We present intensive optical, infrared, and radio monitoring observations of the BL Lac object OJ 287, taken between the years 1993-1998. Two large optical outbursts were detected at the predicted times in November 1994 and December 1995. The detection of these outbursts supports the binary black hole model for OJ 287. Optical and radio

We simulate the characteristics of the Galactic population of radio and gamma-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed with supernova-kick velocities in the Galactic disk and randomly dispersed in age back to 109 years. They are evolved in the Galactic gravitational potential to the present time

The soft X-ray transient (SXT) XTE J1859+226 has been optically monitored from Tenerife using the IAC-80 and OGS 1m telescopes since its outburst on 1999 Oct 10 (see IAUC 7274, 7279). This R-band CCD photometry revealed a smooth decline of 0.017 mag/day for most of the next 8 months in parallel with that seen by the RXTE ASM, until two large ( ~2.5

We present the discovery by optical and near-infrared imaging of an extremely red, low-luminosity population of isolated objects in the young, nearby stellar cluster around the multiple, massive star σ Orionis. The proximity (352 parsecs), youth (1 million to 5 million years), and low internal extinction make this cluster an ideal site to explore

Chandra observations of two quiecent black-hole x-ray nova (BHXN), A0620-00 and GS2000+25 emphasize the reality of the difference in the x-ray luminosity swings of these systems and their neutron-star containing analogs. For A0620-00, the slope of the x-ray spectrum is much more accurately determined than had previously been possible, and is

The Chandra Multiwavelength Plane (ChaMPlane) Survey is a project to identify a large sample of serendipitous X-ray sources in the galactic plane, including cataclysmic variables, quiescent low mass X-ray binaries (qLMXBs: in both black hole and neutron star systems), Be X-ray binaries and stellar coronal sources (see Grindlay et al 2000, BAAS, 196