J/AJ/159/187 First RVs with the EXPRES spectrograph: 51Peg (Petersburg+, 2020)
An EXtreme-PREcision radial-velocity pipeline: first radial velocities from
EXPRES.
Petersburg R.R., Joel Ong J.M., Zhao L.L., Blackman R.T., Brewer J.M.,
Buchhave L.A., Cabot S.H.C., Davis A.B., Jurgenson C.A., Leet C.,
McCracken T.M., Sawyer D., Sharov M., Tronsgaard R., Szymkowiak A.E.,
Fischer D.A.
<Astron. J., 159, 187 (2020)>
=2020AJ....159..187P 2020AJ....159..187P
ADC_Keywords: Stars, double and multiple; Radial velocities; Spectra, optical
Keywords: High-resolution spectroscopy ; Radial velocity ;
Astronomy data analysis ; Observational astronomy
Abstract:
The EXtreme-PREcision Spectrograph (EXPRES) is an environmentally
stabilized, fiber-fed, R=137500, optical spectrograph. It was recently
commissioned at the 4.3m Lowell Discovery Telescope near Flagstaff,
Arizona. The spectrograph was designed with a target radial-velocity
(RV) precision of 30cm/s. In addition to instrumental innovations, the
EXPRES pipeline, presented here, is the first on-sky, optical,
fiber-fed spectrograph to employ many novel techniques-including an
"extended flat" fiber used for wavelength-dependent quantum efficiency
characterization of the CCD, a flat-relative optimal extraction
algorithm, chromatic barycentric corrections, chromatic calibration
offsets, and an ultra-precise laser frequency comb for wavelength
calibration. We describe the reduction, calibration, and RV analysis
pipeline used for EXPRES and present an example of our current
sub-meter-per-second RV measurement precision, which reaches a formal,
single-measurement error of 0.3m/s for an observation with a per-pixel
signal-to-noise ratio of 250. These velocities yield an orbital
solution on the known exoplanet host 51Peg that matches literature
values with a residual rms of 0.895m/s.
Description:
The EXtreme-PREcision Spectrograph (EXPRES) is a fiber-fed,
white-pupil Extrem Precision Radial Velocity (EPRV) spectrograph with
a design resolution of R=150000 and a wavelength range of
3800-7800Å. In practice the median resolution is better
characterized as R∼137500 with a maximum resolution reaching R∼150000
in some regions of the detector. EXPRES is environmentally stabilized
in a vacuum enclosure and is situated at Lowell Observatory's 4.3m
Lowell Discovery Telescope (LDT) near Flagstaff, Arizona.
See Section 2 for the detailed description of this instrument.
Velocities derived with the EXPRES pipeline (see Section 3) based on
47 observations of HD 217014 (51 Peg) over the 10-month span between
the beginning of Epoch 4 and December 1, 2019 are presented in Table 3.
Objects:
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RA (2000) DE Designation(s) Per
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22 57 27.98 +20 46 07.8 51 peg = WDS J22575+2046AB (P=4.2308)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 61 47 EXPRES commissioning radial velocities of 51 Peg
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See also:
III/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991)
III/244 : Catalog of Stellar Rotational Velocities (Glebocki+ 2005)
J/ApJ/616/562 : Rotational velocities in binaries (Abt+, 2004)
J/A+A/414/351 : ELODIE survey for northern exoplanets III (Naef+, 2004)
J/A+A/480/91 : Gal. disk stars vertical distribution. IV. (Soubiran+, 2008)
J/A+A/521/A12 : Radial velocities of nearby late-type stars (Maldonado+, 2010)
J/ApJ/708/1366 : Radial velocities for 61 Vir (Vogt+, 2010)
J/ApJ/723/954 : HIRES radial velocities of GJ 581 (Vogt+, 2010)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/ApJ/736/87 : Abundances in G-type stars with exoplanets (Kang+, 2011)
J/ApJ/747/108 : Rigel. I. MOST photometry and RV monitoring (Moravveji+, 2012)
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
J/ApJ/764/78 : Oxygen abundances in nearby FGK stars (Ramirez+, 2013)
J/ApJ/788/81 : BANYAN III. RVel and rotation of low-mass stars (Malo+, 2014)
J/ApJ/795/41 : HD 128311 radial velocity & astrometric data (McArthur+, 2014)
J/ApJ/806/60 : Radial velocities of 70 Vir (HD117176) (Kane+, 2015)
J/ApJ/821/89 : 12yrs of radial velocity obs. of exoplanets (Bryan+, 2016)
J/A+A/576/A134 : Radial velocities of 51 Peg (Martins+, 2015)
J/AJ/153/138 : Radial velocity curve of 51 Peg (Birkby+, 2017)
J/MNRAS/484/L8 : Correcting HIRES/Keck RVs for systematic errors (Tal-Or+,2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 18 F18.12 d MJD [58639.4/58804.1] Barycentric
Modified Julian date
20- 31 F12.3 cm/s RVelCCF [-3331563/-3320255] Cross-correlation
barycentric radial velocity
33- 38 F6.3 cm/s e_RVelCCF [20/49] Error on RVelCCF
40- 48 F9.3 cm/s RVelFM [-5178/6106] Forward model barycentric radial
velocity
50- 55 F6.3 cm/s e_RVelFM [29/46] Error on RVelFM
57- 57 I1 --- Epoch [4/5] RV calibration epoch
59- 61 I3 /pix S/N [163/385] Signal-to-noise ratio per pixel
at 550nm
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 18-May-2020