization of Total
Variation, performs well on both saturated and unsaturated K2 targets. Applying
this to the bright stars across the K2 Campaigns reveals stellar variability
ubiquitously, including effects of stellar pulsation, rotation, and binarity.
We describe our pipeline and present a catalogue of the 161 bright stars, with
classifications of their variability, asteroseismic parameters for red giants
with well-measured solar-like oscillations, and remarks on interesting objects.
These light curves are publicly available as a High Level Science Product from
the Mikulski Archive for Space Telescopes (MAST).
While the Kepler Mission was designed to look at tens of thousands of faint
stars (V > 12), brighter stars that saturated the detector are important
because they can be and have been observed very accurately by other
instruments. By analyzing the unsaturated scattered-light `halo’ around these
stars, we have retrieved precise light curves of most of the brightest stars in
K2 fields from Campaign~4 onwards. The halo method does not depend on the
detailed cause and form of systematics, and we show that it is effective at
extracting light curves from both normal and saturated stars. The key
methodology is to optimize the weights of a linear combination of pixel time
series with respect to an objective function. We test a range of such objective
functions, finding that lagged Total Variation, a generalization of Total
Variation, performs well on both saturated and unsaturated K2 targets. Applying
this to the bright stars across the K2 Campaigns reveals stellar variability
ubiquitously, including effects of stellar pulsation, rotation, and binarity.
We describe our pipeline and present a catalogue of the 161 bright stars, with
classifications of their variability, asteroseismic parameters for red giants
with well-measured solar-like oscillations, and remarks on interesting objects.
These light curves are publicly available as a High Level Science Product from
the Mikulski Archive for Space Telescopes (MAST).
http://arxiv.org/icons/sfx.gif
