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We report on a search for engineered signals from a sample of 692 nearby stars using the Robert C. Byrd Green Bank Telescope, undertaken as part of the Breakthrough Listen Initiative search for extraterrestrial intelligence. Observations were made over 1.1-1.9 GHz (L band), with three sets of five-minute observations of the 692 primary targets, interspersed with five-minute observations of secondary targets. By comparing the "ON" and "OFF" observations, we are able to identify terrestrial interference and place limits on the presence of engineered signals from putative extraterrestrial civilizations inhabiting the environs of the target stars. During the analysis, 11 events passed our thresholding algorithm, but a detailed analysis of their properties indicates that they are consistent with known examples of anthropogenic radio-frequency interference. We conclude that, at the time of our observations, none of the observed systems host high-duty-cycle radio transmitters emitting between 1.1 and 1.9 GHz with an Equivalent Isotropic Radiated Power of ∼10 13 W, which is readily achievable by our own civilization. Our results suggest that fewer than ∼0.1% of the stellar systems within 50 pc possess the type of transmitters searched in this survey.

We report the first detections of the repeating fast radio burst source FRB 121102 above 5.2 GHz. Observations were performed using the 4−8 GHz receiver of the Robert C. Byrd Green Bank Telescope with the Breakthrough Listen digital backend. We present the spectral, temporal and polarization properties of 21 bursts detected within the first 60 minutes of a total 6-hour observations. These observations comprise the highest burst density yet reported in the literature, with 18 bursts being detected in the first 30 minutes. A few bursts clearly show temporal sub-structures with distinct spectral properties.These sub-structures superimpose to provide enhanced peak signal-to-noise ratio at higher trial dispersion measures. Broad features occur in ∼ 1 GHz wide subbands that typically differ in peak frequency between bursts within the band.Finer-scale structures (∼ 10 − 50 MHz) within these bursts are consistent with that expected from Galactic diffractive interstellar scintillation. The bursts exhibit nearly 100% linear polarization, and a large average rotation measure of 9.359±0.012 × 10 4 rad m −2 (in the observer's frame). No circular polarization was found for any burst. We measure an approximately constant polarization position angle in the 13 brightest bursts. The peak flux densities of the reported bursts have average values (0.2±0.1 Jy), similar to those seen at lower frequencies (< 3 GHz), while the average burst widths (0.64±0.46 ms) are relatively narrower.Subject headings:

The Spitzer Deep, Wide-Field Survey (SDWFS) is a four-epoch infrared survey of 10 deg 2 in the Boötes field of the NOAO Deep Wide-Field Survey using the IRAC instrument on the Spitzer Space Telescope. SDWFS, a Spitzer Cycle 4 Legacy project, occupies a unique position in the area-depth survey space defined by other Spitzer surveys. The four epochs that make up SDWFS permit-for the first time-the selection of infrared-variable and high proper motion objects over a wide field on timescales of years. Because of its large survey volume, SDWFS is sensitive to galaxies out to z ∼ 3 with relatively little impact from cosmic variance for all but the richest systems. The SDWFS data sets will thus be especially useful for characterizing galaxy evolution beyond z ∼ 1.5. This paper explains the SDWFS observing strategy and data processing, presents the SDWFS mosaics and source catalogs, and discusses some early scientific findings. The publicly released, full-depth catalogs contain 6.78, 5.23, 1.20, and 0.96 × 10 5 distinct sources detected to the average 5σ , 4 -diameter, aperture-corrected limits of 19.77, 18.83, 16.50, and 15.82 Vega mag at 3.6, 4.5, 5.8, and 8.0 μm, respectively. The SDWFS number counts and color-color distribution are consistent with other, earlier Spitzer surveys. At the 6 minute integration time of the SDWFS IRAC imaging, > 50% of isolated Faint Images of the Radio Sky at Twenty cm radio sources and > 80% of on-axis XBoötes sources are detected out to 8.0 μm. Finally, we present the four highest proper motion IRAC-selected sources identified from the multi-epoch imaging, two of which are likely field brown dwarfs of mid-T spectral class.