Optical, ultraviolet, and infrared observations of isolated neutron stars

Optical--to--X-ray emission in low-absorption AGN: Results from the Swift-BAT 9 month catalogue

Optical-uv spectrum and proper motion of the middle-aged pulsar b1055-52

Orbital and Spin Phase-Resolved Spectroscopy of the Intermediate Polar EX Hya Using XMM-Newton Data

Orbital Decay and Evidence of Disk Formation in the X-ray Binary Pulsar OAO 1657-415

Orbital modulation of X-ray emission lines in Cygnus X-3

Orbital variation of the X-ray emission from the double neutron star binary J1537+1155

Orbital X-ray modulation study of three Supergiant HMXBs

Orders of Fermi- and Plasma-Accelerations of Cosmic Rays

Origin of $10^{15}-10^{16}$G Magnetic Fields in the Central Engine of Gamma Ray Bursts

Origin of Cosmic Rays

Origin of power-law X-ray emission in the Steep power-law state of X-ray Binaries

Origin of TeV Galactic Cosmic Rays

Origin of the bright prompt optical emission in the naked eye burst

Origin of the Cosmic Ray Spectral Hardening

Origin of the Fermi Bubble

Origin of the GeV Emission During the X-ray Flaring Activity in GRB 100728A

Origin of the Ultrahigh-Energy Cosmic Rays and their Spectral Break

Origin of the X-rays and Possible GeV-TeV Emission from the Western Hot Spot Of Pictor A

Origin of Ultrahigh Energy Galactic Cosmic Rays: The Isotropy Problem