J/other/ExA/51.109 Transit KELT-11b observed by CHEOPS (Benz+, 2021)
The CHEOPS mission.
Benz W., Benz W., Broeg C., Fortier A., Rando N., Beck T., Beck M.,
Queloz D., Ehrenreich D., Maxted P.F.L., Isaak K.G., Billot N., Alibert Y.,
Alonso R., Antonio C., Asquier J., Bandy T., Barczy T., Barrado D.,
Barros S.C.C., Baumjohann W. Bekkelien A., Bergomi M., Biondi F.,
Bonfils X., Borsato L., Brandeker A., Busch M.-D., Cabrera J., Cessa V.,
Charnoz S., Chazelas B., Collier Cameron A., Corral Van Damme C.,
Cortes D., Davies M. B., Deleuil M., Deline A., Delrez L., Demangeon O.,
Demory B. O., Erikson A., Farinato J., Fossati L., Fridlund M., Futyan D.,
Gandolfi D., Garcia Munoz A., Gillon M., Guterman P., Gutierrez A.,
Hasiba J., Heng K., Hernandez E., Hoyer S., Kiss L.L., Kovacs Z.,
Kuntzer T., Laskar J., Lecavelier des Etangs A., Lendl M., Lopez A.,
Lora I., Lovis C., Lueftinger T., Magrin D., Malvasio L., Marafatto L.,
Michaelis H., de Miguel D., Modrego D., Munari M., Nascimbeni V.,
Olofsson G., Ottacher H., Ottensamer R., Pagano I., Palacios R., Palle E.,
Peter G., Piazza D., Piotto G., Pizarro A., Pollaco D., Ragazzoni R.,
Ratti F., Rauer H., Ribas I., Rieder M., Rohlfs R., Safa F., Salatti M.,
Santos N. C., Scandariato G., Segransan D., Simon A.E., Smith A.M.S.,
Sordet M., Sousa S. G., Steller M., Szabo G.M., Szoke J., Thomas N.,
Tschentscher M., Udry S., Van Grootel V., Viotto V., Walter I., Walton N.A.,
Wildi F., Wolter D.
<Exp. Astron., 51, 109-151 (2021)>
=2021ExA....51..109B 2021ExA....51..109B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry
Keywords: exoplanets - CHEOPS - small mission -
high-precision transit photometry
Abstract:
The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on
October 19, 2012, as the first small mission (S-mission) in the ESA
Science Programme and successfully launched on December 18, 2019, as a
secondary passenger on a Soyuz-Fregat rocket from Kourou, French
Guiana. CHEOPS is a partnership between ESA and Switzerland with
important contributions by ten additional ESA Member States. CHEOPS is
the first mission dedicated to search for transits of exoplanets using
ultrahigh precision photometry on bright stars already known to host
planets. As a follow-up mission, CHEOPS is mainly dedicated to
improving, whenever possible, existing radii measurements or provide
first accurate measurements for a subset of those planets for which
the mass has already been estimated from ground-based spectroscopic
surveys. The expected photometric precision will also allow CHEOPS to
go beyond measuring only transits and to follow phase curves or to
search for exo-moons, for example. Finally, by unveiling transiting
exoplanets with high potential for in-depth characterisation, CHEOPS
will also provide prime targets for future instruments suited to the
spectroscopic characterisation of exoplanetary atmospheres. To reach
its science objectives, requirements on the photometric precision and
stability have been derived for stars with magnitudes ranging from 6
to 12 in the V band. In particular, CHEOPS shall be able to detect
Earth-size planets transiting G5 dwarf stars (stellar radius of
0.9Rsun) in the magnitude range 6<V<9 by achieving a photometric
precision of 20 ppm in 6 hours of integration time. In the case of
K-type stars (stellar radius of 0.7R☉) of magnitude in the range
9<V<12, CHEOPS shall be able to detect transiting Neptune-size
planets achieving a photometric precision of 85ppm in 3 hours of
integration time. This precision has to be maintained over continuous
periods of observation for up to 48 hours. This precision and
stability will be achieved by using a single, frame-transfer,
back-illuminated CCD detector at the focal plane assembly of a 33.5cm
diameter, on-axis Ritchey-Chretien telescope. The nearly 275kg
spacecraft is nadir-locked, with a pointing accuracy of about 1arcsec
rms, and will allow for at least 1Gbit/day downlink. The
sun-synchronous dusk-dawn orbit at 700km altitude enables having the
Sun permanently on the backside of the spacecraft thus minimising
Earth stray light. A mission duration of 3.5 years in orbit is
foreseen to enable the execution of the science programme. During this
period, 20% of the observing time is available to the wider community
through yearly ESA call for proposals, as well as through
discretionary time approved by ESA's Director of Science. At the
time of this writing, CHEOPS commissioning has been completed and
CHEOPS has been shown to fulfill all its requirements. The mission has
now started the execution of its science programme.
Description:
During IOC-D a few stars known to host planets were targeted by CHEOPS
as part of the end-to-end validation of the operational process. The
giant planet KELT-11b was among these targets.
The observed data comprise 1500 flux measurements in a photometric
aperture with a radius of 29 arcsec from images with exposure times of
30s covering the transit of KELT-11 b on 2020-03-09. We excluded 8
exposures that provided discrepant flux measurements and 101 exposures
observed in a narrow range of spacecraft roll angle for which there is
excess scatter in the flux (∼200ppm) caused by scattered moonlight.
Objects:
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RA (2000) DE Designation(s)
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10 46 49.74 -09 23 56.5 KELT-11 = HD 93396
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
lc.dat 69 1399 Transit KELT-11b observed by CHEOPS
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See also:
J/AJ/153/215 : Photometry and spectroscopy of KELT-11 (Pepper+, 2017)
Byte-by-byte Description of file: lc.dat
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Bytes Format Units Label Explanations
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3- 16 F14.6 d BJD [2458918.12/2458918.71] Barycentric Julian
Date (TDB) (BJD-2450000)
18- 27 F10.8 --- Flux [0.99/1.01] Normalized Flux
29- 38 F10.8 --- e_Flux [0.0/0.01] Normalized Flux error
41- 47 F7.3 deg RollAngle [0.15/359.35] Spacecraft roll angle
49- 58 F10.8 --- contam [0.0/0.01] Aperture Flux contamination
60- 69 F10.8 --- Fluxdetrend [0.99/1.01] Detrended Normalized Flux
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Acknowledgements:
Monika Lendl, monika.lendl(at)unige.ch
(End) Patricia Vannier [CDS] 16-Jun-2021