Sunday, May 19, 2013

1305.3176 (E. Oliva et al.)

A GIANO-TNG high resolution IR spectrum of the airglow emission    [PDF]

E. Oliva, L. Origlia, R. Maiolino, C. Baffa, V. Biliotti, P. Bruno, G. Falcini, V. Gavriousev, F. Ghinassi, E. Giani, M. Gonzalez, F. Leone, M. Lodi, F. Massi, P. Montegriffo, I. Mochi, M. Pedani, E. Rossetti, S. Scuderi, M. Sozzi, A. Tozzi, E. Valenti
A flux-calibrated high resolution spectrum of the airglow emission is a practical lambda-calibration reference for astronomical spectral observations. It is also useful for constraining the molecular parameters of the OH molecule and the physical conditions in the upper mesosphere. methods: We use the data collected during the first technical commissioning of the GIANO spectrograph at the Telescopio Nazionale Galileo (TNG). The high resolution (R~50,000) spectrum simultaneously covers the 0.95-2.4 micron wavelength range. Relative flux calibration is achieved by the simultaneous observation of spectrophotometric standard star. results: We derive a list of improved positions and intensities of OH infrared lines. The list includes Lambda-split doublets many of which are spectrally resolved. Compared to previous works, the new results correct errors in the wavelengths of the Q-branch transitions. The relative fluxes of OH lines from different vibrational bands show remarkable deviations from theoretical predictions: the Deltav=3,4 lines are a factor of 2 and 4 brighter than expected. We also find evidence of a significant fraction (1-4%) of OH molecules with ``non-thermal'' population of high-J levels. Finally we list wavelengths and fluxes of 153 lines not attributable to OH. Most of these can be associated to O2, while 37 lines in the H band are not identified. The O2 and unidentified lines in the H band account for ~5% of the total airglow flux in this band.
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