Comparing radial velocities of atmospheric lines with radiosonde measurements

Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.52). 10/2011; DOI: 10.1111/j.1365-2966.2011.20015.x
Source: arXiv

ABSTRACT The precision of radial velocity (RV) measurements depends on the precision
attained on the wavelength calibration. One of the available options is using
atmospheric lines as a natural, freely available wavelength reference. Figueira
et al. (2010) measured the RV of O2 lines using HARPS and showed that the
scatter was only of ~10 m/s over a timescale of 6 yr. Using a simple but
physically motivated empirical model, they demonstrated a precision of 2 m/s,
roughly twice the average photon noise contribution. In this paper we take
advantage of a unique opportunity to confirm the sensitivity of the telluric
absorption lines RV to different atmospheric and observing conditions: by means
of contemporaneous in-situ wind measurements by radiosondes.
The RV model fitting yielded similar results to that of Figueira et al.
(2010), with lower wind magnitude values and varied wind direction. The probes
confirmed the average low wind magnitude and suggested that the average wind
direction is a function of time as well. The two approaches deliver the same
results in what concerns wind magnitude and agree on wind direction when
fitting is done in segments of a couple of hours. Statistical tests show that
the model provides a good description of the data on all timescales, being
always preferable to not fitting any atmospheric variation. The smaller the
timescale on which the fitting can be performed (down to a couple of hours),
the better the description of the real physical parameters. We conclude then
that the two methods deliver compatible results, down to better than 5 m/s and
less than twice the estimated photon noise contribution on O2 lines RV
measurement. However, we cannot rule out that parameters alpha and gamma
(dependence on airmass and zero-point, respectively) have a dependence on time
or exhibit some cross-talk with other parameters (abridged).

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the status of the 2004 edition of the HITRAN molecular spectroscopic database. The HITRAN compilation consists of several components that serve as input for radiative transfer calculation codes: individual line parameters for the microwave through visible spectra of molecules in the gas phase; absorption cross-sections for molecules having dense spectral features, i.e., spectra in which the individual lines are unresolvable; individual line parameters and absorption cross-sections for bands in the ultra-violet; refractive indices of aerosols; tables and files of general properties associated with the database; and database management software. The line-by-line portion of the database contains spectroscopic parameters for 39 molecules including many of their isotopologues.The format of the section of the database on individual line parameters of HITRAN has undergone the most extensive enhancement in almost two decades. It now lists the Einstein A-coefficients, statistical weights of the upper and lower levels of the transitions, a better system for the representation of quantum identifications, and enhanced referencing and uncertainty codes. In addition, there is a provision for making corrections to the broadening of line transitions due to line mixing.
    Journal of Quantitative Spectroscopy and Radiative Transfer 12/2005; · 2.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Precise near-infrared radial velocimetry enables efficient detection and transit verification of low-mass extrasolar planets orbiting M dwarf hosts, which are faint for visible-wavelength radial velocity surveys. The TripleSpec Exoplanet Discovery Instrument, or TEDI, is the combination of a variable-delay Michelson interferometer and a medium-resolution (R=2700) near-infrared spectrograph on the Palomar 200" Hale Telescope. We used TEDI to monitor GJ 699, a nearby mid-M dwarf, over 11 nights spread across 3 months. Analysis of 106 independent observations reveals a root-mean-square precision of less than 37 m/s for 5 minutes of integration time. This performance is within a factor of 2 of our expected photon-limited precision. We further decompose the residuals into a 33 m/s white noise component, and a 15 m/s systematic noise component, which we identify as likely due to contamination by telluric absorption lines. With further development this technique holds promise for broad implementation on medium-resolution near-infrared spectrographs to search for low-mass exoplanets orbiting M dwarfs, and to verify low-mass transit candidates.
    Publications of the Astronomical Society of the Pacific 02/2011; 123. · 3.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pan-STARRS is a highly cost-effective, modular and scalable approach to wide-field optical/NIR imaging. It uses 1.8m telescopes with very large (7 square degree) field of view and revolutionary1.4 billion pixel CCD cameras with low noise and rapid read-out to provide broad-band imaging from 400-1000nm wavelength. The first single telescope system, PS1, has been deployed on Haleakala on Maui, and has been collecting science quality survey data for approximately six months. PS1 will be joined by a second telescope PS2 in approximately 18 months. A four aperture system is planned to become operational following the end of the PS1 mission. This will be able to scan the entire visible sky to approximately 24th magnitude in less than a week, thereby meeting the goals set out by the NAS 2000 decadal review for a "Large Synoptic Sky Telescope". Here we review the technical design, and give an update on the progress that has been made with the PS1 system.
    Proc SPIE 07/2010;

Full-text (2 Sources)

Available from
May 27, 2014