J/ApJ/812/136 OGLE-2013-BLG-446 photometry (Bachelet+, 2015)
Red noise versus planetary interpretations in the microlensing event Ogle-2013-BLG-446. Bachelet E., Bramich D.M., Han C., Greenhill J., Street R.A., Gould A., D'ago G., Alsubai K., Dominik M., Jaimes R.F., Horne K., Hundertmark M., Kains N., Snodgrass C., Steele I.A., Tsapras Y., (the Robonet collaboration), Albrow M.D., Batista V., Beaulieu J.-P., Bennett D.P., Brillant S., Caldwell J.A.R., Cassan A., Cole A., Coutures C., Dieters S., Dominis Prester D., Donatowicz J., Fouque P., Hill K., Marquette J.-B., Menzies J., Pere C., Ranc C., Wambsganss J., Warren D., (the Planet collaboration), Andrade De Almeida L., Choi J.-Y., Depoy D.L., Dong S., Hung L.-W., Hwang K.-H., Jablonski F., Jung Y.K., Kaspi S., Klein N., Lee C.-U., Maoz D., Munoz J.A., Nataf D., Park H., Pogge R.W., Polishook D., Shin I.-G., Shporer A., Yee J.C., (the µfun collaboration), Abe F., Bhattacharya A., Bond I.A., Botzler C.S., Freeman M., Fukui A., Itow Y., Koshimoto N., Ling C.H., Masuda K., Matsubara Y., Muraki Y., Ohnishi K., Philpott L.C., Rattenbury N., Saito TO., Sullivan D.J., Sumi T., Suzuki D., Tristram P.J., Yonehara A., (the Moa collaboration), Bozza V., Calchi Novati S., Ciceri S., Galianni P., Gu S.-H., Harpsoe K., Hinse T.C., Jorgensen U.G., Juncher D., Korhonen H., Mancini L., Melchiorre C., Popovas A., Postiglione A., Rabus M., Rahvar S., Schmidt R.W., Scarpetta G., Skottfelt J., Southworth J., Stabile A., Surdej J., Wang X.-B., Wertz O., (the Mindstep collaboration) <Astrophys. J., 812, 136 (2015)> =2015ApJ...812..136B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry Keywords: gravitational lensing: micro - planetary systems - techniques: photometric Abstract: For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (Amax∼3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (∼3M⊕) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account. Description: Microlensing event OGLE-2013-BLG-0446 (RA=18:06:56.18, DE=-31:39:27.2 (J2000.0); l=0.049°, b=-5.344°) was discovered on 2013 April 6 by the Optical Gravitational Lens Experiment (OGLE) Early Warning System (Udalski, 2003AcA....53..291U) and later alerted by the Microlensing Observations in Astrophysics (MOA) (Bond et al., 2001MNRAS.327..868B). Observations obtained on the rising part of the light curve indicated that this event could be highly magnified and might therefore be highly sensitive to planets (Griest & Safizadeh, 1998ApJ...500...37G; Gould et al., 2009, arXiv:0910.1832; Yee et al., 2009ApJ...703.2082Y). Follow-up teams, such as µFUN (Gould et al., 2006ApJ...644L..37G), PLANET (Beaulieu et al., 2006Natur.439..437B), RoboNet (Tsapras et al., 2009AN....330....4T), and MiNDSTEp (Dominik et al., 2008AN....329..248D), then began observations a few days before the peak of the event. The peak magnification was ∼3000 and the peak was densely sampled from different observatories. The various teams used difference image analysis (DIA) to obtain photometry: µFUN used pySIS (Albrow et al., 2009MNRAS.397.2099A), with the exception of the Auckland data, which were re-reduced using DanDIA (Bramich, 2008MNRAS.386L..77B; Bramich et al., 2013MNRAS.428.2275B). DanDIA was also used to reduce the RoboNet and the Danish data sets. PLANET data were reduced online with the WISIS pipeline, and final data sets were prepared using pySIS.61 OGLE (Udalski & Szymanski, 2015AcA....65....1U) and MOA (Bond et al., 2001MNRAS.327..868B) used their own DIA code to reduce their frames. All other data sets were reduced using pySIS. A total of 2955 data points from 16 telescopes were used for our analysis, after problematic data points were masked. Objects: ---------------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------------- 18 06 56.18 -31 39 27.2 OGLE-2013-BLG-446 = EWS 2013-BLG-446 ---------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file photom.dat 42 2955 *Raw photometry
Note on photom.dat: Data provided are "raw", meaning before error bar rescaling and systematics corrections (see the publication for more details).
Byte-by-byte Description of file: photom.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Tel Telescope and filter (TEL_FILT) (1) 12- 17 A6 --- Filt Filter (2) 19- 28 F10.5 d HJD Heliocentric Julian date (HJD-2450000) 30- 35 F6.3 mag mag Magnitude in Filter (3) 37- 42 F6.3 mag e_mag rms uncertainty on mag (3)
Note (1): List of Telescope and filter: Auckland_R, CPTA_i, CTIO_I and CTIO_V, Canopus_I, Danish_z, LSCA_i and LSCB_i, MOA_Red, OGLE_I and OGLE_V, Possum_N, SAAO_I, Salerno_I, Turitea_R, Weizmann_I Note (2): List of filter names: I = I-band CTIO, Canopus, OGLE, SAAO, Salerno and Weizmann V = V-band CTIO, OGLE N = N-band Possum R = R-band Turitea Red = Red-band MOA i+z = i+z-band Danish SDSS-i = i-band CPTA, LSCA and LSCB Note (3): The magnitude reported are instrumental, only OGLE photometry is calibrated (please consult OGLE publications for more details). Errors on magnitude below 0.001 were artificially set to 0.001.
Acknowledgements: Etienne Bachelet, etibachelet(at)gmail.com
(End) Patricia Vannier [CDS] 17-Dec-2015
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