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J/AJ/153/93              MOST photometry of Proxima             (Kipping+, 2017)

No conclusive evidence for transits of Proxima b in MOST photometry. Kipping D.M., Cameron C., Hartman J.D., Davenport J.R.A., Matthews J.M., Sasselov D., Rowe J., Siverd R.J., Chen J., Sandford E., Bakos G.A., Jordan A., Bayliss D., Henning T., Mancini L., Penev K., Csubry Z., Bhatti W., Da Silva Bento J., Guenther D.B., Kuschnig R., Moffat A.F.J., Rucinski S.M., Weiss W.W. <Astron. J., 153, 93-93 (2017)> =2017AJ....153...93K (SIMBAD/NED BibCode)
ADC_Keywords: Planets ; Stars, double and multiple ; Photometry Keywords: planetary systems - stars: individual: Proxima Cen - techniques: photometric Abstract: The analysis of Proxima Centauri's radial velocities recently led Anglada-Escude et al. to claim the presence of a low-mass planet orbiting the Sun's nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%-40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1σ-2σ), leading us to argue that the signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star. Description: Microwave and Oscillations of STars (MOST) telescope is a 53kg satellite in low Earth orbit with a 15cm aperture visible band camera (35-750nm). MOST observed Proxima Centauri in 2014 May (beginning on HJD(2000) 2456793.18) for about 12.5 days. MOST again observed Proxima Centauri in 2015 May (starting on HJD(2000) 2457148.54), this time for a total of 31 days. Independent of the MOST observations, Proxima Cen was also monitored by the HATSouth ground-based telescope network. The network consists of six wide-field photometric instruments located at three observatories in the Southern Hemisphere (Las Campanas Observatory [LCO] in Chile, the High Energy Stereoscopic System [HESS] site in Namibia, and Siding Spring Observatory [SSO] in Australia), with two instruments per site. Each instrument consists of four 18cm diameter astrographs and associated 4K*4K backside-illuminated CCD cameras and Sloan r-band filters, placed on a common robotic mount. The four astrographs and cameras together cover a 8.2°*8.2° mosaic field of view at a pixel scale of 3.7''/pixel. Observations of a field containing Proxima Cen were collected as part of the general HATSouth transit survey, with a total of 11071 (this number does not count observations that were rejected as not useful for high-precision photometry, or those that produced large-amplitude outliers in the Proxima Cen light curve) composite 3*80s exposures gathered between 2012 June 14 and 2014 September 20. These include 3430 observations made with the HS-2 unit at LCO, 4630 observations made with the HS-4 unit at the HESS site, and 3011 observations made with the HS-6 unit at the SSO site. Due to weather and other factors, the cadence was nonuniform. The median time difference between consecutive observations in the full time series is 368s. Objects: ------------------------------------------------------------ RA (ICRS) DE Designation(s) ------------------------------------------------------------ 14 29 42.95 -62 40 46.2 Proxima = V* V645 Cen ------------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 41 13934 Reduced Microwave and Oscillations of STars (MOST) photometry used in this work, excluding times afflicted by large flares table5.dat 28 11071 *Reduced HATSouth photometry used in this work
Note on table5.dat: After correction for systematic trends by Trend Filtering Algorithm (TFA).
See also: J/AJ/145/5 : Follow-up photometry of HATS-1 (Penev+, 2013) J/ApJ/772/L2 : Keck/HIRES radial velocities for HD 97658 (Dragomir+, 2013) J/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011) J/ApJ/710/1724 : Follow-up photometry for HAT-P-11 (Bakos+, 2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 20 F20.15 d HJD [5248.1/5634.5] Heliocentric Julian Date of observation with correction for UTC (HJD-2451545) 22- 31 F10.7 mag Dmag [-0.039/0.042] Differential MOST magnitude 33- 41 F9.7 mag e_Dmag [0.005/0.015] uncertainty in Dmag
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 12 F12.7 d HJD [4547.6/5376.5] Heliocentric Julian Date of observation with correction for UTC (HJD-2451545) 14- 20 F7.5 mag mag [7.12/7.32] Trend Filtering Algorithm (TFA) corrected HATSouth magnitude (1) 22- 28 F7.5 mag e_mag [0.00125/0.005] Uncertainty in mag
Note (1): The data were reduced to trend-filtered light curves using the aperture photometry pipeline described by Penev et al. 2013 (Cat. J/AJ/145/5) and making use of the External Parameter Decorrelation (EPD) procedure described by Bakos et al. 2010 (Cat. J/ApJ/710/1724) and the Trend Filtering Algorithm (TFA) from Kovacs et al. 2005MNRAS.356..557K. See Section 6.1 for more details.
History: From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 27-Jun-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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