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Optical tracking of deep-space spacecraft in Halo L2 orbits and beyond: The Gaia mission as a pilot case
Buzzoni, Alberto; Altavilla, Giuseppe; Galleti, Silvia
We tackle the problem of accurate optical tracking of distant man-made probes, on Halo orbit around the Earth-Sun libration point L2 and beyond, along interplanetary transfers. The improved performance of on-target tracking, especially when observing with small-class telescopes is assessed providing a general estimate of the expected S/N ratio in …
A journey through scales
Retinò, Alessandro
Direct satellite observations of energy transfer between large and small space plasma scales contribute to our understanding of how matter in the Universe gets hot.
Neutral Hydrogen and Its Emission Lines in the Solar Corona
Vial, Jean-Claude; Chane-Yook, Martine
Since the Lyman-α rocket observations of Gabriel (Solar Phys.21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coron…
Detection of coronal mass ejections using AdaBoost on grayscale statistic features
Guo, Juan; Zhang, Ling; Yin, Jian-qin +2 more
We present an automatic algorithm to detect coronal mass ejections (CMEs) in Large Angle Spectrometric Coronagraph (LASCO) C2 running difference images. The algorithm includes 3 steps: (1) split the running difference images into blocks according to slice size and analyze the grayscale statistics of the blocks from a set of images with and without…
Stellar subsystems of the galaxy NGC 1313
Tikhonov, N. A.; Galazutdinova, O. A.
Based on archival Hubble Space Telescope (HST) ACS/WFC images, we have performed stellar photometry for eight fields of the spiral galaxy NGC 1313 and its satellite, the low-mass Sph/Irr galaxy AM0319-662. Stars of various ages have been identified on the constructed Hertzsprung-Russell diagrams: young supergiants, middle-aged stars, and old stars…
O VI 1032 Å intensity and Doppler shift oscillations above a coronal hole: Magnetosonic waves or quasi-periodic upflows?
Raymond, J. C.; Mancuso, S.; Taricco, C. +1 more
On 1996 December 19, the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO) conducted a special high-cadence sit-and-stare observation in the O vi 1032 Å spectral line above a polar coronal hole at a heliocentric distance of 1.38 R⊙. The ~ 9-h dataset was analyzed by applying advanced spec…
Connecting VLBI and Gaia celestial reference frames
Malkin, Zinovy
The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the mutual orientation and rotation between the optical Gaia Celestial Reference Frame (GCRF) and the 3rd generation …
SEDEBLEND: a new method for deblending spectral energy distributions in confused imaging
Scott, Douglas; Swinbank, Mark; MacKenzie, Todd P.
For high-redshift submillimetre or millimetre sources detected with single-dish telescopes, interferometric follow-up has shown that many are multiple submillimetre galaxies blended together. Confusion-limited Herschel observations of such targets are also available, and these sample the peak of their spectral energy distribution (SED) in the far-…
Undercover EUV Solar Jets Observed by the Interface Region Imaging Spectrograph
Innes, D. E.; Chen, N. -H.
It is well-known that extreme ultraviolet (EUV) emission emitted at the solar surface is absorbed by overlying cool plasma. Especially in active regions, dark lanes in EUV images suggest that much of the surface activity is obscured. Simultaneous observations from the Interface Region Imaging Spectrograph, consisting of UV spectra and slit-jaw ima…
Angular Dependence of the Facular-Sunspot Coverage Relation as Derived by MDI Magnetograms
Criscuoli, S.
Previous studies have shown that the variation over the solar magnetic activity cycle of the area of facular/network features identified from broad-band and narrow-band imagery is positively correlated with the sunspot area and number, the relation being described as either linear or quadratic. On the other hand, the temporal variation of the spat…