The PRL stabilized high-resolution echelle fiber-fed spectrograph: Instrument description and first radial velocity results

Abhijit Chakraborty, Suvrath Mahadevan, Arpita Roy, Vaibhav Dixit, Eric Harvey Richardson, Varun Dongre, F. M. Pathan, Priyanka Chaturvedi, Vishal Shah, Girish P. Ubale, B. G. Anandarao

Research output: Contribution to journalArticle

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Abstract

We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mount Abu 1.2 m telescope in India. Data obtained as part of the postcommissioning tests with PARAS show velocity precision better than 2 m s-1 over a period of several months on bright RV standard stars. For observations of σ Dra, we report 1.7 m s-1 precision for a period of 7 months, and for HD 9407, we report 2.1 m s-1 over a period of 2 months. PARAS is capable of single-shot spectral coverage of 3800-9500 Å at a resolution of ~67,000. The RV results were obtained between 3800 and 6900 Å using simultaneous wavelength calibration with a thorium-argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01-0.02° C (rms) at 25.55° C and is enclosed in a vacuum vessel at pressure of 0.1 ± 0.03 mbar. The blaze peak efficiency of the spectrograph between 5000 and 6500 Å, including the detector, is ~30%; it is ~25% with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81% reflectivity) is ~7% in the same wavelength region on a clear night with good seeing conditions. The stable point-spread function (PSF), environmental control, existence of a simultaneous calibration fiber, and availability of observing time make PARAS attractive for a variety of exoplanetary and stellar astrophysics projects. Future plans include testing of octagonal fibers for further scrambling of light and extensive calibration over the entire wavelength range up to 9500 Å using thorium-neon (ThNe) or uranium-neon (UNe) spectral lamps. Thus, we demonstrate how such highly stabilized instruments, even on small aperture telescopes, can contribute significantly to the ongoing radial velocity searches for low-mass planets around bright stars.

Original languageEnglish (US)
Pages (from-to)133-147
Number of pages15
JournalPublications of the Astronomical Society of the Pacific
Volume126
Issue number936
DOIs
StatePublished - Feb 1 2014

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radial velocity
spectrographs
fibers
high resolution
neon
thorium
telescopes
calibration
wavelength
luminaires
wavelengths
environmental control
stars
astrophysics
hollow cathodes
point spread functions
argon
India
night
reflectivity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Chakraborty, Abhijit ; Mahadevan, Suvrath ; Roy, Arpita ; Dixit, Vaibhav ; Richardson, Eric Harvey ; Dongre, Varun ; Pathan, F. M. ; Chaturvedi, Priyanka ; Shah, Vishal ; Ubale, Girish P. ; Anandarao, B. G. / The PRL stabilized high-resolution echelle fiber-fed spectrograph : Instrument description and first radial velocity results. In: Publications of the Astronomical Society of the Pacific. 2014 ; Vol. 126, No. 936. pp. 133-147.
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abstract = "We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mount Abu 1.2 m telescope in India. Data obtained as part of the postcommissioning tests with PARAS show velocity precision better than 2 m s-1 over a period of several months on bright RV standard stars. For observations of σ Dra, we report 1.7 m s-1 precision for a period of 7 months, and for HD 9407, we report 2.1 m s-1 over a period of 2 months. PARAS is capable of single-shot spectral coverage of 3800-9500 {\AA} at a resolution of ~67,000. The RV results were obtained between 3800 and 6900 {\AA} using simultaneous wavelength calibration with a thorium-argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01-0.02° C (rms) at 25.55° C and is enclosed in a vacuum vessel at pressure of 0.1 ± 0.03 mbar. The blaze peak efficiency of the spectrograph between 5000 and 6500 {\AA}, including the detector, is ~30{\%}; it is ~25{\%} with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81{\%} reflectivity) is ~7{\%} in the same wavelength region on a clear night with good seeing conditions. The stable point-spread function (PSF), environmental control, existence of a simultaneous calibration fiber, and availability of observing time make PARAS attractive for a variety of exoplanetary and stellar astrophysics projects. Future plans include testing of octagonal fibers for further scrambling of light and extensive calibration over the entire wavelength range up to 9500 {\AA} using thorium-neon (ThNe) or uranium-neon (UNe) spectral lamps. Thus, we demonstrate how such highly stabilized instruments, even on small aperture telescopes, can contribute significantly to the ongoing radial velocity searches for low-mass planets around bright stars.",
author = "Abhijit Chakraborty and Suvrath Mahadevan and Arpita Roy and Vaibhav Dixit and Richardson, {Eric Harvey} and Varun Dongre and Pathan, {F. M.} and Priyanka Chaturvedi and Vishal Shah and Ubale, {Girish P.} and Anandarao, {B. G.}",
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Chakraborty, A, Mahadevan, S, Roy, A, Dixit, V, Richardson, EH, Dongre, V, Pathan, FM, Chaturvedi, P, Shah, V, Ubale, GP & Anandarao, BG 2014, 'The PRL stabilized high-resolution echelle fiber-fed spectrograph: Instrument description and first radial velocity results', Publications of the Astronomical Society of the Pacific, vol. 126, no. 936, pp. 133-147. https://doi.org/10.1086/675352

The PRL stabilized high-resolution echelle fiber-fed spectrograph : Instrument description and first radial velocity results. / Chakraborty, Abhijit; Mahadevan, Suvrath; Roy, Arpita; Dixit, Vaibhav; Richardson, Eric Harvey; Dongre, Varun; Pathan, F. M.; Chaturvedi, Priyanka; Shah, Vishal; Ubale, Girish P.; Anandarao, B. G.

In: Publications of the Astronomical Society of the Pacific, Vol. 126, No. 936, 01.02.2014, p. 133-147.

Research output: Contribution to journalArticle

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T1 - The PRL stabilized high-resolution echelle fiber-fed spectrograph

T2 - Instrument description and first radial velocity results

AU - Chakraborty, Abhijit

AU - Mahadevan, Suvrath

AU - Roy, Arpita

AU - Dixit, Vaibhav

AU - Richardson, Eric Harvey

AU - Dongre, Varun

AU - Pathan, F. M.

AU - Chaturvedi, Priyanka

AU - Shah, Vishal

AU - Ubale, Girish P.

AU - Anandarao, B. G.

PY - 2014/2/1

Y1 - 2014/2/1

N2 - We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mount Abu 1.2 m telescope in India. Data obtained as part of the postcommissioning tests with PARAS show velocity precision better than 2 m s-1 over a period of several months on bright RV standard stars. For observations of σ Dra, we report 1.7 m s-1 precision for a period of 7 months, and for HD 9407, we report 2.1 m s-1 over a period of 2 months. PARAS is capable of single-shot spectral coverage of 3800-9500 Å at a resolution of ~67,000. The RV results were obtained between 3800 and 6900 Å using simultaneous wavelength calibration with a thorium-argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01-0.02° C (rms) at 25.55° C and is enclosed in a vacuum vessel at pressure of 0.1 ± 0.03 mbar. The blaze peak efficiency of the spectrograph between 5000 and 6500 Å, including the detector, is ~30%; it is ~25% with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81% reflectivity) is ~7% in the same wavelength region on a clear night with good seeing conditions. The stable point-spread function (PSF), environmental control, existence of a simultaneous calibration fiber, and availability of observing time make PARAS attractive for a variety of exoplanetary and stellar astrophysics projects. Future plans include testing of octagonal fibers for further scrambling of light and extensive calibration over the entire wavelength range up to 9500 Å using thorium-neon (ThNe) or uranium-neon (UNe) spectral lamps. Thus, we demonstrate how such highly stabilized instruments, even on small aperture telescopes, can contribute significantly to the ongoing radial velocity searches for low-mass planets around bright stars.

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