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XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources

The 18806 ROSAT All Sky Survey Bright Source Catalog (RASS/BSC) X-ray sources are quantitatively cross-associated with near-infrared (NIR) sources from the Two Micron All Sky Survey Point Source Catalog (2MASS/PSC). An association catalog is presented, listing the most likely counterpart for each RASS/BSC source, the probability Pid that the NIR source and X-ray source are uniquely associated, and the probability Pnoid that none of the 2MASS/PSC sources are associated with the X-ray source. The catalog includes 3853 high quality (Pid>0.98) X-ray--NIR matches, 2280 medium quality (0.98>Pid>0.9) matches, and 4153 low quality (0.9>Pid>0.5) matches. Of the high quality matches, 1418 are associations that are not listed in the SIMBAD database, and for which no high quality match with a USNO-A2 optical source was presented for the RASS/BSC source in previous work. The present work offers a significant number of new associations with RASS/BSC objects that will require optical/NIR spectroscopy for classification. For example, of the 6133 Pid>0.9 2MASS/PSC counterparts presented in the association catalog, 2411 have no classification listed in the SIMBAD database. These 2MASS/PSC sources will likely include scientifically useful examples of known source classes of X-ray emitters (white dwarfs, coronally active stars, active galactic nuclei), but may also contain previously unknown source classes. It is determined that all coronally active stars in the RASS/BSC should have a counterpart in the 2MASS/PSC, and that the unique association of these RASS/BSC sources with their NIR counterparts thus is confusion limited.Comment: 14 pages, 13 figures, 5 table

A millimeter-wave slot-V antenna

A V-shaped slot antenna built on a dielectric substrate is presented. The antenna is a nonresonant, traveling-wave design, with a predicted impedance in the range from 50 Ω to 80 Ω. Calculations indicate that this antenna should have a gain of 15 dB with 3 dB beamwidths of 10° in the H plane and 64° in the E plane. Pattern measurements at 90 GHz support the theory. It should be possible to equalize the two beamwidths with a cylindrical lens. The broad bandwidth and high gain characteristics make the slot- V a good candidate for picosecond optoelectronic measurements. Fabrication is simple, and it should be possible to make this antenna at wavelengths as short as 10 μm with conventional photolithography

An LDMOS VHF class-E power amplifier using a high-Q novel variable inductor

In this paper, an lateral diffused metal-oxide-semiconductor-based very high-frequency class-E power amplifier has been investigated theoretically and experimentally. Simulations were verified by amplifier measurements and a record-high class-E output power was obtained at 144 MHz, which is in excellent agreement with simulations. The key of the results is the use of efficient device models, simulation tools, and the invention of a novel high-Q inductor for the output series resonance network. The latter allows for low losses in the output network and, simultaneously, a wide tuning range for maximum output power or maximum efficiency optimization

The Astronomer's Telegram: A Web-based Short-Notice Publication System for the Professional Astronomical Community

The Astronomer's Telegram (ATEL; http://fire.berkeley.edu:8080/) is a web based short-notice (<4000 characters) publication system for reporting and commenting on new astronomical observations, offering for the first time in astronomy effectively instantaneous distribution of time-critical information for the entire professional community. It is designed to take advantage of the World Wide Web's simple user interface and the ability of computer programs to provide nearly all the necessary functions. One may post a Telegram, which is instantly (<1 second) available at the Web-site, and distributed by email within 24 hours through the Daily Email Digest, which is tailored to the subject selections of each reader. Optionally, urgent Telegrams may be distributed through Instant Email Notices. While ATEL will be of particular use to observers of transient objects (such as gamma-ray bursts, microlenses, supernovae, novae, or X-ray transients) or in fields which are rapidly evolving observationally, there are no restrictions on subject matter.Comment: 4 pages, LaTeX, requires aaspp4.st

Statistical Re-examination of Reported Emission Lines in the X-ray Afterglow of GRB 011211

(abridged) A 0.2-12 keV spectrum obtained with the XMM EPIC/pn instrument of GRB 011211 was found by Reeves et al. (2002) to contain emission lines which were interpreted to be from Mg XI, Si XIV, S XVI, Ar XVIII, and Ca XX, at a lower redshift (z_{obs}=1.88) than the host galaxy (z_{host}=2.14). We examine the spectrum independently, and find that the claimed lines would not be discovered in a blind search. Specifically, Monte Carlo simulations show that they would be observed in 10% of featureless spectra with the same signal-to-noise. Imposing a model in which the two brightest lines would be Si XIV and S XVI K-alpha emission possibly velocity shifted to between z=1.88--2.40, such features would be found in between ~1.2-2.6% of observed featureless spectra. We find the detection significances to be insufficient to justify the claim of detection and the model put forth to explain them. K-alpha line complexes are also found at z=1.2 and z=2.75 of significance equal to or greater than that at z=1.88. If one adopts the z=1.88 complex as significant, one must also adopt the other two complexes to be significant. The interpretation of these data in the context of the model proposed by Reeves et al. is therefore degenerate, and cannot be resolved by these data alone.Comment: 23 pages, 4 figures. MNRAS, accepted. Expanded discussio