Towards 10 cm/s radial velocity accuracy on the Sun using a Fourier transform spectrometer
arXiv:2311.05520 · doi:10.1117/1.JATIS.9.4.045003
Abstract
The IAG solar observatory is producing high-fidelity, ultra-high-resolution spectra (R>500000) of the spatially resolved surface of the Sun using a Fourier Transform spectrometer (FTS). The radial velocity (RV) calibration of these spectra is currently performed using absorption lines from Earth's atmosphere, limiting the precision and accuracy. To improve the frequency calibration precision and accuracy we plan to use a Fabry-Perot etalon (FP) setup that is an evolution of the CARMENES FP design and an iodine cell in combination. To create an accurate wavelength solution, the iodine cell is measured in parallel with the FP. The FP can then be used to transfer the accurate wavelength solution provided by the iodine via simultaneous calibration of solar observations. To verify the stability and precision of the FTS we perform parallel measurements of the FP and an iodine cell. The measurements show an intrinsic stability of the FTS of a level of 1 m/s over 90 hours. The difference between the FP RVs and the iodine cell RVs show no significant trends during the same time span. The RMS of the RV difference between FP and iodine cell is 10.7 cm/s, which can be largely attributed to the intrinsic RV precisions of the iodine cell and the FP (10.2 cm/s and 1.0 cm/s, respectively). This shows that we can calibrate the FTS to a level of 10 cm/s, competitive with current state-of-the-art precision RV instruments. Based on these results we argue that the spectrum of iodine can be used as an absolute reference to reach an RV accuracy of 10 cm/s.
arXiv comment13 pages, 9 figures, to be published in Journal of Astronomical Telescopes, Instruments, and Systems (JATIS)
References in corpus (18)
- ESPRESSO@VLT -- On-sky performance and first results
- Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
- The Sun as a planet-host star: Proxies from SDO images for HARPS radial-velocity variations
- Using the Sun to estimate Earth-like planets detection capabilities.I. Impact of cold spots
- HARPS-N observes the Sun as a star
- The IAG solar flux atlas: Accurate wavelengths and absolute convective blueshift in standard solar spectra
- A comprehensive radial velocity error budget for next generation Doppler spectrometers
- PEPSI deep spectra. I. The Sun-as-a-star
- Reconstructing the solar integrated radial velocity using MDI/SOHO
- Performance Verification of the EXtreme PREcision Spectrograph
- Observing the Sun as a star: Design and early results from the NEID solar feed
- Convective blueshifts in the solar atmosphere, I. Absolute measurements with LARS of the spectral lines at 6302 Å
- The IAG spectral atlas of the spatially resolved Sun: Centre-to-limb observations
- A systematic approach to determining the properties of an iodine absorption cell for high-precision radial velocity measurements
- Fiber-coupling of Fourier Transform Spectrographs
- Observing the integrated and spatially resolved Sun with ultra-high spectral resolution
- Absolute frequency measurement of molecular iodine hyperfine transitions at 647 nm
- Quantifying broadband chromatic drifts in Fabry-Perot resonators for exoplanet science