SearchCal: a virtual observatory tool for searching calibrators in optical long baseline interferometry

Abstract

Context. In long baseline interferometry, the raw fringe contrast must be calibrated to obtain the true visibility and then those observables that can be interpreted in terms of astrophysical parameters. The selection of suitable calibration stars is crucial for obtaining the ultimate precision of interferometric instruments like the VLTI. Potential calibrators must have spectro-photometric properties and a sky location close to those of the scientific target. Aims. We have developed software (SearchCal) that builds an evolutive catalog of stars suitable as calibrators within any given user-defined angular distance and magnitude around the scientific target. We present the first version of SearchCal dedicated to the bright-object case (V ≤ 10; K ≤ 5). Methods. Star catalogs available at the CDS are consulted via web requests. They provide all the useful information for selecting of calibrators. Missing photometries are computed with an accuracy of 0.1 mag and the missing angular diameters are calculated with a precision better than 10%. For each star the squared visibility is computed by taking the wavelength and the maximum baseline of the foreseen observation into account. Results. SearchCal is integrated into ASPRO, the interferometric observing preparation software developed by the JMMC, available at the address: http://mariotti.fr.

Detection of solar-like oscillations in the bright red giant starsγPiscium andθ1 Tauri from a 190-day high-precision spectroscopic multi-site campaign

“…Wittkowski et al 2004, for a more detailed discussion about this assumption). The derived value (listed in Table 6) agrees perfectly with the diameter provided by the JMMC's SearchCal tool (Bonneau et al 2006). The final calibrated squared visibilities and closure phases are graphically depicted in Fig.…”

Kinematics and geometrical study of the Be stars 48 Persei andψPersei with the VEGA/CHARA interferometer

“…For each channel, we measured the product V(λ1) × V(λ2) and φdiff(λ2). The same processing is done for the calibrators HD 18411 & HD 12303, whose angular diameters θ LD (0.41 ± 0.03 mas, m v = 4.677 mag for HD 18411 and 0.26 ± 0.02 mas, m v = 4.992 mag for HD 12303) were estimated using the SearchCal software (Bonneau et al 2006) from the Jean-Marie Mariotti Center 1 . The visibilities in the Hα line were measured using pass bands of δλ = 2.4 nm for ψ Per and δλ = 1.75 nm for 48 Per, which cover the width of these lines in each case (see Fig.…”

A high angular and spectral resolution view into the hidden companion ofεAurigae

“…After studying the list of calibrators used for the PTI and the CHARA/MIRC observations, we use the B3V star HD 32630 (V = 3. m 16) as the calibrator star for our observations. Different estimates of its angular diameter could be found in the literature or through the usual web tools such as getCal or Searchcal; see Bonneau et al (2006) for the bright, and Bonneau et al (2011b) for the faint calibrator cases 2 . It appears that the estimates range from 0.34 ± 0.02 mas for SearchCal to 0.6 ± 0.2 mas for getCal.…”