Astrophysics Source Code Library

Making codes discoverable since 1999

Searching for codes credited to 'Lloyd, James P.'

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[ascl:1011.018] chrom_exact: Transit of a Spherical Planet of a Stellar Chromosphere which is Geometrically Thin

Transit light curves for stellar continua have only one minimum and a "U" shape. By contrast, transit curves for optically thin chromospheric emission lines can have a "W" shape because of stellar limb-brightening. We calculate light curves for an optically thin shell of emission and fit these models to time-resolved observations of Si IV absorption by the planet HD209458b. We find that the best fit Si IV absorption model has R_p,SIV/R_*= 0.34+0.07-0.12, similar to the Roche lobe of the planet. While the large radius is only at the limit of statistical significance, we develop formulae applicable to transits of all optically thin chromospheric emission lines.

[ascl:2201.007] tellrv: Radial velocities for low-resolution NIR spectra

tellrv measures absolute radial velocities for low-resolution NIR spectra. It uses telluric features to provide absolute wavelength calibration, and then cross-correlates with a standard star. Observations of a standard star are included for convenience; the code also requires both the telluric and non-telluric-corrected spectra.