arXiv subjects

B. E. Corey

Publications and source records attributed to B. E. Corey.

40 records · Page 3Linked to original sources

arXiv2003

A Survey for Transient Astronomical Radio Emission at 611 MHz

We have constructed and operated the Survey for Transient Astronomical Radio Emission (STARE) to detect transient astronomical radio emission at 611 MHz originating from the sky over the northeastern United States. The system is sensitive to transient events on timescales of 0.125 s to a few minutes, with a typical zenith flux density detection threshold of approximately 27 kJy. During 18 months of around-the-clock observing with three geographically separated instruments, we detected a total of 4,318,486 radio bursts. 99.9% of these events were rejected as locally generated interference, determined by requiring the simultaneous observation of an event at all three sites for it to be identified as having an astronomical origin. The remaining 3,898 events have been found to be associated with 99 solar radio bursts. These results demonstrate the remarkably effective RFI rejection achieved by a coincidence technique using precision timing (such as GPS clocks) at geographically separated sites. The non-detection of extra-solar bursting or flaring radio sources has improved the flux density sensitivity and timescale sensitivity limits set by several similar experiments in the 1970s. We discuss the consequences of these limits for the immediate solar neighborhood and the discovery of previously unknown classes of sources. We also discuss other possible uses for the large collection of 611 MHz monitoring data assembled by STARE.

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arXiv1997

The STARE Project: A Progress Report

The Survey for Transient Astronomical Radio Emission (STARE) is a wide-field monitor for transient radio emission at 611 MHz on timescales of fractions of a second to minutes. Consisting of multiple geographically separated total-power radiometers which measure the sky power every 0.125 sec, STARE has been in operation since March 1996. In its first seventeen months of operation, STARE collected data before, during, and after 173 gamma-ray bursts. Seven candidate astronomical radio bursts were detected within +/-1hr of a GRB, consistent with the rate of chance coincidences expected from the local radio interference rates. The STARE data are therefore consistent with an absence of radio counterparts appearing within +/-1hr of GRBs, with 5sigma detection limits ranging from tens to hundreds of kJy. The strengths of STARE relative to other radio counterpart detection efforts are its large solid-angle and temporal coverage. These result in a large number of GRBs occuring in the STARE field of view, allowing studies that are statistical in nature. Such a broad approach may also be valuable if the GRBs are due to a heterogenous set of sources.

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arXiv1996

A 23 GHz Survey of GRB Error Boxes

The Haystack 37-meter telescope was used in a pilot project in May 1995 to observe GRB error boxes at 23~GHz. Seven BATSE error boxes and two IPN arcs were scanned by driving the beam of the telescope rapidly across their area. For the BATSE error boxes, the radio observations took place two to eighteen days after the BATSE detection, and several boxes were observed more than once. Total power data were recorded continuously as the telescope was driven at a rate of 0.2~degrees/second, yielding Nyquist sampling of the beam with an integration time of 50~milliseconds, corresponding to a theoretical rms sensitivity of 0.5~Jy. Under conditions of good weather, this sensitivity was achieved. In a preliminary analysis of the data we detect only two sources, 3C273 and 0552+398, both catalogued sources that are known to be variable at 23~GHz. Neither had a flux density that was unusally high or low at the time of our observations.

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arXiv1995

VLBI Observations of the Gravitational Lens System 0957+561

We present hybrid maps of the A and B images of 0957+561 from each of four sessions of 6 cm VLBI observations that span the six-year interval 1987-1993. The inner- and outer-jets are clearly detected, and confirm the structures reported previously. There is no evidence of change in the separation between the core and inner-jet components, so the prospect of measuring the time delay using differential proper motions is not promising. The flux density in the core of each image peaked between 1989 and 1992. From the variation in these flux densities, we obtain a time-delay estimate of $\sim$1 yr.

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