Search Publications
Source Region of the Decameter-Hectometric Type II Radio Burst: Shock-Streamer Interaction Region
Wang, Yuming; Wang, Shui; Shen, Chenglong +2 more
D-H type II radio bursts are widely thought to be caused by coronal mass ejections (CMEs). However, it is still unclear where the exact source of the type IIs on the shock surface is. We identify the source regions of the decameter-hectometric (D-H) type IIs based on imaging observations from SOHO/LASCO and the radio dynamic spectrum from Wind/Wav…
Co-registration of laser altimeter tracks with digital terrain models and applications in planetary science
Oberst, J.; Gläser, P.; Haase, I. +1 more
We have derived algorithms and techniques to precisely co-register laser altimeter profiles with gridded Digital Terrain Models (DTMs), typically derived from stereo images. The algorithm consists of an initial grid search followed by a least-squares matching and yields the translation parameters at sub-pixel level needed to align the DTM and the …
The lack of star formation gradients in galaxy groups up to z ∼ 1.6
Finoguenov, A.; Berta, S.; Magnelli, B. +28 more
In the local Universe, galaxy properties show a strong dependence on environment. In cluster cores, early-type galaxies dominate, whereas star-forming galaxies are more and more common in the outskirts. At higher redshifts and in somewhat less dense environments (e.g. galaxy groups), the situation is less clear. One open issue is that of whether a…
Illuminating the Darkest Gamma-Ray Bursts with Radio Observations
Menten, K. M.; Greiner, J.; Berger, E. +21 more
We present X-ray, optical, near-infrared (IR), and radio observations of gamma-ray bursts (GRBs) 110709B and 111215A, as well as optical and near-IR observations of their host galaxies. The combination of X-ray detections and deep optical/near-IR limits establish both bursts as "dark." Sub-arcsecond positions enabled by radio detections lead to ro…
On the Redshift of the Very High Energy Blazar 3C 66A
Furniss, A.; Williams, D. A.; Prochaska, J. X. +2 more
As a bright gamma-ray source, 3C 66A is of great interest to the high-energy astrophysics community, having a potential for placing cosmological constraints on models for the extragalactic background light (EBL) and the processes which contribute to this photon field. No firm spectroscopic redshift measurement has been possible for this blazar due…
Improving the performance of solar flare prediction using active longitudes information
Huang, X.; Zhang, L.; Wang, H. +1 more
Context. Solar flare prediction models normally depend on properties of active regions, such as sunspot area, McIntosh classifications, Mount Wilson classifications, and various measures of the magnetic field. Nevertheless, the positional information of active regions has not been used.
Aims: We define a metric, DARAL (distance bet…
Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations
Covino, S.; Pian, E.; Sbarufatti, B. +21 more
We report on multiwavelength observations of the blazar PKS 0537-441 (z = 0.896) obtained from microwaves through γ-rays by Submillimeter Array, Rapid Eye Mounting, Automatic Telescope for Optical Monitoring (ATOM), Swift and Fermi mostly during 2008 August-2010 April. Strong variability has been observed in γ-rays, with two major flaring episodes…
Inclusion of Real-Time In-Situ Measurements into the UCSD Time-Dependent Tomography and Its Use as a Forecast Algorithm
Jackson, B. V.; Buffington, A.; Hick, P. P. +3 more
The University of California, San Diego (UCSD) three-dimensional (3D) time-dependent tomography program, used for over a decade to reconstruct and forecast coronal mass ejections (CMEs), does so from observations of interplanetary scintillation (IPS) taken using the Solar-Terrestrial Environment Laboratory (STELab) radio arrays in Japan. An earlie…
The velocity field of sunspot penumbrae. II. Return flow and magnetic fields of opposite polarity
Franz, M.; Schlichenmaier, R.
Aims: We search for penumbral magnetic fields of opposite polarity and for their correspondence with downflows.
Methods: We used spectropolarimetric HINODE data of a spot very close to disk center to suppress the horizontal velocity components as much as possible. We focus our study on 3-lobe Stokes V profiles.
Results: From forward…
The density and temperature structure near the exobase of Saturn from Cassini UVIS solar occultations
Sandel, B. R.; Yelle, R. V.; Koskinen, T. T. +4 more
We analyzed 15 solar occultations observed by the Cassini UVIS instrument to constrain the density and temperature structure near the exobase of Saturn. We retrieved the density of H2 and thus the temperature at altitudes higher than 1900 km above the 1 bar level by analyzing the ionization continuum of H2 at wavelengths shor…