The Sunrise balloon-borne solar observatory consists of a 1 m aperture Gregory telescope, a UV filter imager, an imaging vector polarimeter, an image stabilization system, and further infrastructure. The first science flight of Sunrise yielded high-quality data that revealed the structure, dynamics, and evolution of solar convection, oscillations, and magnetic fields at a resolution of around 100 km in the quiet Sun. After a brief description of instruments and data, the first qualitative results are presented. In contrast to earlier observations, we clearly see granulation at 214 nm. Images in Ca ii H display narrow, short-lived dark intergranular lanes between the bright edges of granules. The very small-scale, mixed-polarity internetwork fields are found to be highly dynamic. A significant increase in detectable magnetic flux is found after phase-diversity-related reconstruction of polarization maps, indicating that the polarities are mixed right down to the spatial resolution limit and probably beyond.

Abstract. The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 10 6 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2cmpx~1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma.OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 67P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250-1000 nm at an angular resolution of 18.6 /xradpx -1 . The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 ¡xrad px~1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countries.

We characterize the observational properties of the convectively driven vortex flows recently discovered on the quiet Sun, using magnetograms, Dopplergrams and images obtained with the 1-m balloon-borne Sunrise telescope . By visual inspection of time series, we find some 3.1 × 10 −3 vortices Mm −2 min −1 , which is a factor of ∼1.7 larger than previous estimates. The mean duration of the individual events turns out to be 7.9 min, with a standard deviation of 3.2 min. In addition, we find several events appearing at the same locations along the duration of the time series (31.6 min). Such recurrent vortices show up in the proper motion flow field map averaged over the time series. The typical vertical vorticities are 6×10 −3 sec −1 , which corresponds to a period of rotation of some 35 min. The vortices show a preferred counterclockwise sense of rotation, which we conjecture may have to do with the preferred vorticity impinged by the solar differential rotation.

Abstract. The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument was built to determine whether and to what extent small-scale structures in global trace gas distributions and in dynamics are present in the middle atmosphere. To achieve this, trace gases were measured in the middle infrared by the limb scan technique at the highest possible horizontal and vertical resolution. CRISTA uses three telescopes (i.e., three view directions) simultaneously, and has three grating spectrometers for the middle IR (4-14/xm) and one spectrometer for the far IR (15-71 /xm). The optics and detectors are cooled to cryogenic temperatures by supercritical helium or subcooled helium, respectively, in a double cryostat. An instrument overview is given, and the design guidelines are sketched. The CRISTA experiment was flown on the space shuttle STS 66 as part of NASA mission ATLAS 3 on November 3-14, 1994. Orbit altitude was 300 km, and inclination was 57 ø. A campaign of ground-based, balloon, and rocket validation and complementary measurements was performed simultaneously. The CRISTA instrument performed flawlessly. A horizontal resolution of 200 km x 650 km was achieved at the equator, with higher horizontal resolution at higher latitudes. A vertical resolution of 2.5 km (or better) was obtained. The middle atmosphere was found to be highly variable at scales of <1000 km in the stratosphere. Three streamers of tropic/ subtropic air extending to higher latitudes are described. Their meridional scale is -<1000 km, while the zonal scale is of the order of 10,000 km and more. The streamers appear to be typical of specific winter conditions and to play a role in meridional transport. At mesospheric heights a strong tidal temperature oscillation was observed which extended well into the lower thermosphere.

We present the first observations of the transverse component of photospheric magnetic field acquired by the imaging magnetograph Sunrise/IMaX. Using an automated detection method, we obtain statistical properties of 4536 features with significant linear polarization signal. We obtain a rate of occurrence of 7 · 10 −4 s −1 arcsec −2 , which is 1 − 2 orders of magnitude larger than values reported by previous studies. We show that these features have no characteristic size or lifetime. They appear preferentially at granule boundaries with most of them being caught in downflow lanes at some point. Only a small percentage are entirely and constantly embedded in upflows (16%) or downflows (8%).

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The first science flight of the balloon-borne Sunrise telescope took place in June 2009 from ESRANGE (near Kiruna/Sweden) to Somerset Island in northern Canada. We describe the scientific aims and mission concept of the project and give an overview and a description of the various hardware components: the 1-m main telescope with its postfocus science instruments (the UV filter imager SuFI and the imaging vector magnetograph IMaX) and support instruments (image stabilizing and light distribution system ISLiD and correlating wavefront sensor CWS), the optomechanical support structure and the instrument mounting concept, the gondola structure and the power, pointing, and telemetry systems, and the general electronics architecture. We also explain the optimization of the structural and thermal design of the complete payload. The preparations for the science flight are described, including AIV and ground calibration of the instruments. The course of events during the science flight is outlined, up to the recovery activities. Finally, the in-flight performance of the instrumentation is discussed.

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the solar corona. To address the above question, we use highresolution line-of-sight magnetic field data from the Imaging Magnetograph eXperiment instrument on the Sunrise balloon-borne observatory and coronal observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory of an emerging active region. We find that the coronal loops are often rooted at the locations with minor small-scale but persistent oppositepolarity magnetic elements very close to the larger dominant polarity. These opposite-polarity smallscale elements continually interact with the dominant polarity underlying the coronal loop through flux cancellation. At these locations we detect small inverse Y-shaped jets in chromospheric Ca ii H images obtained from the Sunrise Filter Imager during the flux cancellation. Our results indicate that magnetic flux cancellation and reconnection at the base of coronal loops due to mixed polarity fields might be a crucial feature for the supply of mass and energy into the corona.