CalFUSE v3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer

Since its launch in 1999, the Far Ultraviolet Spectroscopic Explorer (FUSE) has made over 4600 observations of some 2500 individual targets. The data are reduced by the Principal Investigator team at the Johns Hopkins University and archived at the Multimission Archive at Space Telescope (MAST). The data-reduction software package, called CalFUSE, has evolved considerably over the lifetime of the mission. The entire FUSE data set has recently been reprocessed with CalFUSE v3.2, the latest version of this software. This paper describes CalFUSE v3.2, the instrument calibrations upon which it is based, and the format of the resulting calibrated data files.Comment: To appear in PASP; 29 pages, 13 figures, uses aastex, emulateap

Tiny-Scale Molecular Structures in the Magellanic Clouds (Part 1)

We report on the {\small FUSE} detections of the HD and CO molecules {\bf on the lines of sight towards three Large Magellanic stars}: Sk $-$67D05, Sk $-$68D135, and Sk $-$69D246. HD is also detected for the first time {\bf on the lines of sight towards two Small Magellanic Cloud stars}: AV 95 and Sk 159. While the HD and CO abundances are expected to be lower in the Large Magellanic Cloud where molecular fractions are a third of the Galactic value and where the photodissociation flux is up to thousands times larger, we report an average HD/H$_2$ ratio of 1.4$\pm$0.5 ppm and CO/H$_2$ ratio ranging from 0.8 to 2.7 ppm similar to the Galactic ones. We tentatively identify a deuterium reservoir (hereafter D--reservoir) towards the Small Magellanic Cloud, along the light path to AV 95. We derive a D/H ratio ranging from 1. 10$^{-6}$ to 1.1 10$^{-5}$.Comment: 34 pages, 10 tables, 12 figures, accepted for publication in A&

On measuring planetary winds using high-resolution spectroscopy in visible wavelengths

We present a new method that uses high-resolution spectroscopy in the visible wavelength domain to measure planetary winds. A rotating atmosphere illuminated by the Sun induces a Doppler shift in the back-scattered solar light. Its analysis with a cross-dispersed echelle spectrometer allows the direct determination of both the wind speed and direction. We describe in this paper the image and data processing algorithms used in the method and implemented in a data reduction and analysis package. Since the velocity of planetary winds leads to Doppler shifts smaller than the width of the solar lines, accurate Doppler measurements are performed by running the algorithm proposed by [CITE], which is an optimum technique using the full available spectral information. We apply the method to Io as a test case, a small slowly-rotating body with no atmosphere, to measure its solid rotation. The observations span wavelengths from 414 to 621 nm and were carried out with the Ultraviolet and Visual Echelle Spectrograph (UVES) on the 8.2 m Kueyen unit at the Very Large Telescope (VLT – ESO). The results we obtain for Io validate the principle of the method by optimally measuring the well-known surface rotational velocity of this moon, with an uncertainty smaller than 2 m s-1. However, the analysis of the set of observations shows that systematic errors are large and one needs to consider the retrieved velocity as a lower limit

Characterization of zonal winds in the stratosphere of Titan with UVES

Titan has been observed with UVES, the UV–Visual Echelle Spectrograph at the Very Large Telescope, with the aim of characterizing the zonal wind flow. We use a retrieval scheme originally developed for absolute stellar accelerometry [Connes, P., 1985. Astrophys. Space Sci., 110, 211–255] to extract the velocity signal by simultaneously taking into account all the lines present in the spectrum. The method allows to measure the Doppler shift induced at a given point by the zonal wind flow, with high precision. The short-wavelength channel (4200–5200 Å) probes one scale height higher than the long-wavelength one (5200–6200 Å), and we observe statistically significant evidence for stronger winds at higher altitudes. The results show a high dispersion. Globally, we detect prograde zonal winds, with lower limits of 62 and 50 m s-1 at the regions centered at 200 and 170 km altitude, but approximately a quarter of the measurements indicates null or retrograde winds

Characterization of zonal winds in the stratosphere of Titan with UVES: 2. Observations coordinated with the Huygens Probe entry

International audienceThe Huygens Probe has successfully entered Titan's atmosphere and landed on its surface on 14 January 2005. With the aim of characterizing the zonal wind flow in Titan's stratosphere close to the time of entry, coordinated observations were carried out at the Very Large Telescope on the nights of 7, 12, 14, and 15 January. As in our previous investigation (Luz et al., 2005), we used the UVES instrument, mounted on the Kueyen-UT2 telescope, simultaneously achieving high spectral resolving power and high spatial resolution. The field has been derotated in order to align the 0.3-arcsec aperture perpendicularly to Titan's rotation axis. In this configuration, spatial information in the east-west direction is preserved in a set of spectra in the direction perpendicular to dispersion. We present measurements of zonal winds obtained with the technique of absolute accelerometry. The observations were made in the wavelength range 4200-6200 Å, probing between 115 and 280 km, with peak contributions at 200 and 170 km for the lower and upper parts of the domain. We detect prograde zonal winds with lower limits 46 and 53 ms-1 at these altitudes. These values are close to our previous measurements