Multisite campaign on the open cluster M67 – I. Observations and photometric reductions |
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| Authors: | D Stello T Arentoft T R Bedding M Y Bouzid H Bruntt Z Csubry T H Dall Z E Dind S Frandsen R L Gilliland A P Jacob H R Jensen Y B Kang S-L Kim L L Kiss H Kjeldsen J-R Koo J-A Lee C-U Lee J Nuspl C Sterken R Szabó |
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| Institution: | Institut for Fysik og Astronomi (IFA), Aarhus Universitet, 8000 Aarhus, Denmark;School of Physics, University of Sydney, NSW 2006, Australia;Department of Physics, US Air Force Academy, Colorado Springs, CO 80840, USA;Danish Asteroseismology Centre, Aarhus Universitet, DK-8000 Aarhus, Denmark;Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium;Konkoly Observatory of the Hungarian Academy of Sciences, 1525 Budapest, PO Box 67, Hungary;European Southern Observatory, Casilla 19001, Santiago 19, Chile;Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, USA;Korea Astronomy and Space Science Institute, Daejeon 305-348, Korea |
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| Abstract: | We report on an ambitious multisite campaign aimed at detecting stellar variability, particularly solar-like oscillations, in the red giant stars in the open cluster M67 (NGC 2682). During the six-week observing run, which comprised 164 telescope nights, we used nine 0.6-m to 2.1-m class telescopes located around the world to obtain uninterrupted time series photometry. We outline here the data acquisition and reduction, with emphasis on the optimization of the signal-to-noise ratio of the low-amplitude (50–500 μmag) solar-like oscillations. This includes a new and efficient method for obtaining the linearity profile of the CCD response at ultrahigh precision (∼10 parts per million). The noise in the final time series is 0.50 mmag per minute integration for the best site, while the noise in the Fourier spectrum of all sites combined is 20 μmag. In addition to the red giant stars, this data set proves to be very valuable for studying high-amplitude variable stars such as eclipsing binaries, W UMa systems and δ Scuti stars. |
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| Keywords: | techniques: photometric blue stragglers stars: oscillations δ Scuti stars: variables: other open clusters and associations: individual: M67 (NGC 2682) |
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